Publications

@article{nokey,

title = {Local Disorder at the Phase Transition Interrupts Ambipolar Charge Carrier Transport in Large Crystal Methylammonium Lead Iodide Thin Films},

author = {A Biewald and N Giesbrecht and T Bein and P Docampo and A Hartschuh and R Ciesielski},

url = {https://doi.org/10.1021/acs.jpcc.0c06240},

doi = {10.1021/acs.jpcc.0c06240},

issn = {1932-7447},

year  = {2020},

date = {2020-08-25},

journal = {The Journal of Physical Chemistry C},

volume = {124},

number = {38},

pages = {20757-20764},

abstract = {The low-temperature transition from a tetragonal to an orthorhombic crystal phase in methylammonium lead iodide (MAPI) is accompanied by drastic changes in the charge carrier mobility around a critical temperature of approximately 164 K. This transition is studied here using photoluminescence (PL) microscopy on large crystal MAPI thin films, which is extremely sensitive to modifications of the charge carrier dynamics and can resolve physical properties on a single-grain level. The key observation is that ambipolar charge carrier diffusion suddenly stops when the temperature falls below the phase transition temperature. From coexisting PL bands and their spatial distribution, it is concluded that the temperature range from just below the phase transition until about 150 K is determined by a mixed phase where small orthorhombic and tetragonal domains coexist. This results in local disorder, which hinders ambipolar charge carrier diffusion.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Efficient ultrafast all-optical modulation in a nonlinear crystalline gallium phosphide nanodisk at the anapole excitation},

author = {G Grinblat and H Zhang and M P Nielsen and L Krivitsky and R Bert\'{e} and Y Li and B Tilmann and E Cort\'{e}s and R F Oulton and A I Kuznetsov and S A Maier},

url = {https://advances.sciencemag.org/content/advances/6/34/eabb3123.full.pdf},

doi = {10.1126/sciadv.abb3123},

year  = {2020},

date = {2020-08-21},

journal = {Science Advances},

volume = {6},

number = {34},

pages = {eabb3123},

abstract = {High\textendashrefractive index nanostructured dielectrics have the ability to locally enhance electromagnetic fields with low losses while presenting high third-order nonlinearities. In this work, we exploit these characteristics to achieve efficient ultrafast all-optical modulation in a crystalline gallium phosphide (GaP) nanoantenna through the optical Kerr effect (OKE) and two-photon absorption (TPA) in the visible/near-infrared range. We show that an individual GaP nanodisk can yield differential reflectivity modulations of up to ~40%, with characteristic modulation times between 14 and 66 fs, when probed at the anapole excitation (AE). Numerical simulations reveal that the AE represents a unique condition where both the OKE and TPA contribute with the same modulation sign, maximizing the response. These findings highly outperform previous reports on sub\textendash100-fs all-optical switching from resonant nanoscale dielectrics, which have demonstrated modulation depths no larger than 0.5%, placing GaP nanoantennas as a promising choice for ultrafast all-optical modulation at the nanometer scale.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Hot Hydrocarbon-Solvent Slot-Die Coating Enables High-Efficiency Organic Solar Cells with Temperature-Dependent Aggregation Behavior},

author = {H Zhao and H B Naveed and B Lin and X Zhou and J Yuan and K Zhou and H Wu and R Guo and M A Scheel and A Chumakov and S V Roth and Z Tang and P M\"{u}ller-Buschbaum and W Ma},

doi = {10.1002/adma.202002302},

issn = {0935-9648},

year  = {2020},

date = {2020-08-18},

urldate = {2020-08-18},

journal = {Adv Mater},

volume = {32},

number = {39},

pages = {e2002302},

abstract = {Organic solar cells (OSCs) have made rapid progress in terms of their development as a sustainable energy source. However, record-breaking devices have not shown compatibility with large-scale production via solution processing in particular due to the use of halogenated environment-threatening solvents. Here, slot-die fabrication with processing involving hydrocarbon-based solvents is used to realize highly efficient and environmentally friendly OSCs. Highly compatible slot-die coating with roll-to-roll processing using halogenated (chlorobenzene (CB)) and hydrocarbon solvents (1,2,4-trimethylbenzene (TMB) and ortho-xylene (o-XY)) is used to fabricate photoactive films. Controlled solution and substrate temperatures enable similar aggregation states in the solution and similar kinetics processes during film formation. The optimized blend film nanostructures for different solvents in the highly efficient PM6:Y6 blend is adopted to show a similar morphology, which results in device efficiencies of 15.2%, 15.4%, and 15.6% for CB, TMB, and o-XY solvents. This approach is successfully extended to other donor-acceptor combinations to demonstrate the excellent universality of this method. The results combine a method to optimize the aggregation state and film formation kinetics with the fabrication of OSCs with environmentally friendly solvents by slot-die coating, which is a critical finding for the future development of OSCs in terms of their scalable production and high-performance.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Atomistic defects as single-photon emitters in atomically thin MoS2},

author = {K Barthelmi and J Klein and A H\"{o}tger and L Sigl and F Sigger and E Mitterreiter and S Rey and S Gyger and M Lorke and M Florian and F Jahnke and T Taniguchi and K Watanabe and V Zwiller and K D J\"{o}ns and U Wurstbauer and C Kastl and A Weber-Bargioni and J J Finley and K M\"{u}ller and A W Holleitner},

url = {https://doi.org/10.1063/5.0018557},

doi = {10.1063/5.0018557},

issn = {0003-6951},

year  = {2020},

date = {2020-08-17},

journal = {Applied Physics Letters},

volume = {117},

number = {7},

pages = {070501},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Near-atomic-scale observation of grain boundaries in a layer-stacked two-dimensional polymer},

author = {H Y Qi and H Sahabudeen and B K Liang and M Polozij and M A Addicoat and T E Gorelik and M Hambsch and M Mundszinger and S Park and B V Lotsch and S C B Mannsfeld and Z K Zheng and R H Dong and T Heine and X L Feng and U Kaiser},

url = {\<Go to ISI\>://WOS:000560465800030},

doi = {10.1126/sciadv.abb5976},

issn = {2375-2548},

year  = {2020},

date = {2020-08-14},

journal = {Science Advances},

volume = {6},

number = {33},

abstract = {Two-dimensional (2D) polymers, hold great promise in the rational materials design tailored for next-generation applications. However, little is known about the grain boundaries in 2D polymers, not to mention their formation mechanisms and potential influences on the material's functionalities. Using aberration-corrected high-resolution transmission electron microscopy, we present a direct observation of the grain boundaries in a layer-stacked 2D polyimine with a resolution of 2.3 angstrom, shedding light on their formation mechanisms. We found that the polyimine growth followed a "birth-and-spread" mechanism. Antiphase boundaries implemented a self-correction to the missing-linker and missing-node defects, and tilt boundaries were formed via grain coalescence. Notably, we identified grain boundary reconstructions featuring closed rings at tilt boundaries. Quantum mechanical calculations revealed that boundary reconstruction is energetically allowed and can be generalized into different 2D polymer systems. We envisage that these results may open up the opportunity for future investigations on defect-property correlations in 2D polymers.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Fast and Anomalous Exciton Diffusion in Two-Dimensional Hybrid Perovskites},

author = {J D Ziegler and J Zipfel and B Meisinger and M Menahem and X Zhu and T Taniguchi and K Watanabe and O Yaffe and D A Egger and A Chernikov},

url = {https://doi.org/10.1021/acs.nanolett.0c02472},

doi = {10.1021/acs.nanolett.0c02472},

issn = {1530-6984},

year  = {2020},

date = {2020-08-10},

journal = {Nano Letters},

volume = {20},

number = {9},

pages = {6674-6681},

abstract = {Two-dimensional hybrid perovskites are currently in the spotlight of condensed matter and nanotechnology research due to their intriguing optoelectronic and vibrational properties with emerging potential for light-harvesting and light-emitting applications. While it is known that these natural quantum wells host tightly bound excitons, the mobilities of these fundamental optical excitations at the heart of the optoelectronic applications are barely explored. Here, we directly monitor the diffusion of excitons through ultrafast emission microscopy from liquid helium to room temperature in hBN-encapsulated two-dimensional hybrid perovskites. We find very fast diffusion with characteristic hallmarks of free exciton propagation for all temperatures above 50 K. In the cryogenic regime, we observe nonlinear, anomalous behavior with an exceptionally rapid expansion of the exciton cloud followed by a very slow and even negative effective diffusion. We discuss our findings in view of efficient exciton\textendashphonon coupling, highlighting two-dimensional hybrids as promising platforms for basic research and optoelectronic applications.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {In Situ Studies of Solvent Additive Effects on the Morphology Development during Printing of Bulk Heterojunction Films for Organic Solar Cells},

author = {D Yang and S Grott and X Jiang and K S Wienhold and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smtd.202000418},

doi = {https://doi.org/10.1002/smtd.202000418},

issn = {2366-9608},

year  = {2020},

date = {2020-08-09},

urldate = {2020-08-09},

journal = {Small Methods},

volume = {4},

number = {9},

pages = {2000418},

abstract = {Abstract The development of polymer morphology and crystallinity of printed bulk heterojunction (BHJ) films doped with the different solvent additives 1,8-diiodooctane (DIO) or diphenyl ether (DPE) is investigated with in situ grazing-incidence small/wide-angle X-ray scattering. The solvent additives, having different boiling points, lead to a different film drying behavior and morphology growth states in the BHJ films of the benzothiadiazole-based polymer (PPDT2FBT) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The phase demixing in the printed films is changing over time along with solvent evaporation. Polymer domains start aggregating to form larger domains in the liquid\textendashliquid phase, while phase separation mainly occurs in the liquid\textendashsolid phase. The present work provides a profound insight into the morphology development of printed BHJ films doped with different solvent additives, which is particularly important for the large-scale fabrication of organic photovoltaics.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Following In Situ the Evolution of Morphology and Optical Properties during Printing of Thin Films for Application in Non-Fullerene Acceptor Based Organic Solar Cells},

author = {K S Wienhold and C L Weindl and S Yin and T Tian and M Schwartzkopf and A Rothkirch and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsami.0c12390},

doi = {10.1021/acsami.0c12390},

issn = {1944-8244},

year  = {2020},

date = {2020-08-07},

urldate = {2020-08-07},

journal = {ACS Applied Materials \& Interfaces},

volume = {12},

number = {36},

pages = {40381-40392},

abstract = {In situ printing gives insight into the evolution of morphology and optical properties during slot-die coating of active layers for application in organic solar cells and enables an upscaling and optimization of the thin film deposition process and the photovoltaic performance. Active layers based on the conjugated polymer donor with benzodithiophene units PBDB-T-2Cl and the non-fullerene small-molecule acceptor IT-4F are printed with a slot-die coating technique and probed in situ with grazing incidence small-angle X-ray scattering, grazing incidence wide-angle X-ray scattering, and ultraviolet/visible light spectroscopy. The formation of the morphology is followed from the liquid state to the final dry film for different printing conditions (at 25 and 35 °C), and five regimes of film formation are determined. The morphological changes are correlated to changing optical properties. During the film formation, crystallization of the non-fullerene small-molecule acceptor takes place and polymer domains with sizes of some tens of nanometers emerge. A red shift of the optical band gap and a broadening of the absorbance spectrum occurs, which allow for exploiting the sun spectrum more efficiently and are expected to have a favorable effect on the solar cell performance.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Toward Standardized Photocatalytic Oxygen Evolution Rates Using RuO2@TiO2 as a Benchmark},

author = {H A Vignolo-Gonz\'{a}lez and S Laha and A Jim\'{e}nez-Solano and T Oshima and V Duppel and P Sch\"{u}tzend\"{u}be and B V Lotsch},

url = {http://www.sciencedirect.com/science/article/pii/S2590238520303799},

doi = {https://doi.org/10.1016/j.matt.2020.07.021},

issn = {2590-2385},

year  = {2020},

date = {2020-08-05},

journal = {Matter},

volume = {3},

number = {2},

pages = {464-486},

abstract = {Summary Quantitative comparison of photocatalytic performances across different photocatalysis setups is technically challenging. Here, we combine the concepts of relative and optimal photonic efficiencies to normalize activities with an internal benchmark material, RuO2 photodeposited on a P25-TiO2 photocatalyst, which was optimized for reproducibility of the oxygen evolution reaction (OER). Additionally, a general set of good practices was identified to ensure reliable quantification of photocatalytic OER, including photoreactor design, photocatalyst dispersion, and control of parasitic reactions caused by the sacrificial electron acceptor. Moreover, a method combining optical modeling and measurements was proposed to quantify the benchmark absorbed and scattered light (7.6% and 81.2%, respectively, of λ = 300\textendash500 nm incident photons), rather than just incident light (≈AM 1.5G), to estimate its internal quantum efficiency (16%). We advocate the adoption of the instrumental and theoretical framework provided here to facilitate material standardization and comparison in the field of artificial photosynthesis.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Investigation of Molecular Dynamics of a PTB7:PCBM Polymer Blend with Quasi-Elastic Neutron Scattering},

author = {D Schwaiger and W Lohstroh and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsapm.0c00455},

doi = {10.1021/acsapm.0c00455},

year  = {2020},

date = {2020-08-03},

urldate = {2020-08-03},

journal = {ACS Applied Polymer Materials},

volume = {2},

number = {9},

pages = {3797-3804},

abstract = {In organic photovoltaics, bulk heterojunctions (BHJs) of organic semiconductor substances such as conjugated polymers and fullerenes are frequently used as active layers in which light is transformed into free charge carriers. The performance of the respective solar cells is critically influenced by the inner morphology of the active layer. Besides structural, also dynamical properties are important but by far less frequently investigated. In this study, we probe the polymer dynamics of an active layer composed of a low band gap polymer and a fullerene derivate. The acceptor [6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM) and the donor poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7), as well as their 1:1 blend, are probed with time-of-flight quasi-elastic neutron scattering. Our observable timescale window of motions covers a range from 1 ps to approximately 50 ps. We probe a temperature range from 150 to 400 K, which covers the reported maximum power conversion efficiency of the respective BHJ solar cells. Within this temperature range, PCBM does not show any dynamics on the observable timescale. Blending with PCBM (wt. ratio 1:1) causes frustration of the PTB7 side-chain dynamics, which manifests in increased relaxation times and decreased diffusion coefficients. Important for solar cell applications, temperature variations do have a major impact on the polymer dynamics, which in some circumstances are far more pronounced than the influence of blending with PCBM. Furthermore, we show that this temperature dependence follows an Arrhenius-type behavior.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Solution-processed p-type nanocrystalline CoO films for inverted mixed perovskite solar cells},

author = {B Li and Y C Rui and J L Xu and Y Q Wang and J X Yang and Q H Zhang and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000533529500009},

doi = {10.1016/j.jcis.2020.03.119},

issn = {0021-9797},

year  = {2020},

date = {2020-08-01},

journal = {Journal of Colloid and Interface Science},

volume = {573},

pages = {78-86},

abstract = {Inorganic p-type materials show great potential as the hole transport layer in perovskite solar cells with the merits of low costs and enhanced chemical stability. As a p-type material, cobalt oxide (CoO) has received so far not that level of attention despite its high hole mobility. Herein, solution-processed p-type CoO nanocrystalline films are developed for inverted mixed perovskite solar cells. The ultrafine CoO nanocrystals are synthesized via an oil phase method, which are subsequently treated by a ligand exchange process using pyridine solvent to remove the long alkyl chains covering the nanocrystals. From this homogeneous colloidal solution CoO films are obtained, which exhibit a smooth and pinhole free surface morphology with high transparency and good conductivity. The ultraviolet photoelectron spectrum also indicates that the energy levels of the CoO film match well with the mixed perovskite Cs-0(.05)(FA(0)(.)(83)MA(0)(.17))(0.95)(I0.83Br0.17)(3). Inverted solar cells based on crystalline Co0 films with ligand exchange show a reasonable energy conversion efficiency, whereas devices based on CoO films without ligand exchange suffer from a strong S-shape JV-characteristic. Thus, the crystalline CoO films are foreseen to pave a new way of inorganic hole transport materials in the fields of perovskite solar cells. (C) 2020 Elsevier Inc. All rights reserved.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Revealing Nanoscale Chemical Heterogeneities in Polycrystalline Mo-BiVO(4)Thin Films},

author = {J Eichhorn and S E Reyes-Lillo and S Roychoudhury and S Sallis and J Weis and D M Larson and J K Cooper and I D Sharp and D Prendergast and F M Toma},

url = {\<Go to ISI\>://WOS:000555446200001},

doi = {10.1002/smll.202001600},

issn = {1613-6810},

year  = {2020},

date = {2020-08-01},

urldate = {2020-08-01},

journal = {Small},

volume = {16},

pages = {2001600},

abstract = {The activity of polycrystalline thin film photoelectrodes is impacted by local variations of the material properties due to the exposure of different crystal facets and the presence of grain/domain boundaries. Here a multi-modal approach is applied to correlate nanoscale heterogeneities in chemical composition and electronic structure with nanoscale morphology in polycrystalline Mo-BiVO4. By using scanning transmission X-ray microscopy, the characteristic structure of polycrystalline film is used to disentangle the different X-ray absorption spectra corresponding to grain centers and grain boundaries. Comparing both spectra reveals phase segregation of V(2)O(5)at grain boundaries of Mo-BiVO(4)thin films, which is further supported by X-ray photoelectron spectroscopy and many-body density functional theory calculations. Theoretical calculations also enable to predict the X-ray absorption spectral fingerprint of polarons in Mo-BiVO4. After photo-electrochemical operation, the degraded Mo-BiVO(4)films show similar grain center and grain boundary spectra indicating V(2)O(5)dissolution in the course of the reaction. Overall, these findings provide valuable insights into the degradation mechanism and the impact of material heterogeneities on the material performance and stability of polycrystalline photoelectrodes.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Regulating Photochemical Selectivity with Temperature: Isobutanol on TiO2(110)},

author = {C Courtois and C A Walenta and M Tschurl and U Heiz and C M Friend},

url = {\<Go to ISI\>://WOS:000557854400021},

doi = {10.1021/jacs.0c04411},

issn = {0002-7863},

year  = {2020},

date = {2020-07-29},

urldate = {2020-07-29},

journal = {Journal of the American Chemical Society},

volume = {142},

number = {30},

pages = {13072-13080},

abstract = {Selective photocatalytic transformations of chemicals derived from biomass, such as isobutanol, have been long envisioned for a sustainable chemical production. A strong temperature dependence in the reaction selectivity is found for isobutanol photo-oxidation on rutile TiO2(110). The strong temperature dependence is attributed to competition between thermal desorption of the primary photoproduct and secondary photochemical steps. The aldehyde, isobutanal, is the primary photoproduct of isobutanol. At room temperature, isobutanal is obtained selectively from photo-oxidation because of rapid thermal desorption. In contrast, secondary photo-oxidation of isobutanal to propane dominates at lower temperature (240 K) due to the persistence of isobutanal on the surface after it is formed. The byproduct of isobutanal photo-oxidation is CO, which is evolved at higher temperature as a consequence of thermal decomposition of an intermediate, such as formate. The photo-oxidation to isobutanal proceeds after thermally induced isobutoxy formation. These results have strong implications for controlling the selectivity of photochemical processes more generally, in that, selectivity is governed by competition of desorption vs secondary photoreaction of products. This competition can be exploited to design photocatalytic processes to favor specific chemical transformations of organic molecules.},

keywords = {Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {All-Dielectric Silicon Nanoslots for Er3+ Photoluminescence Enhancement},

author = {B Kalinic and T Cesca and S Mignuzzi and A Jacassi and I G Balasa and S A Maier and R Sapienza and G Mattei},

url = {\<Go to ISI\>://WOS:000553352700004},

doi = {10.1103/PhysRevApplied.14.014086},

issn = {2331-7019},

year  = {2020},

date = {2020-07-28},

journal = {Physical Review Applied},

volume = {14},

number = {1},

abstract = {We study, both experimentally and theoretically, the modification of Er3+ photoluminescence properties in Si dielectric nanoslots. The ultrathin nanoslot (down to 5-nm thickness), filled with Er in SiO2, boosts the electric and magnetic local density of states via coherent near-field interaction. We report an experimental 20-fold enhancement of the radiative decay rate with negligible losses. Moreover, via modifying the geometry of the all-dielectric nanoslot, the outcoupling of the emitted radiation to the far field can be strongly improved, without affecting the strong decay-rate enhancement given by the nanoslot structure. Indeed, for a periodic square array of slotted nanopillars an almost one-order-of-magnitude-higher Er3+ PL intensity is measured with respect to the unpatterned structures. This has a direct impact on the design of more efficient CMOS-compatible light sources operating at telecom wavelengths.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Quantized many-body spin-valley textures in charge tunable monolayer MoS2},

author = {J Klein and A H\"{o}tger and M Florian and A Steinhoff and A Delhomme and T Taniguchi and K Watanabe and F Jahnke and A W Holleitner and M Potemski},

url = {https://www.researchgate.net/profile/Andreas-Stier/publication/343304456_Quantized_many-body_spin-valley_textures_in_charge_tunable_monolayer_MoS_2/links/5f226a5ca6fdcccc439945ae/Quantized-many-body-spin-valley-textures-in-charge-tunable-monolayer-MoS-2.pdf},

year  = {2020},

date = {2020-07-28},

journal = {arXiv preprint arXiv:2007.14441},

abstract = {We explore the many-body interaction of neutral, positively and negatively charged electron-hole pairs in a MoS2 monolayer with the distinct spin and valley textures of resident charges via density dependent high field magneto-optical spectroscopy. For the neutral exciton we unexpectedly observe nonlinear valley Zeeman effects, which we explain by dipolar spin-interactions of the exciton with the spin and valley polarized Fermi sea. At electron densities below 4·1012cm−2 we observe quantum oscillations in the photoluminescence of the intravalley trion as well as a Landau level occupation dependent non-uniform Zeeman shifts from which we determine both effective electron and hole masses. By increasing the local charge density to a situation where the Fermi energy dominates over the other relevant energy scales in the system, the magneto-optical response becomes dependent on the occupation of the fully spin-polarized Landau levels in both K/K0 valleys producing magnetooptical signatures of a many-body state. Our experiments unequivocally demonstrate that the exciton in monolayer semiconductors is a single particle boson only close to charge neutrality and that it smoothly transitions into a polaronic state with a spin-valley flavour that is defined by the local Landau level quantized spin and valley texture away from charge neutrality.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Unique Behavior of Halide Double Perovskites with Mixed Halogens},

author = {D Han and M Ogura and A Held and H Ebert},

url = {https://doi.org/10.1021/acsami.0c08240},

doi = {10.1021/acsami.0c08240},

issn = {1944-8244},

year  = {2020},

date = {2020-07-23},

urldate = {2020-07-23},

journal = {ACS Applied Materials \& Interfaces},

volume = {12},

number = {33},

pages = {37100-37107},

abstract = {Engineering halide double perovskite (A2M+M3+XVII6) by mixing elements is a viable way to tune its electronic and optical properties. In spite of many emerging experiments on halide double perovskite alloys, the basic electronic properties of the alloys have not been fully understood. In this work, we chose Cs2AgBiCl6 as an example and systematically studied electronic properties of its different site alloys Cs2NaxAg1\textendashxBiCl6, Cs2AgSbxBi1\textendashxCl6, and Cs2AgBi(BrxCl1\textendashx)6 (x = 0.25, 0.5, 0.75) by first-principles calculations. Interestingly, the halogen site alloy shows opposite behavior to M+ and M3+ cation site alloys; that is, Cs2AgBi(BrxCl1\textendashx)6 displays virtual crystal behavior without substantial broadening, while Cs2NaxAg1\textendashxBiCl6 and Cs2AgSbxBi1\textendashxCl6 show split-band behaviors with substantial broadening, which indicates that lifetimes of electrons and holes in Cs2AgBi(BrxCl1\textendashx)6 would be longer than those in Cs2NaxAg1\textendashxBiCl6 and Cs2AgSbxBi1\textendashxCl6. We further found that long lifetimes of electrons and holes are common for mixed halide perovskites. Moreover, the band alignment is provided to determine the band gap change of alloys and to understand the transport of electrons and holes when these pure compounds form heterostructures. Our systematical studies should be helpful for future optoelectronic applications of halide perovskites.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Key Factor Study for Amphiphilic Block Copolymer-Templated Mesoporous SnO(2)Thin Film Synthesis: Influence of Solvent and Catalyst},

author = {S S Yin and T Tian and K S Wienhold and C L Weindl and R J Guo and M Schwartzkopf and S V Roth and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000550676200001},

doi = {10.1002/admi.202001002},

issn = {2196-7350},

year  = {2020},

date = {2020-07-21},

journal = {Advanced Materials Interfaces},

abstract = {As a crucial material in the field of energy storage, SnO(2)thin films are widely applied in daily life and have been in the focus of scientific research. Compared to the planar counterpart, mesoporous SnO(2)thin films with high specific surface area possess more attractive physical and chemical properties. In the present work, a novel amphiphilic block copolymer-assisted sol-gel chemistry is utilized for the synthesis of porous tin oxide (SnO2). Two key factors for the sol-gel stock solution preparation, the solvent category and the catalyst content, are systematically varied to tune the thin film morphologies. A calcination process is performed to remove the polymer template at 500 degrees C in ambient conditions. The surface morphology and the buried inner structure are probed with scanning electron microscope and grazing-incidence small-angle X-ray scattering. Crystallinity is characterized by X-ray diffraction. The multi-dimensional characterization results suggest that cassiterite SnO(2)with spherical, cylindrical, and vesicular pore structures are obtained. The variation of the film morphology is governed by the preferential affinity of the utilized solvent mixture and the hydrogen bond interaction between the employed cycloether and H2O molecules in the solution.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Machine-Learned Charge Transfer Integrals for Multiscale Simulations in Organic Thin Films},

author = {M Rinderle and W Kaiser and A Mattoni and A Gagliardi},

url = {https://doi.org/10.1021/acs.jpcc.0c04355},

doi = {10.1021/acs.jpcc.0c04355},

issn = {1932-7447},

year  = {2020},

date = {2020-07-20},

journal = {The Journal of Physical Chemistry C},

volume = {124},

number = {32},

pages = {17733-17743},

abstract = {Gaining insight into structure\textendashproperty relations is a key factor for the development of organic electronics. We present a multiscale framework for charge carrier mobilities in organic thin films empowered by machine-learned charge transfer integrals. The choice of the molecular representation is crucial for accurate and sensitive predictions. Using pentacene thin films, we investigate kernel based algorithms and systematically compare representations ranging from system-specific geometric to Coulomb matrix features to predict absolute and logarithmic transfer integrals. We use the predicted transfer integrals to compute the mobility, including its anisotropy, and compare it to reference values. Best accuracies were obtained by models using the interaction part of the Coulomb matrix as a feature and the logarithm of the transfer integral as a target. We achieve R2 values of 0.97 for transfer integrals within an extensive range of 20 orders of magnitude and less than 27% error in the mobility. We show the transferability of the CIP feature for tetracene and DNTT with excellent prediction accuracies. Furthermore, we demonstrate that the interaction part of the CM successfully encodes the molecular identity and provides a highly sensitive ML framework. The presented framework opens the possibility for highly accurate mesoscopic transport simulations saving orders of magnitude in computational cost.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Origin of Poisoning in Methanol Photoreforming on TiO2(110): The Importance of Thermal Back-Reaction Steps in Photocatalysis},

author = {C Courtois and M Eder and S L Kollmannsberger and M Tschurl and C A Walenta and U Heiz},

url = {\<Go to ISI\>://WOS:000551549800025},

doi = {10.1021/acscatal.0c01615},

issn = {2155-5435},

year  = {2020},

date = {2020-07-17},

urldate = {2020-07-17},

journal = {Acs Catalysis},

volume = {10},

number = {14},

pages = {7747-7752},

abstract = {Alcohol photoreforming on titania represents a perfect model system for elucidating fundamental processes in the heterogeneous photocatalysis of semiconductors. One important but open question is the origin of poisoning during the photoreaction of primary alcohols on a bare, reduced rutile TiO2(110) crystal under ultrahigh vacuum conditions. By comparing the photocatalytic properties of methanol and 2-methyl-2-pentanol, it is demonstrated that the fading activity in methanol photoreforming does not originate from the often-assigned increase of trap states for photon-generated charge carriers. Instead, we attribute the apparent catalyst poisoning to an increased rate of thermal back reactions, particularly to that of the photochemical oxidation step. While overall back reactions are generally considered in photocatalysis, back reactions of individual steps are largely neglected so far. Our work shows that their inclusion in the reaction scheme is inevitable for the comprehensive modeling of photocatalytic processes.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Rational Design of Covalent Cobaloxime-Covalent Organic Framework Hybrids for Enhanced Photocatalytic Hydrogen Evolution},

author = {K Gottschling and G Savasci and H Vignolo-Gonzalez and S Schmidt and P Mauker and T Banerjee and P Rovo and C Ochsenfeld and B V Lotsch},

url = {\<Go to ISI\>://WOS:000551495700030},

doi = {10.1021/jacs.0c02155},

issn = {0002-7863},

year  = {2020},

date = {2020-07-15},

journal = {Journal of the American Chemical Society},

volume = {142},

number = {28},

pages = {12146-12156},

abstract = {Covalent organic frameworks (COFs) display a unique combination of chemical tunability, structural diversity, high porosity, nanoscale regularity, and thermal stability. Recent efforts are directed at using such frameworks as tunable scaffolds for chemical reactions. In particular, COFs have emerged as viable platforms for mimicking natural photosynthesis. However, there is an indisputable need for efficient, stable, and economical alternatives for the traditional platinum-based cocatalysts for light-driven hydrogen evolution. Here, we present azide-functionalized chloro(pyridine)cobaloxime hydrogen-evolution cocatalysts immobilized on a hydrazone-based COF-42 backbone that show improved and prolonged photocatalytic activity with respect to equivalent physisorbed systems. Advanced solid-state NMR and quantum-chemical methods allow us to elucidate details of the improved photoreactivity and the structural composition of the involved active site. We found that a genuine interaction between the COF backbone and the cobaloxime facilitates recoordination of the cocatalyst during the photoreaction, thereby improving the reactivity and hindering degradation of the catalyst. The excellent stability and prolonged reactivity make the herein reported cobaloxime-tethered COF materials promising hydrogen evolution catalysts for future solar fuel technologies.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Doping Dependent In-Plane and Cross-Plane Thermoelectric Performance of Thin n-Type Polymer P(NDI2OD-T2) Films},

author = {R M Kluge and N Saxena and W Chen and V Korstgens and M Schwartzkopf and Q Zhong and S V Roth and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000535017100001},

doi = {10.1002/adfm.202003092},

issn = {1616-301X},

year  = {2020},

date = {2020-07-09},

urldate = {2020-07-09},

journal = {Advanced Functional Materials},

volume = {30},

number = {28},

abstract = {Thermoelectric generators pose a promising approach in renewable energies as they can convert waste heat into electricity. In order to build high efficiency devices, suitable thermoelectric materials, both n- and p-type, are needed. Here, the n-type high-mobility polymer poly[N,N '-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5 '-(2,2 '-bithiophene) (P(NDI2OD-T2)) is focused upon. Via solution doping with 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-N,N-diphenylaniline (N-DPBI), a maximum power factor of (1.84 +/- 0.13) mu W K-2 m(-1) is achieved in an in-plane geometry for 5 wt% dopant concentration. Additionally, UV-vis spectroscopy and grazing-incidence wide-angle X-ray scattering are applied to elucidate the mechanisms of the doping process and to explain the discrepancy in thermoelectric performance depending on the charge carriers being either transported in-plane or cross-plane. Morphological changes are found such that the crystallites, built-up by extended polymer chains interacting via lamellar and pi-pi stacking, re-arrange from face- to edge-on orientation upon doping. At high doping concentrations, dopant molecules disturb the crystallinity of the polymer, hindering charge transport and leading to a decreased power factor at high dopant concentrations. These observations explain why an intermediate doping concentration of N-DPBI leads to an optimized thermoelectric performance of P(NDI2OD-T2) in an in-plane geometry as compared to the cross-plane case.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Spin Polarization Dynamics of Free Charge Carriers in CsPbI3 Nanocrystals},

author = {S Strohmair and A Dey and Y Tong and L Polavarapu and B J Bohn and J Feldmann},

url = {\<Go to ISI\>://WOS:000548893200004},

doi = {10.1021/acs.nanolett.9b05325},

issn = {1530-6984},

year  = {2020},

date = {2020-07-08},

journal = {Nano Letters},

volume = {20},

number = {7},

pages = {4724-4730},

abstract = {Lead halide perovskites (LHPs) exhibit large spin-orbit coupling (SOC), leading to only twofold-degenerate valence and conduction bands and therefore allowing for efficient optical orientation. This makes them ideal materials to study charge carrier spins. With this study we elucidate the spin dynamics of photoexcited charge carriers and the underlying spin relaxation mechanisms in CsPbI3 nanocrystals by employing time-resolved differential transmission spectroscopy (DTS). We find that the photoinduced spin polarization significantly diminishes during thermalization and cooling toward the energetically favorable band edge. Temperature-dependent DTS reveals a decay in spin polarization that is more than 1 order of magnitude faster at room temperature (3 ps) than at cryogenic temperatures (32 ps). We propose that spin relaxation of free charge carriers in large-SOC materials like LHPs occurs as a result of carrier-phonon scattering, as described by the Elliott-Yafet mechanism.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Total scattering reveals the hidden stacking disorder in a 2D covalent organic framework},

author = {A M P\"{u}tz and M W Terban and S Bette and F Haase and R E Dinnebier and B V Lotsch},

url = {http://dx.doi.org/10.1039/D0SC03048A},

doi = {10.1039/D0SC03048A},

issn = {2041-6520},

year  = {2020},

date = {2020-07-08},

journal = {Chemical Science},

abstract = {Interactions between extended π-systems are often invoked as the main driving force for stacking and crystallization of 2D organic polymers. In covalent organic frameworks (COFs), the stacking strongly influences properties such as the accessibility of functional sites, pore geometry, and surface states, but the exact nature of the interlayer interactions is mostly elusive. The stacking mode is often identified as eclipsed based on observed high symmetry diffraction patterns. However, as pointed out by various studies, the energetics of eclipsed stacking are not favorable and offset stacking is preferred. This work presents lower and higher apparent symmetry modifications of the imine-linked TTI-COF prepared through high- and low-temperature reactions. Through local structure investigation by pair distribution function analysis and simulations of stacking disorder, we observe random local layer offsets in the low temperature modification. We show that while stacking disorder can be easily overlooked due to the apparent crystallographic symmetry of these materials, total scattering methods can help clarify this information and suggest that defective local structures could be much more prevalent in COFs than previously thought. A detailed analysis of the local structure helps to improve the search for and design of highly porous tailor-made materials.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Electronic structure investigation of wide band gap semiconductors\textemdashMg2PN3 and Zn2PN3: experiment and theory},

author = {Al M F Fattah and M R Amin and M Mallmann and S Kasap and W Schnick and A Moewes},

url = {http://dx.doi.org/10.1088/1361-648X/ab8f8a},

doi = {10.1088/1361-648x/ab8f8a},

issn = {0953-8984 

1361-648X},

year  = {2020},

date = {2020-07-06},

journal = {Journal of Physics: Condensed Matter},

volume = {32},

number = {40},

pages = {405504},

abstract = {The research on nitridophosphate materials has gained significant attention in recent years due to the abundance of elements like Mg, Zn, P, and N. We present a detailed study of band gap and electronic structure of M2PN3 (M = Mg, Zn), using synchrotron-based soft x-ray spectroscopy measurements as well as density functional theory (DFT) calculations. The experimental N K-edge x-ray emission spectroscopy (XES) and x-ray absorption spectroscopy (XAS) spectra are used to estimate the band gaps, which are compared with our calculations along with the values available in literature. The band gap, which is essential for electronic device applications, is experimentally determined for the first time to be 5.3 ± 0.2 eV and 4.2 ± 0.2 eV for Mg2PN3 and Zn2PN3, respectively. The experimental band gaps agree well with our calculated band gaps of 5.4 eV for Mg2PN3 and 3.9 eV for Zn2PN3, using the modified Becke\textendashJohnson (mBJ) exchange potential. The states that contribute to the band gap are investigated with the calculated density of states especially with respect to two non-equivalent N sites in the structure. The calculations and the measurements predict that both materials have an indirect band gap. The wide band gap of M2PN3 (M = Mg, Zn) could make it promising for the application in photovoltaic cells, high power RF applications, as well as power electronic devices.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Tailoring the orientation of perovskite crystals via adding two-dimensional polymorphs for perovskite solar cells},

author = {R Guo and A Buyruk and X Jiang and W Chen and L K Reb and M A Scheel and T Ameri and P M\"{u}ller-Buschbaum},

url = {http://dx.doi.org/10.1088/2515-7655/ab90d0},

doi = {10.1088/2515-7655/ab90d0},

issn = {2515-7655},

year  = {2020},

date = {2020-07-03},

urldate = {2020-07-03},

journal = {Journal of Physics: Energy},

volume = {2},

number = {3},

pages = {034005},

abstract = {Organic-inorganic perovskite materials are attracting increasing attention for their use in high-performance solar cells due to their outstanding properties, such as long diffusion lengths, low recombination rate, and tunable bandgap. Finding an effective method of defect passivation is thought to be a promising route for improvements toward narrowing the distribution of the power conversion efficiency (PCE) values, given by the spread in the PCE over different devices fabricated under identical conditions, for easier commercialization. In this work, we add 2‐(4‐fluoroph-enyl)ethyl ammonium iodide (p-f-PEAI) into the bulk of a mixed cation lead halide perovskite (CH3NH3PbBr3)0.15(HC(NH2)2PbI3)0.85 thin film. We investigate the influence of different p-f-PEAI concentrations on the optical properties, morphology, crystal orientation, charge carrier dynamics, and device performance. We observe that introducing the proper amount of p-f-PEAI changes the preferential orientation of the perovskite crystals, promotes the strength of the crystal textures, and suppresses non-radiative charge recombination. Thus, we obtain a narrower distribution of the PCE of perovskite solar cells (PSCs) without sacrificing the PCE values reached. This is an important step toward better reproducibility to realize the commercialization of PSCs.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Locally-triggered hydrophobic collapse induces global interface self-cleaning in van-der-Waals heterostructures at room-temperature},

author = {S Wakolbinger and F R Geisenhof and F Winterer and S Palmer and J G Crimmann and K Watanabe and T Taniguchi and F Trixler and R T Weitz},

url = {\<Go to ISI\>://WOS:000528571100001},

doi = {10.1088/2053-1583/ab7bfc},

issn = {2053-1583},

year  = {2020},

date = {2020-07-03},

urldate = {2020-07-03},

journal = {2d Materials},

volume = {7},

number = {3},

abstract = {Mutual relative orientation and well defined, uncontaminated interfaces are the key to obtain van-der-Waals heterostacks with defined properties. Even though the van-der-Waals forces are known to promote the 'self-cleaning' of interfaces, residue from the stamping process, which is often found to be trapped between the heterostructure constituents, can interrupt the interlayer interaction and therefore the coupling. Established interfacial cleaning methods usually involve high-temperature steps, which are in turn known to lead to uncontrolled rotations of layers within fragile heterostructures. Here, we present an alternative method feasible at room temperature. Using the tip of an atomic force microscope (AFM), we locally control the activation of interlayer attractive forces, resulting in the global removal of contaminants from the interface (i.e. the contaminants are also removed in regions several mu m away from the line touched by the AFM tip). By testing combinations of various hydrophobic van-der-Waals materials, mild temperature treatments, and by observing the temporal evolution of the contaminant removal process, we identify that the AFM tip triggers a dewetting-induced hydrophobic collapse and the van-der-Waals interaction is driving the cleaning process. We anticipate that this process is at the heart of the known 'self-cleaning' mechanism. Our technique can be utilized to controllably establish interlayer close coupling between a stack of van-der-Waals layers, and additionally allows to pattern and manipulate heterostructures locally for example to confine material into nanoscopic pockets between two van-der-Waals materials.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {In Operando GISAXS and GIWAXS Stability Study of Organic Solar Cells Based on PffBT4T-2OD:PC71BM with and without Solvent Additive},

author = {D Yang and F C Lohrer and V Korstgens and A Schreiber and B Cao and S Bernstorff and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000544597000001},

doi = {10.1002/advs.202001117},

year  = {2020},

date = {2020-07-01},

urldate = {2020-07-01},

journal = {Advanced Science},

abstract = {Solvent additives are known to modify the morphology of bulk heterojunction active layers to achieve high efficiency organic solar cells. However, the knowledge about the influence of solvent additives on the morphology degradation is limited. Hence, in operando grazing-incidence small and wide angle X-ray scattering (GISAXS and GIWAXS) measurements are applied on a series of PffBT4T-2OD:PC71BM-based solar cells prepared without and with solvent additives. The solar cells fabricated without a solvent additive, with 1,8-diiodoctane (DIO), and witho-chlorobenzaldehyde (CBA) additive show differences in the device degradation and changes in the morphology and crystallinity of the active layers. The mesoscale morphology changes are correlated with the decay of the short-circuit currentJ(sc)and the evolution of crystalline grain sizes is codependent with the decay of open-circuit voltageV(oc). Without additive, the loss inJ(sc)dominates the degradation, whereas with solvent additive (DIO and CBA) the loss inV(oc)rules the degradation. CBA addition increases the overall device stability as compared to DIO or absence of additive.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {In Situ Printing: Insights into the Morphology Formation and Optical Property Evolution of Slot-Die-Coated Active Layers Containing Low Bandgap Polymer Donor and Nonfullerene Small Molecule Acceptor},

author = {K S Wienhold and V Korstgens and S Grott and X Y Jiang and M Schwartzkopf and S V Roth and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000527841700001},

doi = {10.1002/solr.202000086},

issn = {2367-198X},

year  = {2020},

date = {2020-07-01},

journal = {Solar Rrl},

volume = {4},

number = {7},

abstract = {Printing of active layers for high-efficiency organic solar cells with the slot-die coating technique can overcome the challenge of upscaling, which will be needed for organic photovoltaics on its way to marketability. The morphology of a bulk-heterojunction organic solar cell has a very high impact on its power conversion efficiency. Therefore, it is of particular importance to understand the mechanisms of structure formation during printing of active layers to enable further optimization of the solar cell performance and upscaling of the production process. Meniscus-guided slot-die coating of the blend of a low bandgap conjugated polymer donor with benzodithiophene units PBDB-T-SF and the nonfullerene small molecule acceptor IT-4F is studied in situ with optical microscopy, Ultraviolet-visible spectroscopy, and grazing incidence small angle X-ray scattering. The structure formation is followed from the liquid to the final dry film state. Thereby, five regimes of morphology formation are determined. The morphological evolution in the printed active layer is correlated to changing optical properties of the thin film. In the final dry film, polymer domains of several tens of nanometers are observed, which will be favorable for application in high-efficiency organic solar cells.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Discrete interactions between a few interlayer excitons trapped at a MoSe 2\textendashWSe 2 heterointerface},

author = {M Kremser and M Brotons-Gisbert and J Kn\"{o}rzer and J G\"{u}ckelhorn and M Meyer and M Barbone and A V Stier and B D Gerardot and K M\"{u}ller and J J Finley},

issn = {2397-7132},

year  = {2020},

date = {2020-06-24},

journal = {npj 2D Materials and Applications},

volume = {4},

number = {1},

pages = {1-6},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Chiral Assembly of Gold-Silver Core-Shell Plasmonic Nanorods on DNA Origami with Strong Optical Activity},

author = {L Nguyen and M Dass and M F Ober and L V Besteiro and Z M M Wang and B Nickel and A O Govorov and T Liedl and A Heuer-Jungemann},

url = {\<Go to ISI\>://WOS:000543744100103},

doi = {10.1021/acsnano.0c03127},

issn = {1936-0851},

year  = {2020},

date = {2020-06-23},

journal = {Acs Nano},

volume = {14},

number = {6},

pages = {7454-7461},

abstract = {The spatial organization of metal nanoparticles has become an important tool for manipulating light in nanophotonic applications. Silver nanoparticles, particularly silver nanorods, have excellent plasmonic properties but are prone to oxidation and are therefore inherently unstable in aqueous solutions and salt-containing buffers. Consequently, gold nanoparticles have often been favored, despite their inferior optical performance. Bimetallic, i.e., gold-silver core-shell nanoparticles, can resolve this issue. We present a method for synthesizing highly stable gold-silver core-shell NRs that are instantaneously functionalized with DNA, enabling chiral self-assembly on DNA origami. The silver shell gives rise to an enhancement of plasmonic properties, reflected here in strongly increased circular dichroism, as compared to pristine gold nanorods. Gold-silver nanorods are ideal candidates for plasmonic sensing with increased sensitivity as needed in pathogen RNA or antibody testing for nonlinear optics and light-funneling applications in surface enhanced Raman spectroscopy. Furthermore, the control of interparticle orientation enables the study of plasmonic phenomena, in particular, synergistic effects arising from plasmonic coupling of such bimetallic systems.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Genetic-Algorithm-Aided Meta-Atom Multiplication for Improved Absorption and Coloration in Nanophotonics},

author = {C X Liu and S A Maier and G X Li},

url = {\<Go to ISI\>://WOS:000551497000018},

doi = {10.1021/acsphotonics.0c00266},

issn = {2330-4022},

year  = {2020},

date = {2020-06-15},

journal = {Acs Photonics},

volume = {7},

number = {7},

pages = {1716-1722},

abstract = {For a repertoire of nanophotonic systems, including photonic crystals, metasurfaces, and plasmonic structures, unit cell with a single element is conventionally used for the simplicity of design. The extension of the unit cell with multiple meta-atoms drastically enlarges the parameter space and consequently provides potential configurations with improved device performance. Simultaneously, the multiplication does not induce additional complexity for lithography-based fabrications. However, the substantially increased number of parameters makes the design methodology based on physical intuition and parameter sweep impractical. Here, we show that expanding the number of meta-atoms in the unit cell significantly improves the performance of nanophotonic systems by the virtue of a genetic algorithm-based optimizer. Our approach includes physical intuition endowed in the geometry of meta-atoms, providing additional physical understanding of the optimization process. We demonstrate two photonic applications, including prominent enhancement of a broadband absorption and enlargement of the color coverage of plasmonic nanostructures. Not limited to the two proof-of-concept demonstrations, this methodology can be applied to all meta-atom-based nanophotonic systems, including plasmonic near-field enhancement and nonlinear frequency conversion, as well as a simultaneous control of phase and polarization for metasurfaces.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Thickness-Dependence of Exciton-Exciton Annihilation in Halide Perovskite Nanoplatelets},

author = {M Gramlich and B J Bohn and Y Tong and L Polavarapu and J Feldmann and A S Urban},

url = {\<Go to ISI\>://WOS:000547468400064},

doi = {10.1021/acs.jpclett.0c01291},

issn = {1948-7185},

year  = {2020},

date = {2020-06-14},

journal = {Journal of Physical Chemistry Letters},

volume = {11},

number = {13},

pages = {5361-5366},

abstract = {Exciton-exciton annihilation (EEA) and Auger recombination are detrimental processes occurring in semiconductor optoelectronic devices at high carrier densities. Despite constituting one of the main obstacles for realizing lasing in semiconductor nanocrystals (NCs), the dependencies on NC size are not fully understood, especially for those with both weakly and strongly confined dimensions. Here, we use differential transmission spectroscopy to investigate the dependence of EEA on the physical dimensions of thickness-controlled 2D halide perovskite nanoplatelets (NPIs). We find the EEA lifetimes to be extremely short on the order of 7-60 ps. Moreover, they are strongly determined by the NP1 thickness with a power law dependence according to tau(2) proportional to d(5.3). Additional measurements show that the EEA lifetimes also increase for NPIs with larger lateral dimensions. dimensions is critical for deciphering the fundamental laws governing These results show that a precise control of the physical the process especially in 1D and 2D NCs.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Balancing the pre-aggregation and crystallization kinetics enables high efficiency slot-die coated organic solar cells with reduced non-radiative recombination losses},

author = {B Lin and X Zhou and H Zhao and J Yuan and K Zhou and K Chen and H Wu and R Guo and M A Scheel and A Chumakov and S V Roth and Y Mao and L Wang and Z Tang and P M\"{u}ller-Buschbaum and W Ma},

url = {http://dx.doi.org/10.1039/D0EE00774A},

doi = {10.1039/D0EE00774A},

issn = {1754-5692},

year  = {2020},

date = {2020-06-12},

journal = {Energy \& Environmental Science},

volume = {13},

number = {8},

pages = {2467-2479},

abstract = {Slot-die coating being compatible with the roll-to-roll technique has been regarded as a promising tool for upscaling the manufacturing of organic solar cells (OSCs). However, there has been a significant gap between the efficiencies of the state-of-the-art spin-coated devices and the scalable processed devices. The active layer morphology is crucial to achieve high efficiency in OSCs, which depends on the conditions of film fabrication. To figure out and optimize the slot-die coating process, a deeper understanding of the film formation kinetics is important. Herein, in situ measurements of the slot-die coating process based on the PM7:IT4F system are demonstrated to illustrate the aggregation and crystallization evolution at various die temperatures and substrate temperatures. OSCs with a high power conversion efficiency of 13.2% are achieved at 60 °C die temperature/60 °C substrate temperature due to the improved exciton dissociation, charge transport and suppressed non-radiative charge recombination. The optimized morphology is attributed to the balanced polymer pre-aggregation and small molecule crystallization kinetics. The unsuitable die temperature leads to overlarge phase separation and consequently inefficient exciton dissociation while the improper substrate temperature results in weak crystallization and the following shrunken carrier lifetime with strong non-radiative combination. This work provides fundamental understanding on the correlations among processing methodology, solution pre-aggregation, morphology formation kinetics, device physics and device performance and affords guidance for device optimization in scalable manufacturing.},

keywords = {Foundry Organic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Near-Field Spectroscopy of Cylindrical Phonon-Polariton Antennas},

author = {A Mancini and C R Gubbin and R Bert\'{e} and F Martini and A Politi and E Cort\'{e}s and Y Li and S De Liberato and S A Maier},

url = {https://doi.org/10.1021/acsnano.0c02784},

doi = {10.1021/acsnano.0c02784},

issn = {1936-0851},

year  = {2020},

date = {2020-06-12},

urldate = {2020-06-12},

journal = {ACS Nano},

volume = {14},

number = {7},

pages = {8508-8517},

abstract = {Surface phonon polaritons (SPhPs) are hybrid light\textendashmatter states in which light strongly couples to lattice vibrations inside the Reststrahlen band of polar dielectrics at mid-infrared frequencies. Antennas supporting localized surface phonon polaritons (LSPhPs) easily outperform their plasmonic counterparts operating in the visible or near-infrared in terms of field enhancement and confinement thanks to the inherently slower phonon\textendashphonon scattering processes governing SPhP decay. In particular, LSPhP antennas have attracted considerable interest for thermal management at the nanoscale, where the emission strongly diverts from the usual far-field blackbody radiation due to the presence of evanescent waves at the surface. However, far-field measurements cannot shed light on the behavior of antennas in the near-field region. To overcome this limitation, we employ scattering-scanning near-field optical microscopy (sSNOM) to unveil the spectral near-field response of 3C-SiC antenna arrays. We present a detailed description of the behavior of the antenna resonances by comparing far-field and near-field spectra and demonstrate the existence of a mode with no net dipole moment, absent in the far-field spectra, but of importance for applications that exploit the heightened electromagnetic near fields. Furthermore, we investigate the perturbation in the antenna response induced by the presence of the AFM tip, which can be further extended toward situations where for example strong IR emitters couple to LSPhP modes.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Atomistic Positioning of Defects in Helium Ion Treated Single-Layer MoS2},

author = {E Mitterreiter and B Schuler and K A Cochrane and U Wurstbauer and A Weber-Bargioni and C Kastl and A W Holleitner},

url = {\<Go to ISI\>://WOS:000541691200049},

doi = {10.1021/acs.nanolett.0c01222},

issn = {1530-6984},

year  = {2020},

date = {2020-06-10},

journal = {Nano Letters},

volume = {20},

number = {6},

pages = {4437-4444},

abstract = {Structuring materials with atomic precision is the ultimate goal of nanotechnology and is becoming increasingly relevant as an enabling technology for quantum electronics/spintronics and quantum photonics. Here, we create atomic defects in monolayer MoS2 by helium ion (He-ion) beam lithography with a spatial fidelity approaching the single-atom limit in all three dimensions. Using low-temperature scanning tunneling microscopy (STM), we confirm the formation of individual point defects in MoS2 upon He-ion bombardment and show that defects are generated within 9 nm of the incident helium ions. Atom-specific sputtering yields are determined by analyzing the type and occurrence of defects observed in high-resolution STM images and compared with with Monte Carlo simulations. Both theory and experiment indicate that the He-ion bombardment predominantly generates sulfur vacancies.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Real-Time Impedance Analysis for the On-Road Monitoring of Automotive Fuel Cells},

author = {T Lochner and M Perchthaler and J T Binder and J P Sabawa and T A Dao and A S Bandarenka},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/celc.202000510},

doi = {https://doi.org/10.1002/celc.202000510},

issn = {2196-0216},

year  = {2020},

date = {2020-06-09},

journal = {ChemElectroChem},

volume = {7},

number = {13},

pages = {2784-2791},

abstract = {Abstract The on-road monitoring of polymer electrolyte membrane fuel cells (PEMFCs) in automotive systems optimizes their efficiency and fuel consumption in addition to increasing their lifetime. In this work, electrochemical impedance spectroscopy (EIS) measurements and special EIS data analysis algorithms were used to quickly identify fuel cell operational modes and failures during cell operation. The approach developed enables the measurement and analysis time of only a few seconds and allows the accurate extraction of information about the membrane and charge transfer resistance. The data analysis procedures show similar accuracy to that of the complex non-linear least square fitting algorithms. As a result, typical operational failures like air and hydrogen starvation were able to be easily distinguished, and different operational states (membrane humidification, air stoichiometry) of the PEMFCs could be identified.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Temperature Effects in Polymer Electrolyte Membrane Fuel Cells},

author = {T Lochner and R M Kluge and J Fichtner and H A El-Sayed and B Garlyyev and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000546625300001},

doi = {10.1002/celc.202000588},

issn = {2196-0216},

year  = {2020},

date = {2020-06-05},

journal = {Chemelectrochem},

abstract = {The behavior of proton exchange membrane fuel cells (PEMFCs) strongly depends on the operational temperatures. In mobile applications, for instance in fuel cell electric vehicles, PEMFC stacks are often subjected to temperatures as low as -20 degrees C, especially during cold start periods, and to temperatures up to 120 degrees C during regular operation. Therefore, it is important to understand the impact of temperature on the performance and degradation of hydrogen fuel cells to ensure a stable system operation. To get a comprehensive understanding of the temperature effects in PEMFCs, this manuscript addresses and summarizesin- situandex- situinvestigations of fuel cells operated at different temperatures. Initially, different measurement techniques for thermal monitoring are presented. Afterwards, the temperature effects related to the degradation and performance of main membrane electrode assembly components, namely gas diffusion layers, proton exchange membranes and catalyst layers, are analyzed.},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Self-Healing Dyes\textemdashKeeping the Promise?},

author = {M Isselstein and L Zhang and V Glembockyte and O Brix and G Cosa and P Tinnefeld and T Cordes},

url = {https://doi.org/10.1021/acs.jpclett.9b03833},

doi = {10.1021/acs.jpclett.9b03833},

year  = {2020},

date = {2020-06-04},

journal = {The Journal of Physical Chemistry Letters},

volume = {11},

number = {11},

pages = {4462-4480},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Important components for accurate hyperfine coupling constants: electron correlation, dynamic contributions, and solvation effects},

author = {S Vogler and J C B Dietschreit and L D M Peters and C Ochsenfeld},

url = {\<Go to ISI\>://WOS:000543577500001},

doi = {10.1080/00268976.2020.1772515},

issn = {0026-8976},

year  = {2020},

date = {2020-06-03},

journal = {Molecular Physics},

abstract = {The calculation of hyperfine coupling constants is a challenging task in balancing accuracy and computational effort. While previous work has shown the importance of electron correlation and molecular dynamic contributions, we present a systematic study simultaneously analyzing the influence of both effects on hyperfine coupling constants. To this end, we thoroughly study two organic radicals, namely the dimethylamino radical and ethanal radical cation, proving the need to account for conformational flexibility as well as the large influence of electron correlation. Based on these results, we analyse the effect of electron correlation and dynamic simulations on a set of 12 organic radicals, illustrating that both effects are vital for an accuratein silicodescription on the same scale. Furthermore, we study the influence of solvation using the efficient nuclei-selected algorithm to obtain hyperfine coupling constants with electron correlation for large systems, indicating the necessity to include explicit solvent molecules. Finally, we introduce a composite approach to incorporate all contributions for hyperfine coupling of radicals in solution at comparatively low computational cost. This is successfully tested on the hydroxylated TEMPO radical in aqueous solution, where we are able to compute aN-HFCC of 44.4 MHz compared to the experimentally measured 47.6 MHz. [GRAPHICS] .},

keywords = {Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Determination of Nanoscale Mechanical Properties of Polymers via Plasmonic Nanoantennas},

author = {H D Boggiano and R Berte and A F Scarpettini and E Cortes and S A Maier and A V Bragas},

url = {\<Go to ISI\>://WOS:000542931300008},

doi = {10.1021/acsphotonics.0c00631},

issn = {2330-4022},

year  = {2020},

date = {2020-06-02},

journal = {Acs Photonics},

volume = {7},

number = {6},

pages = {1403-1409},

abstract = {Nanotechnology and the consequent emergence of miniaturized devices are driving the need to improve our understanding of the mechanical properties of a myriad of materials. Here we focus on amorphous polymeric materials and introduce a new way to determine the nanoscale mechanical response of polymeric thin films in the GHz range, using ultrafast optical means. Coupling of the films to plasmonic nanoantennas excited at their vibrational eigenfrequencies allows the extraction of the values of the mechanical moduli as well as the estimation of the glass transition temperature via time-domain measurements, here demonstrated for PMMA films. This nanoscale method can be extended to the determination of mechanical and elastic properties of a wide range of spatially strongly confined materials.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Atomic Layer Deposition Assisted Encapsulation of Quantum Dot Luminescent Microspheres toward Display Applications},

author = {F Fang and M J Liu and W Chen and H C Yang and Y Z Liu and X Li and J J Hao and B Xu and D Wu and K Cao and W Lei and P Muller-Buschbaum and X W Sun and R Chen and K Wang},

url = {\<Go to ISI\>://WOS:000528492300001},

doi = {10.1002/adom.201902118},

issn = {2195-1071},

year  = {2020},

date = {2020-06-01},

journal = {Advanced Optical Materials},

volume = {8},

number = {12},

abstract = {Quantum dots (QDs) are promising for being used in advanced displays due to their outstanding emission properties. Herein, a novel encapsulation method for QDs is reported and ultra-stable QDs@SiO2@Al2O3 luminescent microspheres (QLuMiS) are obtained by combining a sol-gel method for the intermediate SiO2 layer with a fluidized powder atomic layer deposition (ALD) for the outer Al2O3 layer. The rich hydroxyl coverage on the QDs@SiO2 surface provides abundant chemisorption sites, which are beneficial for the deposition of Al2O3 in the ALD process. Simultaneously, the water-oxygen channels in the SiO2 layer are blocked by the Al2O3 layer, which protects the QDs against deterioration. Consequently, the QLuMiS exhibit an excellent stability with 86% of the initial light conversion efficiency after 1000 h of blue light aging under a light power density of 2000 mW cm(-2). Such stability is significantly better than that of QDs@Al2O3 and QDs@SiO2 samples. Moreover, under this strong irradiation aging condition with blue light, the extrapolated lifetime (L50) of QLuMiS is 4969 h, which is ten times longer than that of QDs@SiO2 and is the best record as far as is known. Finally, a prototype of a QLuMiS-based cellphone screen with a wide color gamut of 115% NTSC is demonstrated.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Following in Operando the Structure Evolution-Induced Degradation in Printed Organic Solar Cells with Nonfullerene Small Molecule Acceptor},

author = {K S Wienhold and W Chen and S S Yin and R J Guo and M Schwartzkopf and S V Roth and P Muller-Buschbaum},

url = {\<Go to ISI\>://WOS:000538529300001},

doi = {10.1002/solr.202000251},

issn = {2367-198X},

year  = {2020},

date = {2020-06-01},

urldate = {2020-06-01},

journal = {Solar Rrl},

abstract = {Understanding the degradation mechanisms of printed bulk-heterojunction (BHJ) organic solar cells during operation is essential to achieve long-term stability and realize real-world applications of organic photovoltaics. Herein, the degradation of printed organic solar cells based on the conjugated benzodithiophene polymer PBDB-T-SF and the nonfullerene small molecule acceptor IT-4F with 0.25 vol% 1,8-diiodooctane (DIO) solvent additive is studied in operando for two different donor:acceptor ratios. The inner nano-morphology is analyzed with grazing incidence small angle X-ray scattering (GISAXS), and current-voltage (I-V) characteristics are probed simultaneously. Irrespective of the mixing ratio, degradation occurs by the same degradation mechanism. A decrease in the short-circuit current density (J(SC)) is identified to be the determining factor for the decline of the power conversion efficiency. The decrease in J(SC) is induced by a reduction of the relative interface area between the conjugated polymer and the small molecule acceptor in the BHJ structure, resembling the morphological degradation of the active layer.},

keywords = {Foundry Organic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Freestanding LiFe0.2Mn0.8PO4/rGO nanocomposites as high energy density fast charging cathodes for lithium-ion batteries},

author = {F Zoller and D B\"{o}hm and J Luxa and M D\"{o}blinger and Z Sofer and D Semenenko and T Bein and D Fattakhova-Rohlfing},

url = {https://www.sciencedirect.com/science/article/pii/S2468606920300356},

doi = {https://doi.org/10.1016/j.mtener.2020.100416},

issn = {2468-6069},

year  = {2020},

date = {2020-06-01},

journal = {Materials Today Energy},

volume = {16},

pages = {100416},

abstract = {Freestanding electrodes for lithium ion batteries are considered as a promising option to increase the total gravimetric energy density of the cells due to a decreased weight of electrochemically inactive materials. We report a simple procedure for the fabrication of freestanding LiFe0.2Mn0.8PO4 (LFMP)/rGO electrodes with a very high loading of active material of 83 wt%, high total loading of up to 8 mg cm−2, high energy density, excellent cycling stability and at the same time very fast charging rate, with a total performance significantly exceeding the values reported in the literature. The keys to the improved electrode performance are optimization of LFMP nanoparticles via nanoscaling and doping; the use of graphene oxide (GO) with its high concentration of surface functional groups favoring the adhesion of high amounts of LFMP nanoparticles, and freeze-casting of the GO-based nanocomposites to prevent the morphology collapse and provide a unique fluffy open microstructure of the freestanding electrodes. The rate and the cycling performance of the obtained freestanding electrodes are superior compared to their Al-foil coated equivalents, especially when calculated for the entire weight of the electrode, due to the extremely reduced content of electrochemically inactive material (17 wt% of electrochemically inactive material in case of the freestanding compared to 90 wt% for the Al-foil based electrode), resulting in 120 mAh g−1electrode in contrast to 10 mAh g−1electrode at 0.2 C. The electrochemical performance of the freestanding LFMP/rGO electrodes is also considerably better than the values reported in literature for freestanding LFMP and LMP composites, and can even keep up with those of LFP-based analogues. The freestanding LFMP/rGO reported in this work is additionally attractive due to its high gravimetric energy density (604 Wh kg−1LFMP at 0.2C). The obtained results demonstrate the advantage of freestanding LiFe0.2Mn0.8PO4/rGO electrodes and their great potential for applications in lithium ion batteries.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Regio- and diastereoselective reactions of chiral secondary alkylcopper reagents with propargylic phosphates: preparation of chiral allenes},

author = {J Skotnitzki and A Kremsmair and D Keefer and F Schuppel and B L De Bonneville and R De Vivie-Riedle and P Knochel},

url = {\<Go to ISI\>://WOS:000537133000020},

doi = {10.1039/c9sc05982b},

issn = {2041-6520},

year  = {2020},

date = {2020-05-28},

journal = {Chemical Science},

volume = {11},

number = {20},

pages = {5328-5332},

abstract = {The diastereoselective S(N)2 '-substitution of secondary alkylcopper reagents with propargylic phosphates enables the preparation of stereodefined alkylallenes. By using enantiomerically enriched alkylcopper reagents and enantioenriched propargylic phosphates as electrophiles anti-S(N)2 '-substitutions were performend leading to alpha-chiral allenes in good yields with excellent regioselectivity and retention of configuration. DFT-calculations were performed to rationalize the structure of these alkylcopper reagents in various solvents, emphasizing their configurational stability in THF.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Transfer of Direct to Indirect Bound Excitons by Electron Intervalley Scattering in Cs2AgBiBr6 Double Perovskite Nanocrystals},

author = {A Dey and A F Richter and T Debnath and H Huang and L Polavarapu and J Feldmann},

url = {\<Go to ISI\>://WOS:000537682300069},

doi = {10.1021/acsnano.0c00997},

issn = {1936-0851},

year  = {2020},

date = {2020-05-26},

journal = {Acs Nano},

volume = {14},

number = {5},

pages = {5855-5861},

abstract = {Lead-free halide double perovskites have emerged as a nontoxic alternative to the heavily researched lead-based halide perovskites. However, their optical properties and the initial charge carrier relaxation processes are under debate. In this study, we apply time-resolved photoluminescence and differential transmission spectroscopy to investigate the photoexcited charge carrier dynamics within the indirect band structure of Cs2AgBiBr6 nanocrystals. Interestingly, we observe a high energetic emission stemming from the direct band gap, besides the previously reported emission from the indirect band gap transition. We attribute this emission to the radiative recombination of direct bound excitons. This emission maximum redshifts nearly 1 eV within 10 ps due to electron intervalley scattering, which leads to a transfer of direct to indirect bound excitons. We conclude that these direct bound excitons possess a giant oscillator strength causing not only a pronounced absorption peak at the optical band gap energy but also luminescence to occur at the direct band gap transition in spite of the prevailing intervalley scattering process. These results expand the understanding of the optical properties and the charge carrier relaxation in double perovskites, thus, facilitating the further development of optoelectronic devices harnessing lead-free perovskites.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Prospects of Value-Added Chemicals and Hydrogen via Electrolysis},

author = {B Garlyyev and S Xue and J Fichtner and A S Bandarenka and C Andronescu},

url = {\<Go to ISI\>://WOS:000520259100001},

doi = {10.1002/cssc.202000339},

issn = {1864-5631},

year  = {2020},

date = {2020-05-22},

journal = {Chemsuschem},

volume = {13},

number = {10},

pages = {2513-2521},

abstract = {Cost is a major drawback that limits the industrial-scale hydrogen production through water electrolysis. The overall cost of this technology can be decreased by coupling the electrosynthesis of value-added chemicals at the anode side with electrolytic hydrogen generation at the cathode. This Minireview provides a directory of anodic oxidation reactions that can be combined with cathodic hydrogen generation. The important parameters for selecting the anodic reactions, such as choice of catalyst material and its selectivity towards specific products are elaborated in detail. Furthermore, various novel electrolysis cell architectures for effortless separation of value-added products from hydrogen gas are described.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Flexible low-voltage high-frequency organic thin-film transistors},

author = {J W Borchert and U Zschieschang and F Letzkus and M Giorgio and R T Weitz and M Caironi and J N Burghartz and S Ludwigs and H Klauk},

url = {\<Go to ISI\>://WOS:000537235300049},

doi = {10.1126/sciadv.aaz5156},

issn = {2375-2548},

year  = {2020},

date = {2020-05-20},

urldate = {2020-05-20},

journal = {Science Advances},

volume = {6},

number = {21},

abstract = {The primary driver for the development of organic thin-film transistors (TFTs) over the past few decades has been the prospect of electronics applications on unconventional substrates requiring low-temperature processing. A key requirement for many such applications is high-frequency switching or amplification at the low operating voltages provided by lithium-ion batteries (similar to 3 V). To date, however, most organic-TFT technologies show limited dynamic performance unless high operating voltages are applied to mitigate high contact resistances and large parasitic capacitances. Here, we present flexible low-voltage organic TFTs with record static and dynamic performance, including contact resistance as small as 10 Omega.cm, on/off current ratios as large as 10(10), subthreshold swing as small as 59 mV/decade, signal delays below 80 ns in inverters and ring oscillators, and transit frequencies as high as 21 MHz, all while using an inverted coplanar TFT structure that can be readily adapted to industry-standard lithographic techniques.},

keywords = {Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Light-matter interaction in van der Waals hetero-structures},

author = {T Deilmann and M Rohlfing and U Wurstbauer},

url = {\<Go to ISI\>://WOS:000536663700001},

doi = {10.1088/1361-648X/ab8661},

issn = {0953-8984},

year  = {2020},

date = {2020-05-15},

urldate = {2020-05-15},

journal = {Journal of Physics-Condensed Matter},

volume = {32},

number = {33},

abstract = {Even if individual two-dimensional materials own various interesting and unexpected properties, the stacking of such layers leads to van der Waals solids which unite the characteristics of two dimensions with novel features originating from the interlayer interactions. In this topical review, we cover fabrication and characterization of van der Waals hetero-structures with a focus on hetero-bilayers made of monolayers of semiconducting transition metal dichalcogenides. Experimental and theoretical techniques to investigate those hetero-bilayers are introduced. Most recent findings focusing on different transition metal dichalcogenides hetero-structures are presented and possible optical transitions between different valleys, appearance of moire patterns and signatures of moire excitons are discussed. The fascinating and fast growing research on van der Waals hetero-bilayers provide promising insights required for their application as emerging quantum-nano materials.},

keywords = {Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {How the Nature of the Alkali Metal Cations Influences the Double-Layer Capacitance of Cu, Au, and Pt Single-Crystal Electrodes},

author = {S Xue and B Garlyyev and A Auer and J Kunze-Liebhauser and A S Bandarenka},

url = {\<Go to ISI\>://WOS:000541745800029},

doi = {10.1021/acs.jpcc.0c01715},

issn = {1932-7447},

year  = {2020},

date = {2020-05-09},

journal = {Journal of Physical Chemistry C},

volume = {124},

number = {23},

pages = {12442-12447},

abstract = {In this work, we have investigated the influence of alkali metal cations on the electrical double-layer (EDL) properties for various metal electrodes. Using electrochemical impedance spectroscopy, we demonstrate that those cations significantly affect the EDL capacitance in the case of single-crystalline Cu(111), Cu(100), Au(111), Pt(111), stepped Pt(775), and kinked Pt(12 10 5) electrodes in 0.05 M MeClO4 (Me+ = Li+, Na+, K+, Rb+, and Cs+) electrolytes. For all the electrodes, the capacitance always linearly increases with decreasing hydration energy of Me+ in the following order: Li+ \< Na+ \< K+ \< Rb+ \< Cs+. Moreover, we estimate the effective concentrations of the alkali metal cations near the electrode surfaces by correlating the capacitances with the relative permittivity. For all the electrodes, the concentrations near the electrode surface were calculated to be similar to 60 to 80 times higher than in the bulk solutions.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Nonradiative Energy Transfer between Thickness-Controlled Halide Perovskite Nanoplatelets},

author = {A Singldinger and M Gramlich and C Gruber and C Lampe and A S Urban},

url = {\<Go to ISI\>://WOS:000535176100006},

doi = {10.1021/acsenergylett.0c00471},

issn = {2380-8195},

year  = {2020},

date = {2020-05-08},

journal = {Acs Energy Letters},

volume = {5},

number = {5},

pages = {1380-1385},

abstract = {Despite showing great promise for optoelectronics, the commercialization of halide perovskite nanostructure-based devices is hampered by inefficient electrical excitation and strong exciton binding energies. While transport of excitons in an energy-tailored system via Forster resonance energy transfer (FRET) could be an efficient alternative, halide ion migration makes the realization of cascaded structures difficult. Here, we show how these could be obtained by exploiting the pronounced quantum confinement effect in two-dimensional CsPbBr3-based nanoplatelets (NPls). In thin films of NPls of two predetermined thicknesses, we observe an enhanced acceptor photoluminescence (PL) emission and a decreased donor PL lifetime. This indicates a FRET-mediated process, benefitted by the structural parameters of the NPls. We determine corresponding transfer rates up to k(FRET) = 0.99 ns(-1) and efficiencies of nearly eta(FRET) = 70%. We also show FRET to occur between perovskite NPls of other thicknesses. Consequently, this strategy could lead to tailored energy cascade nanostructures for improved optoelectronic devices.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}