Publikationen

@article{nokey,

title = {Electrochemical top-down synthesis of C-supported Pt nano-particles with controllable shape and size: Mechanistic insights and application},

author = {B Garlyyev and S Watzele and J Fichtner and J Michali\v{c}ka and A Sch\"{o}kel and A Senyshyn and A Perego and D Pan and H A El-Sayed and J M Macak and P Atanassov and I V Zenyuk and A S Bandarenka},

url = {https://doi.org/10.1007/s12274-020-3281-z},

doi = {10.1007/s12274-020-3281-z},

issn = {1998-0000},

year  = {2020},

date = {2020-12-29},

journal = {Nano Research},

volume = {14},

number = {8},

pages = {2762-2769},

abstract = {In this work, we demonstrate the power of a simple top-down electrochemical erosion approach to obtain Pt nanoparticle with controlled shapes and sizes (in the range from ~ 2 to ~ 10 nm). Carbon supported nanoparticles with narrow size distributions have been synthesized by applying an alternating voltage to macroscopic bulk platinum structures, such as disks or wires. Without using any surfactants, the size and shape of the particles can be changed by adjusting simple parameters such as the applied potential, frequency and electrolyte composition. For instance, application of a sinusoidal AC voltage with lower frequencies results in cubic nanoparticles; whereas higher frequencies lead to predominantly spherical nanoparticles. On the other hand, the amplitude of the sinusoidal signal was found to affect the particle size; the lower the amplitude of the applied AC signal, the smaller the resulting particle size. Pt/C catalysts prepared by this approach showed 0.76 A/mg mass activity towards the oxygen reduction reaction which is ~ 2 times higher than the state-of-the-art commercial Pt/C catalyst (0.42 A/mg) from Tanaka. In addition to this, we discussed the mechanistic insights about the nanoparticle formation pathways.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Challenges in Plasmonic Catalysis},

author = {E Cort\'{e}s and L V Besteiro and A Alabastri and A Baldi and G Tagliabue and A Demetriadou and P Narang},

url = {https://doi.org/10.1021/acsnano.0c08773},

doi = {10.1021/acsnano.0c08773},

issn = {1936-0851},

year  = {2020},

date = {2020-12-22},

urldate = {2020-12-22},

journal = {ACS Nano},

volume = {14},

number = {12},

pages = {16202-16219},

abstract = {The use of nanoplasmonics to control light and heat close to the thermodynamic limit enables exciting opportunities in the field of plasmonic catalysis. The decay of plasmonic excitations creates highly nonequilibrium distributions of hot carriers that can initiate or catalyze reactions through both thermal and nonthermal pathways. In this Perspective, we present the current understanding in the field of plasmonic catalysis, capturing vibrant debates in the literature, and discuss future avenues of exploration to overcome critical bottlenecks. Our Perspective spans first-principles theory and computation of correlated and far-from-equilibrium light\textendashmatter interactions, synthesis of new nanoplasmonic hybrids, and new steady-state and ultrafast spectroscopic probes of interactions in plasmonic catalysis, recognizing the key contributions of each discipline in realizing the promise of plasmonic catalysis. We conclude with our vision for fundamental and technological advances in the field of plasmon-driven chemical reactions in the coming years.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Interfacial Engineering for Improved Photocatalysis in a Charge Storing 2D Carbon Nitride: Melamine Functionalized Poly(heptazine imide)},

author = {J Kr\"{o}ger and A Jim\'{e}nez-Solano and G Savasci and P Rov\'{o} and I Moudrakovski and K K\"{u}ster and H Schlomberg and H A Vignolo-Gonz\'{a}lez and V Duppel and L Grunenberg and C B Dayan and M Sitti and F Podjaski and C Ochsenfeld and B V Lotsch},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202003016},

doi = {https://doi.org/10.1002/aenm.202003016},

issn = {1614-6832},

year  = {2020},

date = {2020-12-21},

journal = {Advanced Energy Materials},

volume = {11},

number = {6},

pages = {2003016},

abstract = {Abstract Carbon nitrides constitute a class of earth-abundant polymeric semiconductors, which have high potential for tunability on a molecular level, despite their high chemical and thermal inertness. Here the first postsynthetic modification of the 2D carbon nitride poly(heptazine imide) (PHI) is reported, which is decorated with terminal melamine (Mel) moieties by a functional group interconversion. The covalent attachment of this group is verified based with a suite of spectroscopic and microscopic techniques supported by quantum\textendashchemical calculations. Using triethanolamine as a sacrificial electron donor, Mel-PHI outperforms most other carbon nitrides in terms of hydrogen evolution rate (5570 µmol h−1 g−1), while maintaining the intrinsic light storing properties of PHI. The origin of the observed superior photocatalytic performance is traced back to a modified surface electronic structure and enhanced interfacial interactions with the amphiphile triethanolamine, which imparts improved colloidal stability to the catalyst particles especially in contrast to methanol used as donor. However, this high activity can be limited by oxidation products of donor reversibly building up at the surface, thus blocking active centers. The findings lay out the importance of surface functionalization to engineer the catalyst\textendashsolution interface, an underappreciated tuning parameter in photocatalytic reaction design.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Optoelectronic processes in covalent organic frameworks},

author = {N Keller and T Bein},

url = {http://dx.doi.org/10.1039/D0CS00793E},

doi = {10.1039/D0CS00793E},

issn = {0306-0012},

year  = {2020},

date = {2020-12-17},

journal = {Chemical Society Reviews},

abstract = {Covalent organic frameworks (COFs) are crystalline porous materials constructed from molecular building blocks using diverse linkage chemistries. Their modular construction system allows not only for tailor-made design but also for an immense variety of building blocks, opening the door to numerous different functionalities and potential applications. As a consequence, a large number of building blocks that can act as light-harvesters, semiconductors, ligands, binding sites or redox centers have recently been integrated into the scaffolds of COFs. This unique combination of reticular chemistry with the molecular control of intrinsic properties paves the way towards the design of new semiconducting materials for (opto-)electronic applications such as sensors, photocatalysts or -electrodes, supercapacitor and battery materials, solar-harvesting devices or light emitting diodes. With new developments regarding the linkage motif, highly stable but still tunable COFs have been developed for applications even under harsh conditions. Further, the molecular stacking modes and distances in the COFs have been investigated as a powerful means to control optical and electrical characteristics of these self-assembled frameworks. Advanced understanding of optoelectronic processes in COFs has enabled their implementation in optoelectronic devices with promising potential for real-world applications. This review highlights the key developments of design concepts for the synthesis of electro- and photoactive COFs as well as our understanding of optoelectronic processes in these frameworks, hence establishing a new paradigm for the rational construction of well-defined novel optoelectronic materials and devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In Situ Study of Order Formation in Mesoporous Titania Thin Films Templated by a Diblock Copolymer during Slot-Die Printing},

author = {N Li and W Chen and L Song and R Guo and M A Scheel and D Yang and V K\"{o}rstgens and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsami.0c18851},

doi = {10.1021/acsami.0c18851},

issn = {1944-8244},

year  = {2020},

date = {2020-12-09},

urldate = {2020-12-09},

journal = {ACS Applied Materials \& Interfaces},

volume = {12},

number = {51},

pages = {57627-57637},

abstract = {Slot-die printing, a large-scale deposition technique, is applied to fabricate mesoporous titania films. Printing is interesting, for example, for scaling up solar cells where titania films with an interconnected mesoporous network and a large surface-to-volume ratio are desired as photoanodes. A fundamental understanding of the structure evolution during printing is of high significance in tailoring these films. In this work, we provide important insights into the self-assembly of the slot-die-printed titania/polystyrene-block-poly(ethylene oxide) (PS-b-PEO) micelles into ordered hybrid structures in real time via in situ grazing-incidence small-angle X-ray scattering (GISAXS). GISAXS allows for tracking both vertical and lateral structure development of the film formation process. In the hybrid film, a face-centered cubic (FCC) structure is preferentially formed at the interfaces with air and with the substrate, while a defect-rich mixed FCC and body-centered cubic (BCC) structure forms in the bulk. After calcination, the surface and inner morphologies of the obtained nanostructured titania films are compared with the spin-coated analogues. In the printed films, the initially formed nanoscale structure of the hybrid film is preserved, and the resulting mesoporous titania film shows a superior order as compared with the spin-coated thin films which can be beneficial for future applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Covalent Graphene-MOF Hybrids for High-Performance Asymmetric Supercapacitors},

author = {K Jayaramulu and M Horn and A Schneemann and H Saini and A Bakandritsos and V Ranc and M Petr and V Stavila and C Narayana and B Scheibe and \v{S} Kment and M Otyepka and N Motta and D Dubal and R Zbo\v{r}il and R A Fischer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202004560},

doi = {https://doi.org/10.1002/adma.202004560},

issn = {0935-9648},

year  = {2020},

date = {2020-12-04},

journal = {Advanced Materials},

volume = {33},

number = {4},

pages = {2004560},

abstract = {Abstract In this work, the covalent attachment of an amine functionalized metal-organic framework (UiO-66-NH2 = Zr6O4(OH)4(bdc-NH2)6; bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) (UiO-Universitetet i Oslo) to the basal-plane of carboxylate functionalized graphene (graphene acid = GA) via amide bonds is reported. The resultant GA@UiO-66-NH2 hybrid displayed a large specific surface area, hierarchical pores and an interconnected conductive network. The electrochemical characterizations demonstrated that the hybrid GA@UiO-66-NH2 acts as an effective charge storing material with a capacitance of up to 651 F g−1, significantly higher than traditional graphene-based materials. The results suggest that the amide linkage plays a key role in the formation of a π-conjugated structure, which facilitates charge transfer and consequently offers good capacitance and cycling stability. Furthermore, to realize the practical feasibility, an asymmetric supercapacitor using a GA@UiO-66-NH2 positive electrode with Ti3C2TX MXene as the opposing electrode has been constructed. The cell is able to deliver a power density of up to 16 kW kg−1 and an energy density of up to 73 Wh kg−1, which are comparable to several commercial devices such as Pb-acid and Ni/MH batteries. Under an intermediate level of loading, the device retained 88% of its initial capacitance after 10 000 cycles.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Template Dissolution Interfacial Patterning of Single Colloids for Nanoelectrochemistry and Nanosensing},

author = {J B Lee and H Walker and Y Li and T W Nam and A Rakovich and R Sapienza and Y S Jung and Y S Nam and S A Maier and E Cort\'{e}s},

url = {https://doi.org/10.1021/acsnano.0c09319},

doi = {10.1021/acsnano.0c09319},

issn = {1936-0851},

year  = {2020},

date = {2020-12-03},

urldate = {2020-12-03},

journal = {ACS Nano},

abstract = {Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto substrates is a core requirement and a promising alternative to top-down lithography to create functional nanostructures and nanodevices with intriguing optical, electrical, and catalytic features. Capillary-assisted particle assembly (CAPA) has emerged as an attractive technique to this end, as it allows controlled and selective assembly of a wide variety of NPs onto predefined topographical templates using capillary forces. One critical issue with CAPA, however, lies in its final printing step, where high printing yields are possible only with the use of an adhesive polymer film. To address this problem, we have developed a template dissolution interfacial patterning (TDIP) technique to assemble and print single colloidal AuNP arrays onto various dielectric and conductive substrates in the absence of any adhesion layer, with printing yields higher than 98%. The TDIP approach grants direct access to the interface between the AuNP and the target surface, enabling the use of colloidal AuNPs as building blocks for practical applications. The versatile applicability of TDIP is demonstrated by the creation of direct electrical junctions for electro- and photoelectrochemistry and nanoparticle-on-mirror geometries for single-particle molecular sensing.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Time-domain photocurrent spectroscopy based on a common-path birefringent interferometer},

author = {L Wolz and C Heshmatpour and A Perri and D Polli and G Cerullo and J J Finley and E Thyrhaug and J Hauer and A V Stier},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0023543},

doi = {10.1063/5.0023543},

year  = {2020},

date = {2020-12-02},

urldate = {2020-12-02},

journal = {Review of Scientific Instruments},

volume = {91},

number = {12},

pages = {123101},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Spray-deposited PbS colloidal quantum dot solid for near-infrared photodetectors},

author = {W Chen and H Tang and Y Chen and J E Heger and N Li and L P Kreuzer and Y Xie and D Li and C Anthony and Z Pikramenou and K W Ng and X W Sun and K Wang and P M\"{u}ller-Buschbaum},

url = {https://www.sciencedirect.com/science/article/pii/S2211285520308326},

doi = {https://doi.org/10.1016/j.nanoen.2020.105254},

issn = {2211-2855},

year  = {2020},

date = {2020-12-01},

urldate = {2020-12-01},

journal = {Nano Energy},

volume = {78},

pages = {105254},

abstract = {Colloidal PbS quantum dots (QDs) are promising candidates for various optoelectronic applications based on solution-processed thin-film techniques. In this work, a versatile layer-by-layer (LBL) spray deposition of the QDs is introduced aiming for a future large-scale fabrication process of optoelectronic devices. As compared to spin-coated QD solids, a smaller inter-dot distance and a better-ordered superlattice stacking behavior of the QDs are found in the spray-deposited QD solids as confirmed by grazing-incidence small-angle X-ray scattering (GISAXS). The spectral mapping combined time-resolved photoluminescence analysis indicates a longer charge carrier lifetime and better order of the energy state distribution of the spray-deposited QD solid comparing with the spin-coated one. Thus, photodetectors based on spray deposition of QD solids demonstrate an excellent device performance, with the responsivity achieving 365.1 A/W and the detectivity reaching up to 1.4 × 1012 Jones under an illumination power of 63.5 μW/cm2 at a wavelength of 1250 nm. The spray-deposited device performances indicate a great potential of spray deposition of large sized QDs in large-scale fabrications for optoelectronics using longer wavelengths.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Anharmonic host-lattice dynamics enable fast ion conduction in superionic AgI},

author = {T M Brenner and C Gehrmann and R Korobko and T Livneh and D A Egger and O Yaffe},

url = {https://link.aps.org/doi/10.1103/PhysRevMaterials.4.115402},

doi = {10.1103/PhysRevMaterials.4.115402},

year  = {2020},

date = {2020-11-30},

urldate = {2020-11-30},

journal = {Physical Review Materials},

volume = {4},

number = {11},

pages = {115402},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Mode-Matching Enhancement of Second-Harmonic Generation with Plasmonic Nanopatch Antennas},

author = {A Noor and A R Damodaran and I-H Lee and S A Maier and S-H Oh and C Cirac\`{i}},

url = {https://doi.org/10.1021/acsphotonics.0c01545},

doi = {10.1021/acsphotonics.0c01545},

year  = {2020},

date = {2020-11-25},

journal = {ACS Photonics},

volume = {7},

number = {12},

pages = {3333-3340},

abstract = {Plasmonic enhancement of nonlinear optical processes confront severe limitations arising from the strong dispersion of metal susceptibilities and small interaction volumes that hamper the realization of desirable phase-matching-like conditions. Maximizing nonlinear interactions in nanoscale systems require simultaneous excitation of resonant modes that spatially and constructively overlap at all wavelengths involved in the process. Here, we present a hybrid rectangular patch antenna design for optimal second-harmonic generation (SHG) that is characterized by a non-centrosymmetric dielectric/ferroelectric material at the plasmonic hot spot. The optimization of the rectangular patch allows for the independent tuning of various modes of resonances that can be used to enhance the SHG process. We explore the angular dependence of SHG in these hybrid structures and highlight conditions necessary for the maximal SHG efficiency. Furthermore, we propose a novel configuration with a periodically poled ferroelectric layer for an orders-of-magnitude enhanced SHG at normal incidence. Such a platform may enable the development of integrated nanoscale light sources and on-chip frequency converters.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Optoelectronic Properties of Cs2AgBiBr6 Thin Films: The Influence of Precursor Stoichiometry},

author = {M T Sirtl and M Armer and L K Reb and R Hooijer and P D\"{o}rflinger and M A Scheel and K Tvingstedt and P Rieder and N Gl\"{u}ck and P Pandit and S V Roth and P M\"{u}ller-Buschbaum and V Dyakonov and T Bein},

url = {https://doi.org/10.1021/acsaem.0c01308},

doi = {10.1021/acsaem.0c01308},

year  = {2020},

date = {2020-11-25},

journal = {ACS Applied Energy Materials},

abstract = {Lead-free double perovskites have recently attracted growing attention as possible alternatives to lead-based halide perovskites in photovoltaics and other optoelectronic applications. The most prominent compound Cs2AgBiBr6, however, presents issues such as a rather large and indirect band gap, high exciton binding energies, and poor charge carrier transport, especially in thin films. In order to address some of these challenges, we systematically modified the stoichiometry of the precursors used for the synthesis of thin films toward a BiBr3-deficient system. In combination with a stoichiometric excess of AgBr, we obtained highly oriented double perovskite thin films. These modifications directly boost the lifetime of the charge carriers up to 500 ns as observed by time-resolved photoluminescence spectroscopy. Moreover, time-resolved microwave conductivity studies revealed an increase of the charge carrier mobility from 3.5 to around ∼5 cm2/(V s). Solar cells comprising the modified films as planar active layers reached power conversion efficiency (PCE) values up to 1.11%, exceeding the stoichiometric reference film (∼0.97%), both on average and with champion cells. The results in this work underline the importance of controlling the nanomorphology of the bulk film. We anticipate that control of precursor stoichiometry will also offer a promising approach for enhancing the efficiency of other perovskite photovoltaic absorber materials and thin films.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Hierarchical Structures from Nanocrystalline Colloidal Precursors within Hybrid Perovskite Thin Films: Implications for Photovoltaics},

author = {S Pratap and J Schlipf and L Bie\ssmann and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsanm.0c03000},

doi = {10.1021/acsanm.0c03000},

year  = {2020},

date = {2020-11-23},

urldate = {2020-11-23},

journal = {ACS Applied Nano Materials},

volume = {3},

number = {12},

pages = {11701-11708},

abstract = {Originating from stochastic nanocrystalline colloidal precursors with differential chemical compositions, crystalline thin films exhibit hierarchical structures originating at the crystallographic level and scaling up to mesoscale structures, manifested within their nanocrystalline morphology and mesoscale topology. We interlink morphogenetic signatures within thin films to differential precursor chemistry and explain the cooperative impact of structure-defining inorganic and organic counterparts on perovskite hybrids. Understanding the effect of chemical species on the structural characteristics of thin films and leveraging complex assembly processes present facile routes to tuning multiscale morphologies in thin films, pertinent for engineering functional performance metrics within thin-film perovskite photovoltaics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Anharmonic Molecular Motion Drives Resonance Energy Transfer in peri-Arylene Dyads},

author = {V Sl\'{a}ma and V Perl\'{i}k and H Langhals and A Walter and T Man\v{c}al and J Hauer and F \v{S}anda},

url = {https://www.frontiersin.org/article/10.3389/fchem.2020.579166},

doi = {10.3389/fchem.2020.579166},

issn = {2296-2646},

year  = {2020},

date = {2020-11-23},

urldate = {2020-11-23},

journal = {Frontiers in Chemistry},

volume = {8},

abstract = {Spectral and dynamical properties of molecular donor-acceptor systems strongly depend on the steric arrangement of the constituents with exciton coupling J as a key control parameter. In the present work we study two peri-arylene based dyads with orthogonal and parallel transition dipoles for donor and acceptor moieties, respectively. We show that the anharmonic multi-well character of the orthogonal dyad's intramolecular potential explains findings from both stationary and time-resolved absorption experiments. While for a parallel dyad, standard quantum chemical estimates of J at 0 K are in good agreement with experimental observations, J becomes vanishingly small for the orthogonal dyad, in contrast to its ultrafast experimental transfer times. This discrepancy is not resolved even by accounting for harmonic fluctuations along normal coordinates. We resolve this problem by supplementing quantum chemical approaches with dynamical sampling of fluctuating geometries. In contrast to the moderate Gaussian fluctuations of J for the parallel dyad, fluctuations for the orthogonal dyad are found to follow non-Gaussian statistics leading to significantly higher effective J in good agreement with experimental observations. In effort to apply a unified framework for treating the dynamics of optical coherence and excitonic populations of both dyads, we employ a vibronic approach treating electronic and selected vibrational degrees on an equal footing. This vibronic model is used to model absorption and fluorescence spectra as well as donor-acceptor transport dynamics and covers the more traditional categories of F\"{o}rster and Redfield transport as limiting cases.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Self-Regeneration and Self-Healing in DNA Origami Nanostructures},

author = {J M Scheckenbach and P Tinnefeld and V Glembockyte and T Schubert and C Forthmann},

url = {https://doi.org/10.1002/anie.202012986},

doi = {https://doi.org/10.1002/anie.202012986},

issn = {1433-7851},

year  = {2020},

date = {2020-11-23},

journal = {Angewandte Chemie International Edition},

volume = {n/a},

number = {n/a},

abstract = {DNA nanotechnology and advances in the DNA origami technique have enabled facile design and synthesis of complex and functional nanostructures. Molecular devices are, however, prone to rapid functional and structural degradation due to the high proportion of surface atoms at the nanoscale and due to complex working environments. Besides stabilizing mechanisms, approach for the self-repair of functional molecular devices are desirable. Here we exploit the self-assembly and reconfigurability of DNA origami nanostructures to induce the self-repair of defects of photoinduced and enzymatic damage. With different examples of repair in DNA nanostructures, we distinguish between unspecific self-regeneration and damage specific self-healing mechanisms. Using DNA origami nanorulers studied by atomic force and superresolution DNA PAINT microscopy, quantitative preservation of fluorescence properties is demonstrated with direct potential for improving nanoscale calibration samples.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Optoelectronics Meets Optoionics: Light Storing Carbon Nitrides and Beyond},

author = {F Podjaski and B V Lotsch},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202003049},

doi = {https://doi.org/10.1002/aenm.202003049},

issn = {1614-6832},

year  = {2020},

date = {2020-11-23},

journal = {Advanced Energy Materials},

volume = {11},

number = {4},

pages = {2003049},

abstract = {Abstract Known for decades, Liebig's carbon nitrides have evolved into a burgeoning class of macromolecular semiconductors over the past 10+ years, front and center of many efforts revolving around the discovery of resource-efficient and high-performance photocatalysts for solar fuel generation. The recent discovery of a new class of “ionic” 2D carbon nitrides\textemdashpoly(heptazine imide) (PHI)\textemdashhas given new momentum to this field, driven both by unconventional properties and the prospect of new applications at the intersection between solar energy conversion and electrochemical energy storage. In this essay, key concepts of the emerging field of optoionics are delineated and the “light storing” ability of PHI-type carbon nitrides is rationalized by an intricate interplay between their optoelectronic and optoionic properties. Based on these insights, key characteristics and general principles for the de novo design of optoionic materials across the periodic table are derived, opening up new research avenues such as “dark photocatalysis”, direct solar batteries, light-driven autonomous systems, and photomemristive devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Wafer-Scale Epitaxial Positioning of Quantum Dots},

author = {N Bart and C Dangel and P Zajac and N Spitzer and J Ritzmann and M Schmidt and K M\"{u}ller and A Wieck and J J Finley and A Ludwig},

url = {https://arxiv.org/abs/2011.10632v2},

doi = {arXiv:2011.10632v2},

year  = {2020},

date = {2020-11-20},

urldate = {2020-11-20},

journal = {arXiv e-prints},

pages = {arXiv: 2011.10632},

abstract = {Precise control of the properties of semiconductor quantum dots (QDs) is vital for creating novel devices for quantum photonics and advanced opto-electronics. Suitable low QD-density for single QD devices and experiments are challenging to control during epitaxy and are typically found only in limited regions of the wafer. Here, we demonstrate how conventional molecular beam epitaxy (MBE) can be used to modulate the density of optically active QDs in one- and two- dimensional patterns, while still retaining excellent quality. We find that material thickness gradients during layer-by-layer growth result in surface roughness modulations across the whole wafer. Growth on such templates strongly influences the QD nucleation probability. We obtain density modulations between 1 and 10 QDs/μm2 and periods ranging from several millimeters down to at least a few hundred microns. This novel method is universal and expected to be applicable to a wide variety of different semiconductor material systems. We apply the method to enable growth of ultra-low noise QDs across an entire 3-inch semiconductor wafer.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Core\textendashShell Bimetallic Nanoparticle Trimers for Efficient Light-to-Chemical Energy Conversion},

author = {S Lee and H Hwang and W Lee and D Schebarchov and Y Wy and J Grand and B Augui\'{e} and D H Wi and E Cort\'{e}s and S W Han},

url = {https://doi.org/10.1021/acsenergylett.0c02110},

doi = {10.1021/acsenergylett.0c02110},

year  = {2020},

date = {2020-11-19},

journal = {ACS Energy Letters},

pages = {3881-3890},

abstract = {Incorporation of catalytically active materials into plasmonic metal nanostructures can efficiently merge the reactivity and energy-harvesting abilities of both types of materials for visible light photocatalysis. Herein, we explore the influence of electromagnetic hotspots in the ability of plasmonic core\textendashshell colloidal structures to induce chemical transformations. For this study, we developed a synthetic strategy for the fabrication of Au nanoparticle (NP) trimers in aqueous solution through fine controlled galvanic replacement between Ag nanoprisms and Au precursors. Core\textendashshell Au@M NP trimers with catalytically active metals (M = Pd, Pt) were subsequently synthesized using Au NP trimers as templates. Our experimental and computational results highlight the synergy of geometry and composition in plasmonic catalysts for plasmon-driven chemical reactions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Photophysics and Electronic Structure of Lateral Graphene/MoS2 and Metal/MoS2 Junctions},

author = {S Subramanian and Q T Campbell and S K Moser and J Kiemle and P Zimmermann and P Seifert and F Sigger and D Sharma and H Al-Sadeg and M Labella and D Waters and R M Feenstra and R J Koch and C Jozwiak and A Bostwick and E Rotenberg and I Dabo and A W Holleitner and T E Beechem and U Wurstbauer and J A Robinson},

url = {https://doi.org/10.1021/acsnano.0c02527},

doi = {10.1021/acsnano.0c02527},

issn = {1936-0851},

year  = {2020},

date = {2020-11-16},

journal = {ACS Nano},

volume = {14},

number = {12},

pages = {16663-16671},

abstract = {Integration of semiconducting transition metal dichalcogenides (TMDs) into functional optoelectronic circuitries requires an understanding of the charge transfer across the interface between the TMD and the contacting material. Here, we use spatially resolved photocurrent microscopy to demonstrate electronic uniformity at the epitaxial graphene/molybdenum disulfide (EG/MoS2) interface. A 10× larger photocurrent is extracted at the EG/MoS2 interface when compared to the metal (Ti/Au)/MoS2 interface. This is supported by semi-local density functional theory (DFT), which predicts the Schottky barrier at the EG/MoS2 interface to be ∼2× lower than that at Ti/MoS2. We provide a direct visualization of a 2D material Schottky barrier through combination of angle-resolved photoemission spectroscopy with spatial resolution selected to be ∼300 nm (nano-ARPES) and DFT calculations. A bending of ∼500 meV over a length scale of ∼2\textendash3 μm in the valence band maximum of MoS2 is observed via nano-ARPES. We explicate a correlation between experimental demonstration and theoretical predictions of barriers at graphene/TMD interfaces. Spatially resolved photocurrent mapping allows for directly visualizing the uniformity of built-in electric fields at heterostructure interfaces, providing a guide for microscopic engineering of charge transport across heterointerfaces. This simple probe-based technique also speaks directly to the 2D synthesis community to elucidate electronic uniformity at domain boundaries alongside morphological uniformity over large areas.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Photophysics and Electronic Structure of Lateral Graphene/MoS2 and Metal/MoS2 Junctions},

author = {S Subramanian and Q T Campbell and S K Moser and J Kiemle and P Zimmermann and P Seifert and F Sigger and D Sharma and H Al-Sadeg and M Labella and D Waters and R M Feenstra and R J Koch and C Jozwiak and A Bostwick and E Rotenberg and I Dabo and A W Holleitner and T E Beechem and U Wurstbauer and J A Robinson},

url = {https://doi.org/10.1021/acsnano.0c02527},

doi = {10.1021/acsnano.0c02527},

issn = {1936-0851},

year  = {2020},

date = {2020-11-16},

journal = {ACS Nano},

abstract = {Integration of semiconducting transition metal dichalcogenides (TMDs) into functional optoelectronic circuitries requires an understanding of the charge transfer across the interface between the TMD and the contacting material. Here, we use spatially resolved photocurrent microscopy to demonstrate electronic uniformity at the epitaxial graphene/molybdenum disulfide (EG/MoS2) interface. A 10× larger photocurrent is extracted at the EG/MoS2 interface when compared to the metal (Ti/Au)/MoS2 interface. This is supported by semi-local density functional theory (DFT), which predicts the Schottky barrier at the EG/MoS2 interface to be ∼2× lower than that at Ti/MoS2. We provide a direct visualization of a 2D material Schottky barrier through combination of angle-resolved photoemission spectroscopy with spatial resolution selected to be ∼300 nm (nano-ARPES) and DFT calculations. A bending of ∼500 meV over a length scale of ∼2\textendash3 μm in the valence band maximum of MoS2 is observed via nano-ARPES. We explicate a correlation between experimental demonstration and theoretical predictions of barriers at graphene/TMD interfaces. Spatially resolved photocurrent mapping allows for directly visualizing the uniformity of built-in electric fields at heterostructure interfaces, providing a guide for microscopic engineering of charge transport across heterointerfaces. This simple probe-based technique also speaks directly to the 2D synthesis community to elucidate electronic uniformity at domain boundaries alongside morphological uniformity over large areas.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {V(III)-Doped Nickel Oxide-Based Nanocatalysts for Electrochemical Water Splitting: Influence of Phase, Composition, and Doping on the Electrocatalytic Activity},

author = {D B\"{o}hm and M Beetz and C Kutz and S Zhang and C Scheu and T Bein and D Fattakhova-Rohlfing},

url = {https://doi.org/10.1021/acs.chemmater.0c02851},

doi = {10.1021/acs.chemmater.0c02851},

issn = {0897-4756},

year  = {2020},

date = {2020-11-16},

journal = {Chemistry of Materials},

volume = {32},

number = {24},

pages = {10394-10406},

abstract = {Doped nickel oxide-based compounds are attracting great interest as very efficient and abundant catalysts and were thoroughly investigated as battery materials in the past. However, there is still no clear understanding of the influence of dopants on the complex dynamic character of their chemically and potentially driven transformations. We have developed a synthesis procedure enabling the controlled formation of nanosized nickel hydroxide and nickel oxide polymorphs substituted with vanadium(III) [V(III)] ions and further investigated their structure\textendashactivity correlation for electrochemical water oxidation. This work therefore primarily focuses on an in-depth structural characterization of the homogeneously doped nanosized α- and β-Ni(OH)2 polymorphs. It could be shown that concentrations of 10 at. % V(III) and higher can effectively inhibit a spontaneous phase transformation known as chemical aging of the turbostratic α-phase to the more crystalline β-Ni(OH)2 phase in neutral aqueous media. The Fe-impurity-biased electrocatalytic activity determined for α-/β-Ni1\textendashxVx(OH)2 showed only a minor increase of 10% oxygen evolution reaction (OER) activity for an 1 at. % doped nonaged sample resembling the α-phase, while a 5 at. % V(III)-doped sample chemically aged over 24 h led to a doubled OER activity versus the undoped reference which transformed into β-Ni(OH)2 over that period of time.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Sodium Dodecylbenzene Sulfonate Interface Modification of Methylammonium Lead Iodide for Surface Passivation of Perovskite Solar Cells},

author = {Y Zou and R Guo and A Buyruk and W Chen and T Xiao and S Yin and X Jiang and L P Kreuzer and C Mu and T Ameri and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsami.0c14732},

doi = {10.1021/acsami.0c14732},

issn = {1944-8244},

year  = {2020},

date = {2020-11-15},

journal = {ACS Applied Materials \& Interfaces},

volume = {12},

number = {47},

pages = {52643-52651},

abstract = {Perovskite solar cells (PSCs) have been developed as a promising photovoltaic technology because of their excellent photovoltaic performance. However, interfacial recombination and charge carrier transport losses at the surface greatly limit the performance and stability of PSCs. In this work, the fabrication of high-quality PSCs based on methylammonium lead iodide with excellent ambient stability is reported. An anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), is introduced to simultaneously passivate the defect states and stabilize the cubic phase of the perovskite film. The SDBS located at grain boundaries and the surface of the active layer can effectively passivate under-coordinated lead ions and protect the perovskite components from water-induced degradation. As a result, a champion power conversion efficiency (PCE) of 19.42% is achieved with an open-circuit voltage (VOC) of 1.12 V, a short-circuit current (JSC) of 23.23 mA cm\textendash2, and a fill factor (FF) of 74% in combination with superior moisture stability. The SDBS-passivated devices retain 80% of their initial average PCE after 2112 h of storage under ambient conditions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Room-Temperature Synthesis of 2D Janus Crystals and their Heterostructures},

author = {D B Trivedi and G Turgut and Y Qin and M Y Sayyad and D Hajra and M Howell and L Liu and S Yang and N H Patoary and H Li and M M Petri\'{c} and M Meyer and M Kremser and M Barbone and G Soavi and A V Stier and K M\"{u}ller and S Yang and I S Esqueda and H Zhuang and J J Finley and S Tongay},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202006320},

doi = {https://doi.org/10.1002/adma.202006320},

issn = {0935-9648},

year  = {2020},

date = {2020-11-11},

journal = {Advanced Materials},

volume = {32},

number = {50},

pages = {2006320},

abstract = {Abstract Janus crystals represent an exciting class of 2D materials with different atomic species on their upper and lower facets. Theories have predicted that this symmetry breaking induces an electric field and leads to a wealth of novel properties, such as large Rashba spin\textendashorbit coupling and formation of strongly correlated electronic states. Monolayer MoSSe Janus crystals have been synthesized by two methods, via controlled sulfurization of monolayer MoSe2 and via plasma stripping followed thermal annealing of MoS2. However, the high processing temperatures prevent growth of other Janus materials and their heterostructures. Here, a room-temperature technique for the synthesis of a variety of Janus monolayers with high structural and optical quality is reported. This process involves low-energy reactive radical precursors, which enables selective removal and replacement of the uppermost chalcogen layer, thus transforming classical transition metal dichalcogenides into a Janus structure. The resulting materials show clear mixed character for their excitonic transitions, and more importantly, the presented room-temperature method enables the demonstration of first vertical and lateral heterojunctions of 2D Janus TMDs. The results present significant and pioneering advances in the synthesis of new classes of 2D materials, and pave the way for the creation of heterostructures from 2D Janus layers.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Improved Projection-Operator Diabatization Schemes for the Calculation of Electronic Coupling Values},

author = {S Ghan and C Kunkel and K Reuter and H Oberhofer},

url = {https://doi.org/10.1021/acs.jctc.0c00887},

doi = {10.1021/acs.jctc.0c00887},

issn = {1549-9618},

year  = {2020},

date = {2020-11-10},

urldate = {2020-11-10},

journal = {Journal of Chemical Theory and Computation},

volume = {16},

number = {12},

pages = {7431-7443},

abstract = {We address a long-standing ambiguity in the DFT-based projection-operator diabatization method for charge transfer couplings in donor\textendashacceptor systems. It has long been known that the original method yields diabats which are not strictly fragment-localized due to mixing arising from basis-set orthogonalization. We demonstrate that this can contribute to a severe underestimation of coupling strengths and a spurious dependence on the choice of the basis set. As a remedy, we reformulate the method within a simple tight-binding model to generate diabats with increased localization, yielding a proper basis set convergence and improved performance for the general Hab11 benchmark set. Orthogonality of diabats is ensured either through symmetric L\"{o}wdin or asymmetric Gram-Schmid procedures, the latter of which offers to extend these improvements to asymmetric systems such as adsorbates on surfaces.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Solving the COF trilemma: towards crystalline, stable and functional covalent organic frameworks},

author = {F Haase and B V Lotsch},

url = {http://dx.doi.org/10.1039/D0CS01027H},

doi = {10.1039/D0CS01027H},

issn = {0306-0012},

year  = {2020},

date = {2020-11-06},

journal = {Chemical Society Reviews},

abstract = {Covalent organic frameworks (COFs) have entered the stage as a new generation of porous polymers which stand out by virtue of their crystallinity, diverse framework topologies and accessible pore systems. An important \textendash but still underdeveloped \textendash feature of COFs is their potentially superior stability in comparison to other porous materials. Achieving COFs which are simultaneously crystalline, stable, and functional is still challenging as reversible bond formation is one of the prime prerequisites for the crystallization of COFs. However, as the COF field matures new strategies have surfaced that bypass this crystallinity \textendash stability dichotomy. Three major approaches for obtaining both stable and crystalline COFs have taken form in recent years: Tweaking the reaction conditions for reversible linkages, separating the order inducing step and the stability inducing step, and controlling the structural degrees of freedom during assembly and in the final COF. This review discusses rational approaches to stability and crystallinity engineering in COFs, which are apt at overcoming current challenges in COF design and open up new avenues to new real-world applications of COFs.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Polymer photocatalysts for solar-to-chemical energy conversion},

author = {T Banerjee and F Podjaski and J Kr\"{o}ger and B P Biswal and B V Lotsch},

url = {https://doi.org/10.1038/s41578-020-00254-z},

doi = {10.1038/s41578-020-00254-z},

issn = {2058-8437},

year  = {2020},

date = {2020-11-05},

journal = {Nature Reviews Materials},

abstract = {Solar-to-chemical energy conversion for the generation of high-energy chemicals is one of the most viable solutions to the quest for sustainable energy resources. Although long dominated by inorganic semiconductors, organic polymeric photocatalysts offer the advantage of a broad, molecular-level design space of their optoelectronic and surface catalytic properties, owing to their molecularly precise backbone. In this Review, we discuss the fundamental concepts of polymeric photocatalysis and examine different polymeric photocatalysts, including carbon nitrides, conjugated polymers, covalent triazine frameworks and covalent organic frameworks. We analyse the photophysical and physico-chemical concepts that govern the photocatalytic performance of these materials, and derive design principles and possible future research directions in this emerging field of ‘soft photocatalysis’.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Quo Vadis Micro-Electro-Mechanical Systems for the Study of Heterogeneous Catalysts Inside the Electron Microscope?},

author = {M Boniface and M Plodinec and R Schl\"{o}gl and T Lunkenbein},

url = {https://doi.org/10.1007/s11244-020-01398-6},

doi = {10.1007/s11244-020-01398-6},

issn = {1572-9028},

year  = {2020},

date = {2020-11-01},

journal = {Topics in Catalysis},

volume = {63},

number = {15},

pages = {1623-1643},

abstract = {During the last decade, modern micro-electro-mechanical systems (MEMS) technology has been used to create cells that can act as catalytic nanoreactors and fit into the sample holders of transmission electron microscopes. These nanoreactors can maintain atmospheric or higher pressures inside the cells as they seal gases or liquids from the vacuum of the TEM column and can reach temperatures exceeding 1000 °C. This has led to a paradigm shift in electron microscopy, which facilitates the local characterization of structural and morphological changes of solid catalysts under working conditions. In this review, we outline the development of state-of-the-art nanoreactor setups that are commercially available and are currently applied to study catalytic reactions in situ or operando in gaseous or liquid environments. We also discuss challenges that are associated with the use of environmental cells. In catalysis studies, one of the major challenge is the interpretation of the results while considering the discrepancies in kinetics between MEMS based gas cells and fixed bed reactors, the interactions of the electron beam with the sample, as well as support effects. Finally, we critically analyze the general role of MEMS based nanoreactors in electron microscopy and catalysis communities and present possible future directions.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {DNA origami nanorulers and emerging reference structures},

author = {M Scheckenbach and J Bauer and J Z\"{a}hringer and F Selbach and P Tinnefeld},

url = {https://doi.org/10.1063/5.0022885},

doi = {10.1063/5.0022885},

year  = {2020},

date = {2020-11-01},

journal = {APL Materials},

volume = {8},

number = {11},

pages = {110902},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Band structure engineering and defect control of Ta3N5 for efficient photoelectrochemical water oxidation},

author = {Y Xiao and C Feng and J Fu and F Wang and C Li and V F Kunzelmann and C-M Jiang and M Nakabayashi and N Shibata and I D Sharp and K Domen and Y Li},

url = {https://doi.org/10.1038/s41929-020-00522-9},

doi = {10.1038/s41929-020-00522-9},

issn = {2520-1158},

year  = {2020},

date = {2020-11-01},

urldate = {2020-11-01},

journal = {Nature Catalysis},

volume = {3},

number = {11},

pages = {932-940},

abstract = {Ta3N5 is a promising photoanode material with a theoretical maximum solar conversion efficiency of 15.9% for photoelectrochemical water splitting. However, the highest applied bias photon-to-current efficiency achieved so far is only 2.72%. To bridge the efficiency gap, effective carrier management strategies for Ta3N5 photoanodes should be developed. Here, we propose to use gradient Mg doping for band structure engineering and defect control of Ta3N5. The gradient Mg doping profile in Ta3N5 induces a gradient of the band edge energetics, which greatly enhances the charge separation efficiency. Furthermore, defect-related recombination is significantly suppressed due to the passivation effect of Mg dopants on deep-level defects and, more importantly, the matching of the gradient Mg doping profile with the distribution of defects within Ta3N5. As a result, a photoanode based on the gradient Mg-doped Ta3N5 delivers a low onset potential of 0.4 V versus that of a reversible hydrogen electrode and a high applied bias photon-to-current efficiency of 3.25 ± 0.05%.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Electron tunneling at the molecularly thin 2D perovskite and graphene van der Waals interface},

author = {K Leng and L Wang and Y Shao and I Abdelwahab and G Grinblat and I Verzhbitskiy and R Li and Y Cai and X Chi and W Fu and P Song and A Rusydi and G Eda and S A Maier and K P Loh},

url = {https://doi.org/10.1038/s41467-020-19331-6},

doi = {10.1038/s41467-020-19331-6},

issn = {2041-1723},

year  = {2020},

date = {2020-10-30},

journal = {Nature Communications},

volume = {11},

number = {1},

pages = {5483},

abstract = {Quasi-two-dimensional perovskites have emerged as a new material platform for optoelectronics on account of its intrinsic stability. A major bottleneck to device performance is the high charge injection barrier caused by organic molecular layers on its basal plane, thus the best performing device currently relies on edge contact. Herein, by leveraging on van der Waals coupling and energy level matching between two-dimensional Ruddlesden-Popper perovskite and graphene, we show that the plane-contacted perovskite and graphene interface presents a lower barrier than gold for charge injection. Electron tunneling across the interface occurs via a gate-tunable, direct tunneling-to-field emission mechanism with increasing bias, and photoinduced charge transfer occurs at femtosecond timescale (~50 fs). Field effect transistors fabricated on molecularly thin Ruddlesden-Popper perovskite using graphene contact exhibit electron mobilities ranging from 0.1 to 0.018 cm2V−1s−1 between 1.7 to 200 K. Scanning tunneling spectroscopy studies reveal layer-dependent tunneling barrier and domain size on few-layered Ruddlesden-Popper perovskite.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Metal Halide Perovskite@Metal-Organic Framework Hybrids: Synthesis, Design, Properties, and Applications},

author = {S K Yadav and G K Grandhi and D P Dubal and J C De Mello and M Otyepka and R Zbo\v{r}il and R A Fischer and K Jayaramulu},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smll.202004891},

doi = {https://doi.org/10.1002/smll.202004891},

issn = {1613-6810},

year  = {2020},

date = {2020-10-30},

journal = {Small},

volume = {16},

number = {47},

pages = {2004891},

abstract = {Abstract Metal halide perovskites (MHPs) have excellent optoelectronic and photovoltaic applications because of their cost-effectiveness, tunable emission, high photoluminescence quantum yields, and excellent charge carrier properties. However, the potential applications of the entire MHP family are facing a major challenge arising from its weak resistance to moisture, polar solvents, temperature, and light exposure. A viable strategy to enhance the stability of MHPs could lie in their incorporation into a porous template. Metal-organic frameworks (MOFs) have outstanding properties, with a unique network of ordered/functional pores, which render them promising for functioning as such a template, accommodating a wide range of MHPs to the nanosized region, alongside minimizing particle aggregation and enhancing the stability of the entrapped species. This review highlights recent advances in design strategies, synthesis, characterization, and properties of various hybrids of MOFs with MHPs. Particular attention is paid to a critical review of the emergence of MHP@MOF for comprehensive studies of next-generation materials for various technological applications including sensors, photocatalysis, encryption/decryption, light-emitting diodes, and solar cells. Finally, by summarizing the state-of-the-art, some promising future applications of reported hybrids are proposed. Considering the inherent correlation and synergic functionalities of MHPs and MOFs, further advancement; new functional materials; and applications can be achieved through designing MHP@MOF hybrids.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Electron tunneling at the molecularly thin 2D perovskite and graphene van der Waals interface},

author = {K Leng and L Wang and Y Shao and I Abdelwahab and G Grinblat and I Verzhbitskiy and R Li and Y Cai and X Chi and W Fu and P Song and A Rusydi and G Eda and S A Maier and K P Loh},

url = {https://doi.org/10.1038/s41467-020-19331-6},

doi = {10.1038/s41467-020-19331-6},

issn = {2041-1723},

year  = {2020},

date = {2020-10-30},

journal = {Nature Communications},

volume = {11},

number = {1},

pages = {5483},

abstract = {Quasi-two-dimensional perovskites have emerged as a new material platform for optoelectronics on account of its intrinsic stability. A major bottleneck to device performance is the high charge injection barrier caused by organic molecular layers on its basal plane, thus the best performing device currently relies on edge contact. Herein, by leveraging on van der Waals coupling and energy level matching between two-dimensional Ruddlesden-Popper perovskite and graphene, we show that the plane-contacted perovskite and graphene interface presents a lower barrier than gold for charge injection. Electron tunneling across the interface occurs via a gate-tunable, direct tunneling-to-field emission mechanism with increasing bias, and photoinduced charge transfer occurs at femtosecond timescale (~50 fs). Field effect transistors fabricated on molecularly thin Ruddlesden-Popper perovskite using graphene contact exhibit electron mobilities ranging from 0.1 to 0.018 cm2V−1s−1 between 1.7 to 200 K. Scanning tunneling spectroscopy studies reveal layer-dependent tunneling barrier and domain size on few-layered Ruddlesden-Popper perovskite.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Deep Learning Total Energies and Orbital Energies of Large Organic Molecules Using Hybridization of Molecular Fingerprints},

author = {O Rahaman and A Gagliardi},

url = {https://doi.org/10.1021/acs.jcim.0c00687},

doi = {10.1021/acs.jcim.0c00687},

issn = {1549-9596},

year  = {2020},

date = {2020-10-29},

journal = {Journal of Chemical Information and Modeling},

volume = {60},

number = {12},

pages = {5971-5983},

abstract = {The ability to predict material properties without the need for resource-consuming experimental efforts can immensely accelerate material and drug discovery. Although ab initio methods can be reliable and accurate in making such predictions, they are computationally too expensive on a large scale. The recent advancements in artificial intelligence and machine learning as well as the availability of large quantum mechanics derived datasets enable us to train models on these datasets as a benchmark and to make fast predictions on much larger datasets. The success of these machine learning models highly depends on the machine-readable fingerprints of the molecules that capture their chemical properties as well as topological information. In this work, we propose a common deep learning-based framework to combine different types of molecular fingerprints to enhance prediction accuracy. A graph neural network (GNN), many-body tensor representation (MBTR), and a set of simple molecular descriptors (MD) were used to predict the total energies, highest occupied molecular orbital (HOMO) energies, and lowest unoccupied molecular orbital (LUMO) energies of a dataset containing ∼62k large organic molecules with complex aromatic rings and remarkably diverse functional groups. The results demonstrate that a combination of best performing molecular fingerprints can produce better results than the individual ones. The simple and flexible deep learning framework developed in this work can be easily adapted to incorporate other types of molecular fingerprints.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Highly conducting Wurster-type twisted covalent organic frameworks},

author = {J M Rotter and R Guntermann and M Auth and A M\"{a}hringer and A Sperlich and V Dyakonov and D D Medina and T Bein},

url = {http://dx.doi.org/10.1039/D0SC03909H},

doi = {10.1039/D0SC03909H},

issn = {2041-6520},

year  = {2020},

date = {2020-10-27},

urldate = {2020-10-27},

journal = {Chemical Science},

volume = {11},

number = {47},

pages = {12843-12853},

abstract = {Covalent organic frameworks (COFs) define a versatile structural paradigm combining attractive properties such as crystallinity, porosity, and chemical and structural modularity which are valuable for various applications. For the incorporation of COFs into optoelectronic devices, efficient charge carrier transport and intrinsic conductivity are often essential. Here, we report the synthesis of two imine-linked two-dimensional COFs, WTA and WBDT, featuring a redox-active Wurster-type motif based on the twisted tetragonal N,N,N′,N′-tetraphenyl-1,4-phenylenediamine node. By condensing this unit with either terephthalaldehyde (TA) or benzodithiophene dialdehyde (BDT), COFs featuring a dual-pore kagome-type structure were obtained as highly crystalline materials with large specific surface areas and mesoporosity. In addition, the experimentally determined high conduction band energies of both COFs render them suitable candidates for oxidative doping. The incorporation of a benzodithiophene linear building block into the COF allows for high intrinsic macroscopic conductivity. Both anisotropic and average isotropic electrical conductivities were determined with van der Pauw measurements using oriented films and pressed pellets, respectively. Furthermore, the impact of different dopants such as F4TCNQ, antimony pentachloride and iodine on the conductivities of the resulting doped COFs was studied. By using the strong organic acceptor F4TCNQ, a massive increase of the radical cation density (up to 0.5 radicals per unit cell) and long-term stable electrical conductivity as high as 3.67 S m−1 were achieved for the anisotropic transport in an oriented film, one of the highest for any doped COF to date. Interestingly, no significant differences between isotropic and anisotropic charge transport were found in films and pressed pellets. This work expands the list of possible building nodes for electrically conducting COFs from planar systems to twisted geometries. The achievement of high and stable electrical conductivity paves the way for possible applications of new COFs in organic (opto)electronics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Growth of Perovskite CsPbBr3 Nanocrystals and Their Formed Superstructures Revealed by In Situ Spectroscopy},

author = {H Huang and M W Feil and S Fuchs and T Debnath and A F Richter and Y Tong and L Wu and Y Wang and M D\"{o}blinger and B Nickel},

url = {https://doi.org/10.1021/acs.chemmater.0c02467},

doi = {10.1021/acs.chemmater.0c02467},

issn = {0897-4756},

year  = {2020},

date = {2020-10-27},

journal = {Chemistry of Materials},

volume = {32},

number = {20},

pages = {8877-8884},

abstract = {Metal halide perovskites have attracted substantial interest because of their promising properties for optoelectronic applications. Despite much progress made in the field, the exact growth mechanism of perovskite nanocrystals (e.g., CsPbBr3) remains elusive and further improvement of their controllable synthesis is challenging. Herein, we point out different phenomena during the processes of growth, cooling, and purification of high-quality CsPbBr3 nanocrystals using in situ photoluminescence spectroscopy. The as-synthesized materials have been further characterized by time-resolved transient differential transmission and photoluminescence spectroscopies. Using X-ray scattering, we confirm that nanocrystals form superstructures during the process of cooling already in dispersion, which is frequently ignored. The purification process is explained using a proposed model based on the self-size-selection. On the one hand, such superstructures pave a potential pathway to the fabrication of high-quality devices such as light-emitting devices. On the other hand, the approach to reveal their formation process benefits the comparison and understanding of the difference between nanocrystals and supercrystals. The fact that superstructures form already during synthesis may also apply to the different perovskite systems and thus help to improve the quality of the as-prepared nanocrystals.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Collective oscillations of globally coupled bistable, nonresonant components},

author = {M Salman and C Bick and K Krischer},

url = {https://link.aps.org/doi/10.1103/PhysRevResearch.2.043125},

doi = {10.1103/PhysRevResearch.2.043125},

year  = {2020},

date = {2020-10-23},

journal = {Physical Review Research},

volume = {2},

number = {4},

pages = {043125},

abstract = {Bistable microelectrodes with an S-shaped current-voltage characteristic have recently been shown to oscillate under current control, when connected in parallel. In other systems with equivalently coupled bistable components, such oscillatory instabilities have not been reported. In this paper, we derive a general criterion for when an ensemble of coupled bistable components may become oscillatorily unstable. Using a general model, we perform a stability analysis of the ensemble equilibria, in which the components always group in three or fewer clusters. Based thereon, we give a necessary condition for the occurrence of collective oscillations. Moreover, we demonstrate that stable oscillations may persist for an arbitrarily large number of components, even though, as we show, any equilibrium with two or more components on the middle, autocatalytic branch is unstable.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Multiscale Conformational Sampling Reveals Excited-State Locality in DNA Self-Repair Mechanism},

author = {V Piccinni and S Reiter and D Keefer and R De Vivie-Riedle},

url = {https://doi.org/10.1021/acs.jpca.0c07207},

doi = {10.1021/acs.jpca.0c07207},

issn = {1089-5639},

year  = {2020},

date = {2020-10-22},

urldate = {2020-10-22},

journal = {The Journal of Physical Chemistry A},

volume = {124},

number = {44},

pages = {9133-9140},

abstract = {Ultraviolet (UV) irradiation is known to be responsible for DNA damage. However, experimental studies in DNA oligonucleotides have shown that UV light can also induce sequence-specific self-repair. Following charge transfer from a guanine adenine sequence adjacent to a cyclobutane pyrimidine dimer (CPD), the covalent bond between the two thymines could be cleaved, recovering the intact base sequence. Mechanistic details promoting the self-repair remained unclear, however. In our theoretical study, we investigated whether optical excitation could directly lead to a charge-transfer state, thereby initiating the repair, or whether the initial excited state remains localized on a single nucleobase. We performed conformational sampling of 200 geometries of the damaged DNA double strand solvated in water and used a hybrid quantum and molecular mechanics approach to compute excited states at the complete active space perturbation level of theory. Analysis of the conformational data set clearly revealed that the excited-state properties are uniformly distributed across the fluctuations of the nucleotide in its natural environment. From the electronic wavefunction, we learned that the electronic transitions remained predominantly local on either adenine or guanine, and no direct charge transfer occurred in the experimentally accessed energy range. The investigated base sequence is not only specific to the CPD repair mechanism but ubiquitously occurs in nucleic acids. Our results therefore give a very general insight into the charge locality of UV-excited DNA, a property that is regarded to have determining relevance in the structural consequences following absorption of UV photons.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Hydrogel-supported graphitic carbon nitride nanosheets loaded with Pt atoms as a novel self-water-storage photocatalyst for H2 evolution},

author = {L Lei and W Wang and C Wang and H Fan and A K Yadav and N Hu and Q Zhong and P M\"{u}ller-Buschbaum},

url = {http://dx.doi.org/10.1039/D0TA07805K},

doi = {10.1039/D0TA07805K},

issn = {2050-7488},

year  = {2020},

date = {2020-10-21},

urldate = {2020-10-21},

journal = {Journal of Materials Chemistry A},

volume = {8},

number = {45},

pages = {23812-23819},

abstract = {Graphitic carbon nitride (g-C3N4) exhibits an excellent photocatalytic performance as a powder, especially under visible light irradiation. However, it encounters great challenges for practical applications. For instance, to avoid aggregation and precipitation, a continuous stirring process is required for the bare g-C3N4 powder during the photocatalytic reaction. In addition, recycling of the powder photocatalyst is complicated and usually not environment friendly. To overcome these drawbacks, we present a hybrid materials. This material combines g-C3N4 nanosheets loaded with cocatalyst Pt atoms (CN) with a polymer hydrogel. In the ready-to-use photocatalyst, CN is well distributed in the hydrogel matrix. Water stored in the hydrogel can serve as a water reservoir for the photocatalytic water splitting. Due to the intermolecular interactions between CN and the hydrogel, a 3D network with a small-sized nanostructure is formed, which enhances the light absorption and the charge carrier separation. As a result, the H2 evolution rate is 7437 μmol h−1 g−1, which is 130% higher than that of the bare CN powder in water. Furthermore, the hydrogel-supported CN is able to function under ambient environment conditions without any significant reduction of the photocatalytic performance, as compared to the bare CN powder. In the hybrid material, the combination of hydrogel and CN provides a possibility for the photocatalyst to work without a water environment and accomplish an efficient H2 evolution.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Internal nanoscale architecture and charge carrier dynamics of wide bandgap non-fullerene bulk heterojunction active layers in organic solar cells},

author = {X Jiang and H Kim and P S Deimel and W Chen and W Cao and D Yang and S Yin and R Schaffrinna and F Allegretti and J V Barth and M Schwager and H Tang and K Wang and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {http://dx.doi.org/10.1039/D0TA09671G},

doi = {10.1039/D0TA09671G},

issn = {2050-7488},

year  = {2020},

date = {2020-10-19},

journal = {Journal of Materials Chemistry A},

volume = {8},

number = {44},

pages = {23628-23636},

abstract = {Bulk heterojunction (BHJ) organic solar cells have gained increasing attention in the past few years. In this work, active layers of a wide-bandgap polymer donor with benzodithiophene units PBDB-T-2F and a non-fullerene small molecule acceptor IT-M are assembled into photovoltaic devices with different amounts of solvent additive 1,8-diiodooctane (DIO). The influence of DIO on the nanoscale film morphology and crystalline structure as well as the charge carrier dynamics of the active layers are investigated by combining grazing-incidence small-angle X-ray scattering (GISAXS), grazing-incidence wide-angle X-ray scattering (GIWAXS), X-ray reflectivity (XRR), UV-visible (UV-vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), time-resolved photoluminescence (TRPL) and space charge limited current measurements, which are correlated with the corresponding performance of the solar cells. At 0.5 vol% DIO addition, the wide-bandgap non-fullerene organic solar cells show the best performance due to high open-circuit voltage and short-circuit current resulting from an improved charge carrier management due to the optimal inner nanoscale morphology of the active layers in terms of surface enrichment, crystallinity and crystalline orientation.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Light\textendashMatter Interaction in Quantum Confined 2D Polar Metals},

author = {K Nisi and S Subramanian and W He and K A Ulman and H El-Sherif and F Sigger and M Lassauni\`{e}re and M T Wetherington and N Briggs and J Gray and A W Holleitner and N Bassim and S Y Quek and J A Robinson and U Wurstbauer},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.202005977},

doi = {https://doi.org/10.1002/adfm.202005977},

issn = {1616-301X},

year  = {2020},

date = {2020-10-15},

urldate = {2020-10-15},

journal = {Advanced Functional Materials},

volume = {n/a},

number = {n/a},

pages = {2005977},

abstract = {Abstract This work is a systematic experimental and theoretical study of the in-plane dielectric functions of 2D gallium and indium films consisting of two or three atomic metal layers confined between silicon carbide and graphene with a corresponding bonding gradient from covalent to metallic to van der Waals type. k-space resolved free electron and bound electron contributions to the optical response are identified, with the latter pointing towards the existence of thickness dependent quantum confinement phenomena. The resonance energies in the dielectric functions and the observed epsilon near-zero behavior in the near infrared to visible spectral range, are dependent on the number of atomic metal layers and properties of the metal involved. A model-based spectroscopic ellipsometry approach is used to estimate the number of atomic metal layers, providing a convenient route over expensive invasive characterization techniques. A strong thickness and metal choice dependence of the light\textendashmatter interaction makes these half van der Waals 2D polar metals attractive for quantum engineered metal films, tunable (quantum-)plasmonics and nano-photonics.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Photobase effect for just-in-time delivery in photocatalytic hydrogen generation},

author = {J Fang and T Debnath and S Bhattacharyya and M D\"{o}blinger and J Feldmann and J K Stolarczyk},

url = {https://doi.org/10.1038/s41467-020-18583-6},

doi = {10.1038/s41467-020-18583-6},

issn = {2041-1723},

year  = {2020},

date = {2020-10-14},

journal = {Nature Communications},

volume = {11},

number = {1},

pages = {5179},

abstract = {Carbon dots (CDs) are a promising nanomaterial for photocatalytic applications. However, the mechanism of the photocatalytic processes remains the subject of a debate due to the complex internal structure of the CDs, comprising crystalline and molecular units embedded in an amorphous matrix, rendering the analysis of the charge and energy transfer pathways between the constituent parts very challenging. Here we propose that the photobasic effect, that is the abstraction of a proton from water upon excitation by light, facilitates the photoexcited electron transfer to the proton. We show that the controlled inclusion in CDs of a model photobase, acridine, resembling the molecular moieties found in photocatalytically active CDs, strongly increases hydrogen generation. Ultrafast spectroscopy measurements reveal proton transfer within 30 ps of the excitation. This way, we use a model system to show that the photobasic effect may be contributing to the photocatalytic H2 generation of carbon nanomaterials and suggest that it may be tuned to achieve further improvements. The study demonstrates the critical role of the understanding the dynamics of the CDs in the design of next generation photocatalysts.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Formation and stability of small polarons at the lithium-terminated Li4Ti5O12 (LTO) (111) surface},

author = {M Kick and C Scheurer and H Oberhofer},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0021443},

doi = {10.1063/5.0021443},

year  = {2020},

date = {2020-10-08},

journal = {The Journal of Chemical Physics},

volume = {153},

number = {14},

pages = {144701},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nanoscale patterning at the Si/SiO2/graphene interface by focused He+ beam},

author = {A B\"{o}ttcher and R Schwaiger and T M Pazdera and D Exner and J Hauns and D Strelnikov and S Lebedkin and R Gr\"{o}ger and F Esch and B A J Lechner},

url = {https://iopscience.iop.org/article/10.1088/1361-6528/abb5cf/meta?casa_token=0ch84-BOwLoAAAAA:0ibNutoV58k0ONYDhRhhBtMaAbaDMOWEDghZKBvbCABbhx1dGH2gGSD1baUoc-Zosx5xyOGgxg},

doi = {10.1088/1361-6528/abb5cf},

issn = {0957-4484},

year  = {2020},

date = {2020-10-06},

urldate = {2020-10-06},

journal = {Nanotechnology},

volume = {31},

number = {50},

pages = {505302},

abstract = {We have studied the capability of He+ focused ion beam (He+-FIB) patterning to fabricate defect arrays on the Si/SiO2/Graphene interface using a combination of atomic force microscopy (AFM) and Raman imaging to probe damage zones. In general, an amorphized 'blister' region of cylindrical symmetry results upon exposing the surface to the stationary focused He+ beam. The topography of the amorphized region depends strongly on the ion dose, DS, (ranging from 103 to 107ions/spot) with craters and holes observed at higher doses. Furthermore, the surface morphology depends on the distance between adjacent irradiated spots, LS. Increasing the dose leads to (enhanced) subsurface amorphization and a local height increase relative to the unexposed regions. At the highest areal ion dose, the average height of a patterned area also increases as ∼1/LS. Correspondingly, in optical micrographs, the µm2-sized patterned surface regions change appearance. These phenomena can be explained by implantation of the He+ ions into the subsurface layers, formation of helium nanobubbles, expansion and modification of the dielectric constant of the patterned material. The corresponding modifications of the terminating graphene monolayer have been monitored by micro Raman imaging. At low ion doses, DS, the graphene becomes modified by carbon atom defects which perturb the 2D lattice (as indicated by increasing D/G Raman mode ratio). Additional x-ray photoionization spectroscopy (XPS) measurements allow us to infer that for moderate ion doses, scattering of He+ ions by the subsurface results in the oxidation of the graphene network. For largest doses and smallest LS values, the He+ beam activates extensive Si/SiO2/C bond rearrangement and a multicomponent material possibly comprising SiC and silicon oxycarbides, SiOC, is observed. We also infer parameter ranges for He+-FIB patterning defect arrays of potential use for pinning transition metal nanoparticles in model studies of heterogeneous catalysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Energy Efficient Ultrahigh Flux Separation of Oily Pollutants from Water with Superhydrophilic Nanoscale Metal\textendashOrganic Framework Architectures},

author = {A M\"{a}hringer and M Hennemann and T Clark and T Bein and D D Medina},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202012428},

doi = {https://doi.org/10.1002/anie.202012428},

issn = {1433-7851},

year  = {2020},

date = {2020-10-05},

journal = {Angewandte Chemie International Edition},

volume = {60},

number = {10},

pages = {5519-5526},

abstract = {Abstract The rising demand for clean water for a growing and increasingly urban global population is one of the most urgent issues of our time. Here, we introduce the synthesis of a unique nanoscale architecture of pillar-like Co-CAT-1 metal\textendashorganic framework (MOF) crystallites on gold-coated woven stainless steel meshes with large, 50 μm apertures. These nanostructured mesh surfaces feature superhydrophilic and underwater superoleophobic wetting properties, allowing for gravity-driven, highly efficient oil\textendashwater separation featuring water fluxes of up to nearly one million L m−2 h−1. Water physisorption experiments reveal the hydrophilic nature of Co-CAT-1 with a total water vapor uptake at room temperature of 470 cm3 g−1. Semiempirical molecular orbital calculations shed light on water affinity of the inner and outer pore surfaces. The MOF-based membranes enable high separation efficiencies for a number of liquids tested, including the notorious water pollutant, crude oil, affording chemical oxygen demand (COD) concentrations below 25 mg L−1 of the effluent. Our results demonstrate the great impact of suitable nanoscale surface architectures as a means of encoding on-surface extreme wetting properties, yielding energy-efficient water-selective large-aperture membranes.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ultrathin catalyst-free InAs nanowires on silicon with distinct 1D sub-band transport properties},

author = {F Del Giudice and J Becker and C De Rose and M D\"{o}blinger and D Ruhstorfer and L Suomenniemi and J Treu and H Riedl and J J Finley and G Koblm\"{u}ller},

url = {http://dx.doi.org/10.1039/D0NR05666A},

doi = {10.1039/D0NR05666A},

issn = {2040-3364},

year  = {2020},

date = {2020-10-01},

journal = {Nanoscale},

volume = {12},

number = {42},

pages = {21857-21868},

abstract = {Ultrathin InAs nanowires (NW) with a one-dimensional (1D) sub-band structure are promising materials for advanced quantum-electronic devices, where dimensions in the sub-30 nm diameter limit together with post-CMOS integration scenarios on Si are much desired. Here, we demonstrate two site-selective synthesis methods that achieve epitaxial, high aspect ratio InAs NWs on Si with ultrathin diameters below 20 nm. The first approach exploits direct vapor\textendashsolid growth to tune the NW diameter by interwire spacing, mask opening size and growth time. The second scheme explores a unique reverse-reaction growth by which the sidewalls of InAs NWs are thermally decomposed under controlled arsenic flux and annealing time. Interesting kinetically limited dependencies between interwire spacing and thinning dynamics are found, yielding diameters as low as 12 nm for sparse NW arrays. We clearly verify the 1D sub-band structure in ultrathin NWs by pronounced conductance steps in low-temperature transport measurements using back-gated NW-field effect transistors. Correlated simulations reveal single- and double degenerate conductance steps, which highlight the rotational hexagonal symmetry and reproduce the experimental traces in the diffusive 1D transport limit. Modelling under the realistic back-gate configuration further evidences regimes that lead to asymmetric carrier distribution and breakdown of the degeneracy depending on the gate bias.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Ultrathin catalyst-free InAs nanowires on silicon with distinct 1D sub-band transport properties},

author = {Del F Giudice and J Becker and De C Rose and M D\"{o}blinger and D Ruhstorfer and L Suomenniemi and J Treu and H Riedl and J J Finley and G Koblm\"{u}ller},

url = {http://dx.doi.org/10.1039/D0NR05666A},

doi = {10.1039/D0NR05666A},

issn = {2040-3364},

year  = {2020},

date = {2020-10-01},

journal = {Nanoscale},

volume = {12},

number = {42},

pages = {21857-21868},

abstract = {Ultrathin InAs nanowires (NW) with a one-dimensional (1D) sub-band structure are promising materials for advanced quantum-electronic devices, where dimensions in the sub-30 nm diameter limit together with post-CMOS integration scenarios on Si are much desired. Here, we demonstrate two site-selective synthesis methods that achieve epitaxial, high aspect ratio InAs NWs on Si with ultrathin diameters below 20 nm. The first approach exploits direct vapor\textendashsolid growth to tune the NW diameter by interwire spacing, mask opening size and growth time. The second scheme explores a unique reverse-reaction growth by which the sidewalls of InAs NWs are thermally decomposed under controlled arsenic flux and annealing time. Interesting kinetically limited dependencies between interwire spacing and thinning dynamics are found, yielding diameters as low as 12 nm for sparse NW arrays. We clearly verify the 1D sub-band structure in ultrathin NWs by pronounced conductance steps in low-temperature transport measurements using back-gated NW-field effect transistors. Correlated simulations reveal single- and double degenerate conductance steps, which highlight the rotational hexagonal symmetry and reproduce the experimental traces in the diffusive 1D transport limit. Modelling under the realistic back-gate configuration further evidences regimes that lead to asymmetric carrier distribution and breakdown of the degeneracy depending on the gate bias.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Nanostructured amorphous gallium phosphide on silica for nonlinear and ultrafast nanophotonics},

author = {B Tilmann and G Grinblat and R Bert\'{e} and M \"{O}zcan and V F Kunzelmann and B Nickel and I D Sharp and E Cort\'{e}s and S A Maier and Y Li},

url = {http://dx.doi.org/10.1039/D0NH00461H},

doi = {10.1039/D0NH00461H},

issn = {2055-6756},

year  = {2020},

date = {2020-09-30},

journal = {Nanoscale Horizons},

volume = {5},

number = {11},

pages = {1500-1508},

abstract = {Nanophotonics based on high refractive index dielectrics relies on appreciable contrast between the indices of designed nanostructures and their immediate surrounding, which can be achieved by the growth of thin films on low-index substrates. Here we propose the use of high index amorphous gallium phosphide (a-GaP), fabricated by radio-frequency sputter deposition, on top of a low refractive index glass substrate and thoroughly examine its nanophotonic properties. Spectral ellipsometry of the amorphous material demonstrates the optical properties to be considerably close to crystalline gallium phosphide (c-GaP), with low-loss transparency for wavelengths longer than 650 nm. When nanostructured into nanopatches, the second harmonic (SH) response of an individual a-GaP patch is characterized to be more than two orders of magnitude larger than the as-deposited unstructured film, with an anapole-like resonant behavior. Numerical simulations are in good agreement with the experimental results over a large spectral and geometrical range. Furthermore, by studying individual a-GaP nanopatches through non-degenerate pump\textendashprobe spectroscopy with sub-10 fs pulses, we find a more than 5% ultrafast modulation of the reflectivity that is accompanied by a slower decaying free carrier contribution, caused by absorption. Our investigations reveal a potential for a-GaP as an adequate inexpensive and CMOS-compatible material for nonlinear nanophotonic applications as well as for photocatalysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {In Situ Quantification of the Local Electrocatalytic Activity via Electrochemical Scanning Tunneling Microscopy},

author = {R W Haid and R M Kluge and Y Liang and A S Bandarenka},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/smtd.202000710},

doi = {https://doi.org/10.1002/smtd.202000710},

issn = {2366-9608},

year  = {2020},

date = {2020-09-29},

journal = {Small Methods},

volume = {5},

number = {2},

pages = {2000710},

abstract = {Abstract Identification of catalytically active sites at solid/liquid interfaces under reaction conditions is an essential task to improve the catalyst design for sustainable energy devices. Electrochemical scanning tunneling microscopy (EC-STM) combines the control of the surface reactions with imaging on a nanoscale. When performing EC-STM under reaction conditions, the recorded analytical signal shows higher fluctuations (noise) at active sites compared to non-active sites (noise-EC-STM or n-EC-STM). In the past, this approach has been proven as a valid tool to identify the location of active sites. In this work, the authors show that this method can be extended to obtain quantitative information of the local activity. For the platinum(111) surface under oxygen reduction reaction conditions, a linear relationship between the STM noise level and a measure of reactivity, the turn-over frequency is found. Since it is known that the most active sites for this system are located at concave sites, the method has been applied to quantify the activity at steps. The obtained activity enhancement factors appeared to be in good agreement with the literature. Thus, n-EC-STM is a powerful method not only to in situ identify the location of active sites but also to determine and compare local reactivity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}