Publications

@article{nokey,

title = {Imaging built-in electric fields and light matter by Fourier-precession TEM},

author = {T Lorenzen and B M\"{a}rz and T Xue and A Beyer and K Volz and T Bein and K M\"{u}ller-Caspary},

url = {https://doi.org/10.1038/s41598-024-51423-x},

doi = {10.1038/s41598-024-51423-x},

issn = {2045-2322},

year  = {2024},

date = {2024-01-15},

journal = {Scientific Reports},

volume = {14},

number = {1},

pages = {1320},

abstract = {We report the precise measurement of electric fields in nanostructures, and high-contrast imaging of soft matter at ultralow electron doses by transmission electron microscopy (TEM). In particular, a versatile method based on the theorem of reciprocity is introduced to enable differential phase contrast imaging and ptychography in conventional, plane-wave illumination TEM. This is realised by a series of TEM images acquired under different tilts, thereby introducing the sampling rate in reciprocal space as a tuneable parameter, in contrast to momentum-resolved scanning techniques. First, the electric field of a p\textendashn junction in GaAs is imaged. Second, low-dose, in-focus ptychographic and DPC characterisation of Kagome pores in weakly scattering covalent organic frameworks is demonstrated by using a precessing electron beam in combination with a direct electron detector. The approach offers utmost flexibility to record relevant spatial frequencies selectively, while acquisition times and dose requirements are significantly reduced compared to the 4D-STEM counterpart.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Please Mind the Gap: Highly Condensed P\textendashN Networks in LiP4N7 and Li3−xP6N11−x(NH)x},

author = {S Schneider and S Klenk and S D Kloss and W Schnick},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202303251},

doi = {https://doi.org/10.1002/chem.202303251},

issn = {0947-6539},

year  = {2024},

date = {2024-01-04},

urldate = {2023-10-24},

journal = {Chemistry \textendash A European Journal},

volume = {30},

pages = {e202303251},

abstract = {Abstract Alkali nitridophosphates AP4N7 and A3P6N11 (A=Na, K, Rb, Cs) have been known for decades. However, their Li homologues have remained elusive. In this work, the highly condensed lithium (imido)nitridophosphates LiP4N7 and Li3−xP6N11−x(NH)x (x=1.66(3)) were synthesized from LiPN2 and P3N5 in the multianvil press at 10 GPa. They constitute the first lithium nitridophosphates with 3D networks exhibiting a degree of condensation larger than 0.5 and high thermal stability. LiP4N7 crystallizes in the orthorhombic space group P212121 with a=4.5846(6) r{A}},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Discovery of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) as promising thermoelectric materials by computational screening},

author = {D Han and B Zhu and Z Cai and K B Spooner and S S Rudel and W Schnick and T Bein and D O Scanlon and H Ebert},

url = {https://www.sciencedirect.com/science/article/pii/S2590238523005234},

doi = {https://doi.org/10.1016/j.matt.2023.10.022},

issn = {2590-2385},

year  = {2024},

date = {2024-01-03},

urldate = {2024-01-03},

journal = {Matter},

volume = {7},

issue = {1},

pages = {158-174},

abstract = {Summary The thermoelectric performance of existing perovskites lags far behind that of state-of-the-art thermoelectric materials such as SnSe. Despite halide perovskites showing promising thermoelectric properties, namely, high Seebeck coefficients and ultralow thermal conductivities, their thermoelectric performance is significantly restricted by low electrical conductivities. Here, we explore new multi-anion antiperovskites X6NFSn2 (X = Ca, Sr, and Ba) via B-site anion mutation in antiperovskite and global structure searches and demonstrate their phase stability by first-principles calculations. Ca6NFSn2 and Sr6NFSn2 exhibit decent Seebeck coefficients and ultralow lattice thermal conductivities (\<1 W m−1 K−1). Notably, Ca6NFSn2 and Sr6NFSn2 show remarkably larger electrical conductivities compared to the halide perovskite CsSnI3. The combined superior electrical and thermal properties of Ca6NFSn2 and Sr6NFSn2 lead to high thermoelectric figures of merit (ZTs) of ∼1.9 and ∼2.3 at high temperatures. Our exploration of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) realizes the “phonon-glass, electron-crystal” concept within the antiperovskite structure.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Combining Nitridoborates, Nitrides and Hydrides\textemdashSynthesis and Characterization of the Multianionic Sr6N[BN2]2H3},

author = {S L Wandelt and A Mutschke and D Khalyavin and R Calaminus and J Steinadler and B V Lotsch and W Schnick},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202313564},

doi = {https://doi.org/10.1002/anie.202313564},

issn = {1433-7851},

year  = {2023},

date = {2023-10-31},

urldate = {2023-10-31},

journal = {Angewandte Chemie International Edition},

volume = {62},

number = {50},

pages = {e202313564},

abstract = {Abstract Multianionic metal hydrides, which exhibit a wide variety of physical properties and complex structures, have recently attracted growing interest. Here we present Sr6N[BN2]2H3, prepared in a solid-state ampoule reaction at 800 °C, as the first combination of nitridoborate, nitride and hydride anions within a single compound. The crystal structure was solved from single-crystal X-ray and neutron powder diffraction data in space group P21/c (no. 14), revealing a three-dimensional network of undulated layers of nitridoborate units, strontium atoms and hydride together with nitride anions. Magic angle spinning (MAS) NMR and vibrational spectroscopy in combination with quantum chemical calculations further confirm the structure model. Electrochemical measurements suggest the existence of hydride ion conductivity, allowing the hydrides to migrate along the layers.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Finding Order in Disorder: The Highly Disordered Lithium Oxonitridophosphate Double Salt Li8+xP3O10−xN1+x (x=1.4(5))},

author = {S Schneider and S T Kreiner and L G Balzat and B V Lotsch and W Schnick},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202301986},

doi = {https://doi.org/10.1002/chem.202301986},

issn = {0947-6539},

year  = {2023},

date = {2023-07-12},

journal = {Chemistry \textendash A European Journal},

volume = {29},

number = {55},

pages = {e202301986},

abstract = {Abstract The crystalline lithium oxonitridophosphate Li8+xP3O10−xN1+x, was obtained in an ampoule synthesis from P3N5 and Li2O. The compound crystallizes in the triclinic space group P with a=5.125(2)},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ionic liquids tailoring crystal orientation and electronic properties for stable perovskite solar cells},

author = {Y Zou and J Eichhorn and S Rieger and Y Zheng and S Yuan and L Wolz and L V Spanier and J E Heger and S Yin and C R Everett and L Dai and M Schwartzkopf and C Mu and S V Roth and I D Sharp and C-C Chen and J Feldmann and S D Stranks and P M\"{u}ller-Buschbaum},

url = {https://www.sciencedirect.com/science/article/pii/S2211285523002860},

doi = {https://doi.org/10.1016/j.nanoen.2023.108449},

issn = {2211-2855},

year  = {2023},

date = {2023-04-21},

journal = {Nano Energy},

volume = {112},

pages = {108449},

abstract = {The crystallization behavior of perovskite films has a profound influence on the resulting defect densities, charge carrier dynamics and photovoltaic performance. Herein, we introduce ionic liquids into the perovskite component to tailor the crystal growth of perovskite films from a disordered to a preferential corner-up orientation and accordingly increase the charge carrier mobility to accelerate electron transport and extraction. Using time-resolved measurements, we probe the charge carrier generation, transport and recombination behavior in these films and related devices. We find the ionic liquid-containing samples exhibit lower defects, faster charge carrier transport and suppressed non-radiative recombination, contributing to higher efficiency and fill factor. Via operando grazing-incidence small- and wide-angle X-ray scattering measurements, we observe a light-induced lattice compression and grain fragmentation in the control devices, whereas the ionic liquid-containing devices exhibit a slight light-induced crystal reconstitution and stronger tolerance against illumination. Under ambient conditions, the non-encapsulated device with the pyrrolidinium-based ionic compound (Pyr14BF4) maintains 97% of its initial efficiency after 4368 h.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Elucidating the Roles of Nafion/Solvent Formulations in Copper-Catalyzed CO2 Electrolysis},

author = {P Ding and H An and P Zellner and T Guan and J Gao and P M\"{u}ller-Buschbaum and B M Weckhuysen and W Van Der Stam and I D Sharp},

url = {https://doi.org/10.1021/acscatal.2c05235},

doi = {10.1021/acscatal.2c05235},

year  = {2023},

date = {2023-04-05},

journal = {ACS Catalysis},

pages = {5336-5347},

abstract = {Nafion ionomer, composed of hydrophobic perfluorocarbon backbones and hydrophilic sulfonic acid side chains, is the most widely used additive for preparing catalyst layers (CLs) for electrochemical CO2 reduction, but its impact on the performance of CO2 electrolysis remains poorly understood. Here, we systematically investigate the role of the catalyst ink formulation on CO2 electrolysis using commercial CuO nanoparticles as the model pre-catalyst. We find that the presence of Nafion is essential for achieving stable product distributions due to its ability to stabilize the catalyst morphology under reaction conditions. Moreover, the Nafion content and solvent composition (water/alcohol fraction) regulate the internal structure of Nafion coatings, as well as the catalyst morphology, thereby significantly impacting CO2 electrolysis performance, resulting in variations of C2+ product Faradaic efficiency (FE) by \>3×, with C2+ FE ranging from 17 to 54% on carbon paper substrates. Using a combination of ellipsometry and in situ Raman spectroscopy during CO2 reduction, we find that such selectivity differences stem from changes to the local reaction microenvironment. In particular, the combination of high water/alcohol ratios and low Nafion fractions in the catalyst ink results in stable and favorable microenvironments, increasing the local CO2/H2O concentration ratio and promoting high CO surface coverage to facilitate C2+ production in long-term CO2 electrolysis. Therefore, this work provides insights into the critical role of Nafion binders and underlines the importance of optimizing Nafion/solvent formulations as a means of enhancing the performance of electrochemical CO2 reduction systems.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Room-temperature synthesis of lead-free copper(I)-antimony(III)-based double perovskite nanocrystals},

author = {S Wang and D Han and C Maheu and Z Xu and A Biewald and H Illner and R Hooijer and T Mayer and A Hartschuh and H Ebert and T Bein},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0144708},

doi = {10.1063/5.0144708},

year  = {2023},

date = {2023-04-05},

journal = {APL Materials},

volume = {11},

number = {4},

pages = {041110},

abstract = {In the field of perovskite solar cells, explorations of new lead-free all-inorganic perovskite materials are of great interest to address the instability and toxicity issues of lead-based hybrid perovskites. Recently, copper-antimony-based double perovskite materials have been reported with ideal band gaps, which possess great potential as absorbers for photovoltaic applications. Here, we synthesize Cs2CuSbCl6 double perovskite nanocrystals (DPNCs) at ambient conditions by a facile and fast synthesis method, namely, a modified ligand-assisted reprecipitation method. We choose methanol as a solvent for precursor salts as it is less toxic and easily removed in contrast to widely used dimethylformamide. Our computational structure search shows that the Cs2CuSbCl6 structure containing alternating [CuCl6]5− and [SbCl6]3− octahedral units is a metastable phase that is 30 meV/atom higher in energy compared to the ground state structure with [CuCl3]2− and [SbCl6]3− polyhedra. However, this metastable Cs2CuSbCl6 double perovskite structure can be stabilized through solution-based nanocrystal synthesis. Using an anion-exchange method, Cs2CuSbBr6 DPNCs are obtained for the first time, featuring a narrow bandgap of 0.9 eV. Finally, taking advantage of the solution processability of DPNCs, smooth and dense Cs2CuSbCl6 and Cs2CuSbBr6 DPNC films are successfully fabricated.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Low Temperature Optical Properties of Novel Lead-Free Cs2NaFeCl6 Perovskite Single Crystals},

author = {M Armer and P D\"{o}rflinger and A Weis and C B\"{u}chner and A Gottscholl and J H\"{o}cker and K Frank and L Nusser and M T Sirtl and B Nickel and T Bein and V Dyakonov},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adpr.202300017},

doi = {https://doi.org/10.1002/adpr.202300017},

issn = {2699-9293},

year  = {2023},

date = {2023-04-02},

journal = {Advanced Photonics Research},

volume = {n/a},

number = {n/a},

pages = {2300017},

abstract = {Lead-free double perovskites have attracted much attention as possible alternatives to lead halide based perovskites in photovoltaic applications. However, to date only few double perovskites have been successfully employed in optoelectronic device prototypes. Therefore, the search for stable and lead-free materials is ongoing. Here, we present the successful growth of high-quality Cs2NaFeCl6 single crystals and their temperature-dependent structural and optical properties. By combining electron paramagnetic resonance (EPR), crystal structure analysis and density functional theory (DFT) we could determine a cubic crystal structure with a spin of 5/2 for this material, showing strongly spin polarized character. Furthermore, combining photoluminescence (PL) and optical absorption measurements we find a bandgap of approximately 2.1 eV at room temperature as well as the presence of excitonic states. Using Elliot's formula, we are able to extract the temperature-dependent behavior of the bandgap as well as an estimated exciton binding energy of only 20 meV at 80 K.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Large-area synthesis of high electrical performance MoS2 by a commercially scalable atomic layer deposition process},

author = {N Aspiotis and K Morgan and B M\"{a}rz and K M\"{u}ller-Caspary and M Ebert and E Weatherby and M E Light and C-C Huang and D W Hewak and S Majumdar and I Zeimpekis},

url = {https://doi.org/10.1038/s41699-023-00379-z},

doi = {10.1038/s41699-023-00379-z},

issn = {2397-7132},

year  = {2023},

date = {2023-03-27},

journal = {npj 2D Materials and Applications},

volume = {7},

number = {1},

pages = {18},

abstract = {This work demonstrates a large area process for atomically thin 2D semiconductors to unlock the technological upscale required for their commercial uptake. The new atomic layer deposition (ALD) and conversion technique yields large area performance uniformity and tunability. Like graphene, 2D Transition Metal Dichalcogenides (TMDCs) are prone to upscaling challenges limiting their commercial uptake. They are challenging to grow uniformly on large substrates and to transfer on alternative substrates while they often lack in large area electrical performance uniformity. The scalable ALD process of this work enables uniform growth of 2D TMDCs on large area with independent control of layer thickness, stoichiometry and crystallinity while allowing chemical free transfers to application substrates. Field effect transistors (FETs) fabricated on flexible substrates using the process present a field effect mobility of up to 55 cm2/Vs, subthreshold slope down to 80 mV/dec and on/off ratios of 107. In addition, non-volatile memory transistors using ferroelectric FETs (FeFETs) operating at ±5 V with on/off ratio of 107 and a memory window of 3.25 V are demonstrated. These FeFETs demonstrate state-of-the-art performance with multiple state switching, suitable for one-transistor non-volatile memory and for synaptic transistors revealing the applicability of the process to flexible neuromorphic applications.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Electron Tunneling at Electrocatalytic Interfaces},

author = {M R Nouri and R M Kluge and R W Haid and J Fortmann and A Ludwig and A S Bandarenka and V Alexandrov},

url = {https://doi.org/10.1021/acs.jpcc.3c00207},

doi = {10.1021/acs.jpcc.3c00207},

issn = {1932-7447},

year  = {2023},

date = {2023-03-27},

journal = {The Journal of Physical Chemistry C},

volume = {127},

number = {13},

pages = {6321-6327},

abstract = {It was recently proposed that tunneling current fluctuations in electrochemical scanning tunneling microscopy (EC-STM) can be used to map the electrocatalytic activity of surfaces with high spatial resolution. However, the relation between the increased noise in the electron tunneling signal and the local reactivity for such complex electrode/electrolyte interfaces is only explained qualitatively or hypothetically. Herein, we employ electron transport calculations to examine tunneling at Pt surfaces under the conditions of the oxygen reduction reaction as a case study. By computing current\textendashvoltage characteristics, we reveal that the tunneling barrier strongly depends on the chemical identity of the adsorbed reaction intermediate as well as on the orientation of the average dipole moment of water species mediating electron tunneling. Our theoretical results combined with EC-STM measurements suggest that detecting reaction intermediates at electrified interfaces in operando conditions is possible based on tunneling noise amplitudes. This study also aims to stimulate further explorations of tunneling-based electron-proton transfers to enable quantum electrocatalysis beyond conventional approaches.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A re-useable microreactor for dynamic and sensitive photocatalytic measurements: Exemplified by the photoconversion of ethanol on Pt-loaded titania P25},

author = {C C Aletsee and D Hochfilzer and A Kwiatkowski and M Becherer and J Kibsgaard and I Chorkendorff and M Tschurl and U Heiz},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0134287},

doi = {10.1063/5.0134287},

year  = {2023},

date = {2023-03-23},

journal = {Review of Scientific Instruments},

volume = {94},

number = {3},

pages = {033909},

abstract = {Despite numerous advancements in synthesizing photoactive materials, the evaluation of their catalytic performance remains challenging since their fabrication often involves tedious strategies, yielding only low quantities in the μ-gram scale. In addition, these model catalysts exhibit different forms, such as powders or film(-like) structures grown on various supporting materials. Herein, we present a versatile gas phase μ-photoreactor, compatible with different catalyst morphologies, which is, in contrast to existing systems, re-openable and \textendashuseable, allowing not only post-characterization of the photocatalytic material but also enabling catalyst screening studies in short experimental time intervals. Sensitive and time-resolved reaction monitoring at ambient pressure is realized by a lid-integrated capillary, transmitting the entire gas flow from the reactor chamber to a quadrupole mass spectrometer. Due to the microfabrication of the lid from borosilicate as base material, 88% of the geometrical area can be illuminated by a light source, further enhancing sensitivity. Gas dependent flow rates through the capillary were experimentally determined to be 1015\textendash1016 molecules s−1, and in combination with a reactor volume of 10.5 μl, this results in residence times below 40 s. Furthermore, the reactor volume can easily be altered by adjusting the height of the polymeric sealing material. The successful operation of the reactor is demonstrated by selective ethanol oxidation over Pt-loaded TiO2 (P25), which serves to exemplify product analysis from dark-illumination difference spectra.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Solution-processed NiPS3 thin films from Liquid Exfoliated Inks with Long-Lived Spin-Entangled Excitons},

author = {A Shcherbakov and K Synnatschke and S Bodnar and J Zerhoch and L Eyre and F Rauh and M W Heindl and S Liu and J Konecny and I D Sharp},

url = {https://arxiv.org/abs/2303.11788},

doi = {https://doi.org/10.48550/arXiv.2303.11788},

year  = {2023},

date = {2023-03-21},

journal = {arXiv preprint arXiv:2303.11788},

abstract = {Antiferromagnets are promising materials for future opto-spintronic applications since they show spin dynamics in the THz range and no net magnetization. Recently, layered van der Waals (vdW) antiferromagnets have been reported, which combine low-dimensional excitonic properties with complex spin-structure. While various methods for the fabrication of vdW 2D crystals exist, formation of large area and continuous thin films is challenging because of either limited scalability, synthetic complexity, or low opto-spintronic quality of the final material. Here, we fabricate centimeter-scale thin films of the van der Waals 2D antiferromagnetic material NiPS3, which we prepare using a crystal ink made from liquid phase exfoliation (LPE). We perform statistical atomic force microscopy (AFM) and scanning electron microscopy (SEM) to characterize and control the lateral size and number of layers through this ink-based fabrication. Using ultrafast optical spectroscopy at cryogenic temperatures, we resolve the dynamics of photoexcited excitons. We find antiferromagnetic spin arrangement and spin-entangled Zhang-Rice multiplet excitons with lifetimes in the nanosecond range, as well as ultranarrow emission linewidths, despite the disordered nature of our films. Thus, our findings demonstrate scalable thin-film fabrication of high-quality NiPS3, which is crucial for translating this 2D antiferromagnetic material into spintronic and nanoscale memory devices and further exploring its complex spin-light coupled states.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Interpreting Ultrafast Electron Transfer on Surfaces with a Converged First-Principles Newns-Anderson Chemisorption Function},

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

url = {https://arxiv.org/abs/2303.11412},

doi = {https://doi.org/10.48550/arXiv.2303.11412},

year  = {2023},

date = {2023-03-20},

journal = {arXiv preprint arXiv:2303.11412},

abstract = {We study the electronic coupling between an adsorbate and a metal surface by calculating tunneling matrix elements Had directly from first principles. For this we employ a projection of the Kohn-Sham Hamiltonian upon a diabatic basis using a version of the popular Projection-Operator Diabatization approach. An appropriate integration of couplings over the Brillouin zone allows the first calculation of a size-convergent Newns-Anderson chemisorption function, a coupling-weighted density of states measuring the line broadening of an adsorbate frontier state upon adsorption. This broadening corresponds to the experimentally-observed lifetime of an electron in the state, which we confirm for core-excited Ar∗(2p−13/24s) atoms on a number of transition metal (TM) surfaces. Yet, beyond just lifetimes, the chemisorption function is highly interpretable and encodes rich information on orbital phase interactions on the surface. The model thus captures and elucidates key aspects of the electron transfer process. Finally, a decomposition into angular momentum components reveals the hitherto unresolved role of the hybridized d-character of the TM surface in the resonant electron transfer, and elucidates the coupling of the adsorbate to the surface bands over the entire energy scale.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Revealing Surface and Interface Evolution of Molybdenum Nitride as Carrier-Selective Contacts for Crystalline Silicon Solar Cells},

author = {Y Li and Y Li and J E Heger and J Zhou and T Guan and C R Everett and W Wei and Z Hong and Y Wu and X Jiang and S Yin and X Yang and D Li and C Jiang and B Sun and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1021/acsami.2c22781},

doi = {10.1021/acsami.2c22781},

issn = {1944-8244},

year  = {2023},

date = {2023-03-06},

journal = {ACS Applied Materials \& Interfaces},

volume = {15},

number = {10},

pages = {13753-13760},

abstract = {Molybdenum nitride (MoNx) was perceived as carrier-selective contacts (CSCs) for crystalline silicon (c-Si) solar cells due to having proper work functions and excellent conductivities. However, the poor passivation and non-Ohmic contact at the c-Si/MoNx interface endow an inferior hole selectivity. Here, the surface, interface, and bulk structures of MoNx films are systematically investigated by X-ray scattering, surface spectroscopy, and electron microscope analysis to reveal the carrier-selective features. Surface layers with the composition of MoO2.51N0.21 form upon air exposure, which induces the overestimated work function and explains the origin of inferior hole selectivities. The c-Si/MoNx interface is confirmed to adopt long-term stability, providing guidance for designing stable CSCs. A detailed evolution of the scattering length density, domain sizes, and crystallinity in the bulk phase is presented to elucidate its superior conductivity. These multiscale structural investigations offer a clear structure\textendashfunction correlation of MoNx films, providing key inspiration for developing excellent CSCs for c-Si solar cells.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Anharmonic Fluctuations Govern the Band Gap of Halide Perovskites},

author = {S A Seidl and X Zhu and G Reuveni and S Aharon and C Gehrmann and S Caicedo-D\'{a}vila and O Yaffe and D A Egger},

url = {https://arxiv.org/abs/2303.01603},

doi = {https://doi.org/10.48550/arXiv.2303.01603},

year  = {2023},

date = {2023-03-02},

journal = {arXiv preprint arXiv:2303.01603},

abstract = {We determine the impact of anharmonic thermal vibrations on the fundamental band gap of CsPbBr3, a prototypical model system for the broader class of halide perovskite semiconductors. Through first-principles molecular dynamics and stochastic calculations, we find that anharmonic fluctuations are a key effect in the electronic structure of these materials. We present experimental and theoretical evidence that important characteristics, such as a mildly changing band-gap value across a temperature range that includes phase-transitions, cannot be explained by harmonic phonons thermally perturbing an average crystal structure and symmetry. Instead, the thermal characteristics of the electronic structure are microscopically connected to anharmonic vibrational contributions to the band gap that reach a fairly large magnitude of 450 meV at 425 K.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Correlative analysis on InGaN/GaN nanowires: structural and optical properties of self-assembled short-period superlattices},

author = {M Alonso-Orts and R H\"{o}tzel and T Grieb and M Auf Der Maur and M Ries and F Nippert and B M\"{a}rz and K M\"{u}ller-Caspary and M R Wagner and A Rosenauer and M Eickhoff},

url = {https://doi.org/10.1186/s11671-023-03808-6},

doi = {10.1186/s11671-023-03808-6},

issn = {2731-9229},

year  = {2023},

date = {2023-03-01},

journal = {Discover Nano},

volume = {18},

number = {1},

pages = {27},

abstract = {The influence of self-assembled short-period superlattices (SPSLs) on the structural and optical properties of InGaN/GaN nanowires (NWs) grown by PAMBE on Si (111) was investigated by STEM, EDXS, µ-PL analysis and k·p simulations. STEM analysis on single NWs indicates that in most of the studied nanostructures, SPSLs self-assemble during growth. The SPSLs display short-range ordering of In-rich and In-poor InxGa1-xN regions with a period of 2\textendash3 nm that are covered by a GaN shell and that transition to a more homogenous InxGa1-xN core. Polarization- and temperature-resolved PL analysis performed on the same NWs shows that they exhibit a strong parallel polarized red-yellow emission and a predominantly perpendicular polarized blue emission, which are ascribed to different In-rich regions in the nanostructures. The correlation between STEM, µ-PL and k·p simulations provides better understanding of the rich optical emission of complex III-N nanostructures and how they are impacted by structural properties, yielding the significant impact of strain on self-assembly and spectral emission.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Selective anode catalyst for the mitigation of start-up/shut-down induced cathode degradation in proton exchange membrane fuel cells},

author = {B M St\"{u}hmeier and A M Damjanovi\'{c} and K Rodewald and H A Gasteiger},

url = {https://www.sciencedirect.com/science/article/pii/S037877532201549X},

doi = {https://doi.org/10.1016/j.jpowsour.2022.232572},

issn = {0378-7753},

year  = {2023},

date = {2023-02-28},

journal = {Journal of Power Sources},

volume = {558},

pages = {232572},

abstract = {Reducing cathode degradation during start-up and shut-down (SUSD) events is one of the remaining challenges for the widespread application of proton exchange membrane fuel cells (PEMFC). An anode catalyst that is selective for the hydrogen oxidation reaction (HOR) while its activity for the oxygen reduction reaction (ORR) is severely reduced, could substantially prolong the SUSD lifetime of the cathode. Herein, we report on single-cell measurements with a Pt/TiOx/C (x ≤ 2) catalyst that has been shown to be HOR selective by rotating disk electrode (RDE) measurements. The HOR activity of the catalyst was compared to conventional Pt/C by H2-pump measurements at ultra-low loadings. The ORR activity of Pt/TiOx/C was compared to Pt/C anodes with high and low Pt loadings, showing a diminished selectivity in MEA compared to RDE measurements. Unfortunately, the PEMFC performance with the Pt/TiOx/C catalyst was compromised by TiOx dissolution, deduced from voltage loss analysis of the H2/O2 performance curves and by ex-situ SEM/EDX of the MEAs. Finally, the successful mitigation of cathode carbon corrosion was shown over the course of 3200 SUSD cycles, whereby the retention of Pt surface area when using a Pt/TiOx/C anode by far exceeded the improvements expected from the reduced ORR kinetics.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Systematic Errors of Electric Field Measurements in Ferroelectrics by Unit Cell Averaged Momentum Transfers in STEM},

author = {A Strauch and B M\"{a}rz and T Denneulin and M Cattaneo and A Rosenauer and K M\"{u}ller-Caspary},

url = {https://doi.org/10.1093/micmic/ozad016},

doi = {10.1093/micmic/ozad016},

issn = {1431-9276},

year  = {2023},

date = {2023-02-23},

journal = {Microscopy and Microanalysis},

volume = {29},

number = {2},

pages = {499-511},

abstract = {When using the unit cell average of first moment data from four-dimensional scanning transmission electron microscopy (4D-STEM) to characterize ferroelectric materials, a variety of sources of systematic errors needs to be taken into account. In particular, these are the magnitude of the acceleration voltage, STEM probe semi-convergence angle, sample thickness, and sample tilt out of zone axis. Simulations show that a systematic error of calculated electric fields using the unit cell averaged momentum transfer originates from violation of point symmetry within the unit cells. Thus, values can easily exceed those of potential polarization-induced electric fields in ferroelectrics. Importantly, this systematic error produces deflection gradients between different domains seemingly representing measured fields. However, it could be shown that for PbZr0.2Ti0.8O3, many adjacent domains exhibit a relative crystallographic mistilt and in-plane rotation. The experimental results show that the method gives qualitative domain contrast. Comparison of the calculated electric field with the systematic error showed that the domain contrast of the unit cell averaged electric fields is mainly caused by dynamical scattering effects and the electric field plays only a minor role, if present at all.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Comprehensive Investigation of Anion Species in Crystalline Li+ ion Conductor Li27−x[P4O7+xN9−x]O3 (x≈1.9(3))},

author = {S Schneider and E-M Wendinger and V Baran and A-K Hatz and B V Lotsch and M Nentwig and O Oeckler and T Br\"{a}uniger and W Schnick},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202300174},

doi = {https://doi.org/10.1002/chem.202300174},

issn = {0947-6539},

year  = {2023},

date = {2023-02-21},

journal = {Chemistry \textendash A European Journal},

volume = {29},

number = {27},

pages = {e202300174},

abstract = {Abstract The Li+ ion conductor Li27−x[P4O7+xN9−x]O3 (x≈1.9) has been synthesized from P3N5, Li3N and Li2O in a Ta ampoule at 800 °C under Ar atmosphere. The cubic compound crystallizes in space group with a=12.0106(14) r{A} and Z=4. It contains both non-condensed [PO2N2]5− and [PO3N]4− tetrahedra as well as O2− ions, surrounded by Li+ ions. Charge neutrality is achieved by partial occupancy of Li positions, which was refined with neutron powder diffraction data. Measurements of the partial ionic and electronic conductivity show a total ionic conductivity of 6.6×10−8 S cm−1 with an activation energy of 0.46±0.02 eV and a bulk ionic conductivity of 4×10−6 S cm−1 at 25 °C, which is close to the ionic conductivity of amorphous lithium nitridophosphate. This makes Li27−x[P4O7+xN9−x]O3 an interesting candidate for investigation of structural factors affecting ionic conductivity in lithium oxonitridophosphates.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Shedding Light on the Moisture Stability of Halide Perovskite Thin Films},

author = {K Sun and P M\"{u}ller-Buschbaum},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ente.202201475},

doi = {https://doi.org/10.1002/ente.202201475},

issn = {2194-4288},

year  = {2023},

date = {2023-02-08},

journal = {Energy Technology},

volume = {n/a},

number = {n/a},

pages = {2201475},

abstract = {To date, remarkable progress has been achieved in the power conversion efficiency of perovskite solar cells (PSCs). Nevertheless, the instability and degradation of PSCs under external stimuli still shadow the prospectus of their commercialization. As a notorious culprit deteriorating the stability of PSCs, moisture-induced degradation is thereby an important aspect. Herein, a comprehensive review of moisture effects on the halide perovskite film, in particular the moisture-induced degradation mechanism and methods toward enhancing the stability, is discussed. In detail, the benefits for perovskite films having a certain amount of water incorporation are elucidated, and the underlying moisture-induced structural degradation and decomposition process of perovskites are summarized. Light is also shed on the methods to enhance the moisture stability of perovskites, particularly a 3D/2D heterostructure. Thereby, this review will enlighten the readers of understanding moisture-induced degradation and the development of stable perovskites.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Solvent Modulation of Chiral Perovskite Films Enables High Circularly Polarized Luminescence Performance from Chiral Perovskite/Quantum Dot Composites},

author = {H Zhu and Q Wang and K Sun and W Chen and J Tang and J Hao and Z Wang and J Sun and W C H Choy and P M\"{u}ller-Buschbaum and X W Sun and D Wu and K Wang},

url = {https://doi.org/10.1021/acsami.2c20716},

doi = {10.1021/acsami.2c20716},

issn = {1944-8244},

year  = {2023},

date = {2023-02-08},

journal = {ACS Applied Materials \& Interfaces},

volume = {15},

number = {7},

pages = {9978-9986},

abstract = {Materials with circularly polarized luminescence (CPL) activity are promising in many chiroptoelectronics fields, such as for biological probes, asymmetric photosynthesis, information storage, spintronic devices, and so on. Promoting the value of the dissymmetry factor (glum) for the CPL-active materials based on chiral perovskite draws increasing attention since a higher glum value indicates better CPL. In this work, we find that, after being treated with a facile solvent modulation strategy, the chirality of 2D chiral perovskite films has been enhanced a lot, which we attribute to an increased lattice distortion degree. By forming chiral perovskite/quantum dot (QD) composites, the CPL-active material is successfully obtained. The calculated maximum |glum| of these composites increased over 4 times after solvent modulation treatment (1.53 × 10\textendash3 for the pristine sample of R-DMF and 6.91 × 10\textendash3 for R-NMP) at room temperature. Moreover, the enhancement of the CPL intensity is ascribed to two aspects: one is the generation and transportation of spin-polarized charge carriers from chiral perovskite films to combine in the QD layer, and the other is the solvent modulation strategy to enlarge the lattice distortion of chiral perovskite films. This facile route provides an effective way to construct CPL-active materials. More importantly, this kind of composite material (chiral perovskite film/QD layer) can be easily applied for fabricating circularly polarized light-emitting diode devices for electroluminescence.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Direct Linearly-Polarised Electroluminescence from Perovskite Nanoplatelet Superlattices},

author = {J Ye and A Ren and L Dai and T Baikie and R Guo and D Pal and S Gorgon and J E Heger and J Huang and Y Sun},

url = {https://arxiv.org/abs/2302.03582},

doi = {https://doi.org/10.48550/arXiv.2302.0358},

year  = {2023},

date = {2023-02-07},

journal = {arXiv preprint arXiv:2302.03582},

abstract = {Polarised light is critical for a wide range of applications, but is usually generated by filtering unpolarised light, which leads to significant energy losses and requires additional optics. Herein, the direct emission of linearly-polarised light is achieved from light-emitting diodes (LEDs) made of CsPbI3 perovskite nanoplatelet superlattices. Through use of solvents with different vapour pressures, the self-assembly of perovskite nanoplatelets is achieved to enable fine control over the orientation (either face-up or edge-up) and therefore the transition dipole moment. As a result of the highly-uniform alignment of the nanoplatelets, as well as their strong quantum and dielectric confinement, large exciton fine-structure splitting is achieved at the film level, leading to pure-red LEDs exhibiting a high degree of linear polarisation of 74.4% without any photonic structures. This work unveils the possibilities of perovskite nanoplatelets as a highly promising source of linearly-polarised electroluminescence, opening up the development of next-generation 3D displays and optical communications from this highly versatile, solution-processable system.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Mechanisms of Degradation of Na2Ni[Fe(CN)6] Functional Electrodes in Aqueous Media: A Combined Theoretical and Experimental Study},

author = {X Lamprecht and I Evazzade and I Ungerer and L Hromadko and J M Macak and A S Bandarenka and V Alexandrov},

url = {https://doi.org/10.1021/acs.jpcc.2c08222},

doi = {10.1021/acs.jpcc.2c08222},

issn = {1932-7447},

year  = {2023},

date = {2023-01-30},

journal = {The Journal of Physical Chemistry C},

volume = {127},

number = {5},

pages = {2204-2214},

abstract = {Prussian blue analogues (PBAs) are versatile functional materials with numerous applications ranging from electrocatalysis and batteries to sensors and electrochromic devices. Their electrochemical performance involving long-term cycling stability strongly depends on the electrolyte composition. In this work, we use density functional theory calculations and experiments to elucidate the mechanisms of degradation of model Na2Ni[Fe(CN)6] functional electrodes in aqueous electrolytes. Next to the solution pH and cation concentration, we identify anion adsorption as a major driving force for electrode dissolution. Notably, the nature of adsorbed anions can control the mass and charge transfer mechanisms during metal cation intercalation as well as the electrode degradation rate. We find that weakly adsorbing anions, such as NO3\textendash, impede the degradation, while strongly adsorbing anions, such as SO42\textendash, accelerate it. The results of this study provide practical guidelines for electrolyte optimization and can likely be extrapolated to the whole family of PBAs operating in aqueous media.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ligand Chemistry of Inorganic Lead Halide Perovskite Nanocrystals},

author = {N Fiuza-Maneiro and K Sun and I L\'{o}pez-Fern\'{a}ndez and S G\'{o}mez-Gra\~{n}a and P M\"{u}ller-Buschbaum and L Polavarapu},

url = {https://doi.org/10.1021/acsenergylett.2c02363},

doi = {10.1021/acsenergylett.2c02363},

year  = {2023},

date = {2023-01-26},

journal = {ACS Energy Letters},

pages = {1152-1191},

abstract = {Lead halide perovskite nanocrystals (LHP NCs) have emerged as next-generation semiconductor materials with outstanding optical and optoelectronic properties. Because of the high surface-to-volume ratio, the optical and optoelectronic performance and the colloidal stability of LHP NCs largely depend on their surface chemistry, especially the ligands and surface termination. On one hand, the capping ligands improve the colloidal stability and luminescence; on the other hand the highly dynamic binding nature of ligands is detrimental to the colloidal stability and photoluminescence of LHP NCs. In addition, the surface functionalization with desired molecules induces new functionalities such as chirality, light harvesting, and triplet sensitization through energy/electron transfer or use as X-ray detectors. In this review, we present the current understanding of an atomic view of the surface chemistry of colloidal LHP NCs, including crystal termination, vacancies, and different types of capping ligands. Furthermore, we discuss the ligand-induced functionalities, including photocatalysis and chirality.},

keywords = {Foundry Inorganic, Foundry Organic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Superlattice deformation in quantum dot films on flexible substrates via uniaxial strain},

author = {J E Heger and W Chen and H Zhong and T Xiao and C Harder and F C Apfelbeck and A F Weinzierl and R Boldt and L Schraa and E Euchler and A K Sambale and K Schneider and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {http://dx.doi.org/10.1039/D2NH00548D},

doi = {10.1039/D2NH00548D},

issn = {2055-6756},

year  = {2023},

date = {2023-01-23},

journal = {Nanoscale Horizons},

volume = {8},

number = {3},

pages = {383-395},

abstract = {The superlattice in a quantum dot (QD) film on a flexible substrate deformed by uniaxial strain shows a phase transition in unit cell symmetry. With increasing uniaxial strain, the QD superlattice unit cell changes from tetragonal to cubic to tetragonal phase as measured with in situ grazing-incidence small-angle X-ray scattering (GISAXS). The respective changes in the optoelectronic coupling are probed with photoluminescence (PL) measurements. The PL emission intensity follows the phase transition due to the resulting changing inter-dot distances. The changes in PL intensity accompany a redshift in the emission spectrum, which agrees with the F\"{o}rster resonance energy transfer (FRET) theory. The results are essential for a fundamental understanding of the impact of strain on the performance of flexible devices based on QD films, such as wearable electronics and next-generation solar cells on flexible substrates.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Rapid Data-Efficient Optimization of Perovskite Nanocrystal Syntheses through Machine Learning Algorithm Fusion},

author = {C Lampe and I Kouroudis and M Harth and S Martin and A Gagliardi and A S Urban},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202208772},

doi = {https://doi.org/10.1002/adma.202208772},

issn = {0935-9648},

year  = {2023},

date = {2023-01-21},

journal = {Advanced Materials},

volume = {n/a},

number = {n/a},

pages = {2208772},

abstract = {Abstract With the demand for renewable energy and efficient devices rapidly increasing, a need arises to find and optimize novel (nano)materials. With sheer limitless possibilities for material combinations and synthetic procedures, obtaining novel, highly functional materials has been a tedious trial and error process. Recently, machine learning has emerged as a powerful tool to help optimize syntheses; however, most approaches require a substantial amount of input data, limiting their pertinence. Here, we merge three well-known machine-learning models with Bayesian Optimization into one to optimize the synthesis of CsPbBr3 nanoplatelets with limited data demand. The algorithm can accurately predict the photoluminescence emission maxima of nanoplatelet dispersions using only the three precursor ratios as input parameters. This allowed us to fabricate previously unobtainable 7 and 8 monolayer-thick nanoplatelets. Moreover, the algorithm dramatically improved the homogeneity of 2-6 monolayer-thick nanoplatelet dispersions, as evidenced by narrower and more symmetric photoluminescence spectra. Decisively, only 200 total syntheses were required to achieve this vast improvement, highlighting how rapidly material properties can be optimized. The algorithm is highly versatile and can incorporate additional synthetic parameters. Accordingly, it is readily applicable to other less-explored nanocrystal syntheses and can help rapidly identify and improve exciting compositions' quality. This article is protected by copyright. All rights reserved},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Lead-free, luminescent perovskite nanocrystals obtained through ambient condition synthesis},

author = {F Treber and K Frank and B Nickel and C Lampe and A S Urban},

url = {https://arxiv.org/abs/2301.08936},

doi = {https://doi.org/10.48550/arXiv.2301.08936},

year  = {2023},

date = {2023-01-21},

journal = {arXiv preprint arXiv:2301.08936},

abstract = {Heterovalent substitution of toxic lead is an increasingly popular design strategy to obtain environmentally sustainable variants of the exciting material class of halide perovskites. Perovskite nanocrystals (NCs) obtained through solution-based methods exhibit exceedingly high optical quality. Unfortunately, most of these synthesis routes still require reaction under inert gas and at very high temperatures. Herein we present a novel synthesis routine for lead-free double perovskite NCs. We combine hot injection and ligand-assisted reprecipitation (LARP) methods to achieve a low-temperature and ambient atmosphere-based synthesis for manganese-doped Cs_2NaBiCl_6 NCs. Mn incorporation is critical for the otherwise non-emissive material, with a 9:1 Bi:Mn precursor ratio maximizing the bright orange photoluminescence (PL) and quantum yield (QY). Higher temperatures slightly increased the material's performance, yet NCs synthesized at room temperature were still emissive, highlighting the versatility of the synthetic approach. Furthermore, the NCs show excellent long-term stability in ambient conditions, facilitating additional investigations and energy-related applications.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {All-optical controlled-NOT logic gate achieving directional asymmetric transmission based on metasurface doublet},

author = {Y Huang and T Xiao and S Chen and Z Xie and J Zheng and J Zhu and Y Su and W Chen and K Liu and M Tang and P M\"{u}ller-Buschbaum and L Li},

url = {http://www.oejournal.org//article/doi/10.29026/oea.2023.220073},

doi = {10.29026/oea.2023.220073},

issn = {2096-4579},

year  = {2023},

date = {2023-01-18},

journal = {Opto-Electronic Advances},

pages = {220073-1-220073-9},

abstract = {Optical logic gates play important roles in all-optical logic circuits, which lie at the heart of the next-generation optical computing technology. However, the intrinsic contradiction between compactness and robustness hinders the development in this field. Here, we propose a simple design principle that can possess multiple-input-output states according to the incident circular polarization and direction based on the metasurface doublet, which enables controlled-NOT logic gates in infrared region. Therefore, the directional asymmetric electromagnetic transmission can be achieved. As a proof of concept, a spin-dependent Janus metasurface is designed and experimentally verified that four distinct images corresponding to four input states can be captured in the far-field. In addition, since the design method is derived from geometric optics, it can be easily applied to other spectra. We believe that the proposed metasurface doublet may empower many potential applications in chiral imaging, chiroptical spectroscopy and optical computing.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Surface Oxygen Depletion of Layered Transition Metal Oxides in Li-Ion Batteries Studied by Operando Ambient Pressure X-ray Photoelectron Spectroscopy},

author = {A T S Freiberg and S Qian and J Wandt and H A Gasteiger and E J Crumlin},

url = {https://doi.org/10.1021/acsami.2c19008},

doi = {10.1021/acsami.2c19008},

issn = {1944-8244},

year  = {2023},

date = {2023-01-09},

journal = {ACS Applied Materials \& Interfaces},

volume = {15},

number = {3},

pages = {4743-4754},

abstract = {A new operando spectro-electrochemical setup was developed to study oxygen depletion from the surface of layered transition metal oxide particles at high degrees of delithiation. An NCM111 working electrode was paired with a chemically delithiated LiFePO4 counter electrode in a fuel cell-inspired membrane electrode assembly (MEA). A propylene carbonate-soaked Li-ion conducting ionomer served as an electrolyte, providing both good electrochemical performance and direct probing of the NCM111 particles during cycling by ambient pressure X-ray photoelectron spectroscopy. The irreversible emergence of an oxygen-depleted phase in the O 1s spectra of the layered oxide particles was observed upon the first delithiation to high state-of-charge, which is in excellent agreement with oxygen release analysis via mass spectrometry analysis of such MEAs. By comparing the metal oxide-based O 1s spectral features to the Ni 2p3/2 intensity, we can calculate the transition metal-to-oxygen ratio of the metal oxide close to the particle surface, which shows good agreement with the formation of a spinel-like stoichiometry as an oxygen-depleted phase. This new setup enables a deeper understanding of interfacial changes of layered oxide-based cathode active materials for Li-ion batteries upon cycling.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Morphology Matters: 0D/2D WO3 Nanoparticle-Ruthenium Oxide Nanosheet Composites for Enhanced Photocatalytic Oxygen Evolution Reaction Rates},

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

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202203315},

doi = {https://doi.org/10.1002/aenm.202203315},

issn = {1614-6832},

year  = {2022},

date = {2022-12-22},

journal = {Advanced Energy Materials},

volume = {n/a},

number = {n/a},

pages = {2203315},

abstract = {Abstract In the field of artificial photosynthesis with semiconductor light harvesters, the default cocatalyst morphologies are isotropic, 0D nanoparticles. Herein, the use of highly anisotropic 2D ruthenium oxide nanosheet (RONS) cocatalysts as an approach to enhance photocatalytic oxygen evolution (OER) rates on commercial WO3 nanoparticles (0D light harvester) is presented. At optimal cocatalyst loadings and identical photocatalysis conditions, WO3 impregnated with RONS (RONS/WO3) shows a fivefold increase in normalized photonic efficiency compared to when it is impregnated with conventional ruthenium oxide (rutile) nanoparticles (RONP/WO3). The superior RONS/WO3 performance is attributed to two special properties of the RONS: i) lower electrochemical water oxidation overpotential for RONS featuring highly active edge sites, and ii) decreased parasitic light absorption on RONS. Evidence is presented that OER photocatalytic performance can be doubled with control of RONS edges and it is shown that compared to WO3 impregnated with RONP, the advantageous optical properties and geometry of RONS decrease the fraction of light absorbed by the cocatalyst, thus reducing the parasitic light absorption on the RONS/WO3 composite. Therefore, the results presented in the current study are expected to promote engineering of cocatalyst morphology as a complementary concept to optimize light harvester-cocatalyst composites for enhanced photocatalytic efficiency.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Combining impedance and hydrodynamic methods in electrocatalysis. Characterization of Pt(pc), Pt5Gd, and nanostructured Pd for the hydrogen evolution reaction},

author = {K-T Song and C M Schott and P M Schneider and S A Watzele and R M Kluge and E L Gubanova and A S Bandarenka},

url = {http://iopscience.iop.org/article/10.1088/2515-7655/acabe5},

issn = {2515-7655},

year  = {2022},

date = {2022-12-15},

journal = {Journal of Physics: Energy},

abstract = {Electrochemical hydrodynamic techniques typically involve electrodes that move relative to the solution. Historically, approaches involving rotating disc electrode (RDE) configurations have become very popular, as one can easily control the electroactive species' mass transport in those cases. The combination of cyclic voltammetry and RDE is nowadays one of the standard characterization protocols in electrocatalysis. On the other hand, impedance spectroscopy is one of the most informative electrochemistry techniques, enabling the acquisition of information on the processes taking place simultaneously at the electrode/electrolyte interface. In this work, we investigated the hydrogen evolution reaction (HER) catalyzed by polycrystalline Pt (Pt(pc)) and Pt5Gd disc electrodes and characterized them using RDE and EIS techniques simultaneously. Pt5Gd shows higher HER activities than Pt in acidic and alkaline media due to strain and ligand effects. The mechanistic study of the reaction showed that the rotation rates in acidic media have no effect on the contribution of the Volmer-Heyrovsky and Volmer-Tafel pathways. However, the Volmer-Heyrovsky pathway dominates at lower rotation rates in alkaline media. Besides, the HER in acidic solutions depends more strongly on mass diffusion than in alkaline media. In addition to simple and clearly defined systems, the combined method of both techniques is applicable for systems with greater complexity, such as Pd/C nanostructured catalysts. Applying the above-presented approach, we found that the Volmer-Tafel pathway is the dominating mechanism of the HER for this catalytic system.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Real-Time Investigation of Sulfur Vacancy Generation and Passivation in Monolayer Molybdenum Disulfide via in situ X-ray Photoelectron Spectromicroscopy},

author = {T Gr\"{u}nleitner and A Henning and M Bissolo and M Zengerle and L Gregoratti and M Amati and P Zeller and J Eichhorn and A V Stier and A W Holleitner and J J Finley and I D Sharp},

url = {https://doi.org/10.1021/acsnano.2c06317},

doi = {10.1021/acsnano.2c06317},

issn = {1936-0851},

year  = {2022},

date = {2022-12-14},

journal = {ACS Nano},

abstract = {Understanding the chemical and electronic properties of point defects in two-dimensional materials, as well as their generation and passivation, is essential for the development of functional systems, spanning from next-generation optoelectronic devices to advanced catalysis. Here, we use synchrotron-based X-ray photoelectron spectroscopy (XPS) with submicron spatial resolution to create sulfur vacancies (SVs) in monolayer MoS2 and monitor their chemical and electronic properties in situ during the defect creation process. X-ray irradiation leads to the emergence of a distinct Mo 3d spectral feature associated with undercoordinated Mo atoms. Real-time analysis of the evolution of this feature, along with the decrease of S content, reveals predominant monosulfur vacancy generation at low doses and preferential disulfur vacancy generation at high doses. Formation of these defects leads to a shift of the Fermi level toward the valence band (VB) edge, introduction of electronic states within the VB, and formation of lateral pn junctions. These findings are consistent with theoretical predictions that SVs serve as deep acceptors and are not responsible for the ubiquitous n-type conductivity of MoS2. In addition, we find that these defects are metastable upon short-term exposure to ambient air. By contrast, in situ oxygen exposure during XPS measurements enables passivation of SVs, resulting in partial elimination of undercoordinated Mo sites and reduction of SV-related states near the VB edge. Correlative Raman spectroscopy and photoluminescence measurements confirm our findings of localized SV generation and passivation, thereby demonstrating the connection between chemical, structural, and optoelectronic properties of SVs in MoS2.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Heterovalent Tin Alloying in Layered MA3Sb2I9 Thin Films: Assessing the Origin of Enhanced Absorption and Self-Stabilizing Charge States},

author = {A Weis and P Ganswindt and W Kaiser and H Illner and C Maheu and N Gl\"{u}ck and P D\"{o}rflinger and M Armer and V Dyakonov and J P Hofmann and E Mosconi and F De Angelis and T Bein},

url = {https://doi.org/10.1021/acs.jpcc.2c06106},

doi = {10.1021/acs.jpcc.2c06106},

issn = {1932-7447},

year  = {2022},

date = {2022-11-30},

journal = {The Journal of Physical Chemistry C},

volume = {126},

number = {49},

pages = {21040-21049},

abstract = {Heteroatom alloying of lead-free perovskite derivatives is a highly promising route to tailor their optoelectronic properties and stability for multiple applications. Here, we demonstrate the facile solution-based synthesis of Sn-alloyed layered MA3Sb2I9 thin films by precursor engineering, combining acetate and halide salts. An increasing concentration of tin halides in different oxidation states leads to a strong boost in absorption over the whole visible spectrum. We demonstrate phase-pure synthesis and elucidate the heterovalent incorporation of Sn into the MA3Sb2I9 lattice, proving the formation of additional electronic states in the bandgap by theoretical calculations. On this basis, we dissect the strong absorption increase into three components that we attribute to intervalence and heteroatom-induced interband absorption. Finally, we show the charge-stabilizing effect of the system through robustness toward precursors in mixed oxidation states and trace the improved ambient stability of this material back to this feature.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Tailored fabrication of quasi-isoporous and double layered α-Fe2O3 thin films and their application in photovoltaic devices},

author = {S Yin and Y Zou and M A Reus and X Jiang and S Tu and T Tian and R Qi and Z Xu and S Liang and Y Cheng and J E Heger and M Schwartzkopf and S V Roth and P M\"{u}ller-Buschbaum},

url = {https://www.sciencedirect.com/science/article/pii/S1385894722056157},

doi = {https://doi.org/10.1016/j.cej.2022.140135},

issn = {1385-8947},

year  = {2022},

date = {2022-11-21},

journal = {Chemical Engineering Journal},

pages = {140135},

abstract = {A series of α-Fe2O3 thin films with distinct morphologies are prepared via a facile polystyrene-block-polyethylene oxide templated sol\textendashgel method. By tailoring the poor solvent contents and FeCl3-to-polymer weight ratio in the sol\textendashgel solutions, quasi-isoporous α-Fe2O3 thin films with different substructures and thicknesses are obtained. Via a thermal annealing post-treatment, double layered structures are induced by a synergistic dewetting and Oswald ripening effect. Special focus is set on the α-Fe2O3 thin films prepared with no annealing/annealing-medium FeCl3 concentration, as they possess uniform periodic structures, which is suitable to be used as hole blocking modification layer of perovskite solar cells (PSCs). An improved power conversion efficiency (PCE) is obtained when the double layered α-Fe2O3 thin film is applied as the hole blocking modification layer for PSCs. The improved PCE primarily originates from the increased VOC, which probably benefits from the synergistic effect of the suppressed charge carrier recombination at the interfaces, the enhanced light transmittance as well as the superior electron extraction capacity.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Direct Coupling of Methane and Carbon Dioxide on Tantalum Cluster Cations},

author = {J Lengyel and N Levin and M On\v{c}\'{a}k and K Jakob and M Tschurl and U Heiz},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202203259},

doi = {https://doi.org/10.1002/chem.202203259},

issn = {0947-6539},

year  = {2022},

date = {2022-11-20},

journal = {Chemistry \textendash A European Journal},

volume = {n/a},

number = {n/a},

abstract = {Understanding molecular-scale reaction mechanisms is crucial for the design of modern catalysts with industrial prospect. Through joint experimental and computational studies, we investigate the direct coupling reaction of CH4 and CO2, two abundant greenhouse gases, mediated by Ta1,4+ ions to form larger oxygenated hydrocarbons. Coherent with proposed elementary steps, we expose products of CH4 dehydrogenation [Ta1,4CH2]+ to CO2 in a ring electrode ion trap. Product analysis and reaction kinetics indicate a predisposition of the tetramers for C\textendashO coupling with a conversion to products of CH2O, whereas atomic cations enable C\textendashC coupling yielding CH2CO. Many of the experimental findings are supported by thermodynamic computations, connecting structure, electronic properties, and catalyst function. Moreover, the study of bare Ta1,4+ compounds indicates that methane dehydrogenation is a significant initial step in the direct coupling reaction, enabling new, yet unknown reaction pathways.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {High-Performance Monolayer MoS2 Field-Effect Transistors on Cyclic Olefin Copolymer-Passivated SiO2 Gate Dielectric},

author = {S B Kalkan and E Najafidehaghani and Z Gan and J Drewniok and M F Lichtenegger and U H\"{u}bner and A S Urban and A George and A Turchanin and B Nickel},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202201653},

doi = {https://doi.org/10.1002/adom.202201653},

issn = {2195-1071},

year  = {2022},

date = {2022-11-18},

journal = {Advanced Optical Materials},

volume = {n/a},

number = {n/a},

pages = {2201653},

abstract = {Abstract Trap states of the semiconductor/gate dielectric interface give rise to a pronounced subthreshold behavior in field-effect transistors (FETs) diminishing and masking intrinsic properties of 2D materials. To reduce the well-known detrimental effect of SiO2 surface traps, this work spin-coated an ultrathin (≈5 nm) cyclic olefin copolymer (COC) layer onto the oxide and this hydrophobic layer acts as a surface passivator. The chemical resistance of COC allows to fabricate monolayer MoS2 FETs on SiO2 by standard cleanroom processes. This way, the interface trap density is lowered and stabilized almost fivefold, to around 5 × 1011 cm−2 eV−1, which enables low-voltage FETs even on 300 nm thick SiO2. In addition to this superior electrical performance, the photoresponsivity of the MoS2 devices on passivated oxide is also enhanced by four orders of magnitude compared to nonpassivated MoS2 FETs. Under these conditions, negative photoconductivity and a photoresponsivity of 3 × 107 A W−1 is observed which is a new highest value for MoS2. These findings indicate that the ultrathin COC passivation of the gate dielectric enables to probe exciting properties of the atomically thin 2D semiconductor, rather than interface trap dominated effects.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Structure Determination of the Crystalline LiPON Model Structure Li5+xP2O6−xN1+x with x≈0.9},

author = {S Schneider and L G Balzat and B V Lotsch and W Schnick},

url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202202984},

doi = {https://doi.org/10.1002/chem.202202984},

issn = {0947-6539},

year  = {2022},

date = {2022-11-16},

journal = {Chemistry \textendash A European Journal},

volume = {29},

number = {9},

pages = {e202202984},

abstract = {Abstract Non-crystalline lithium oxonitridophosphate (LiPON) is used as solid electrolyte in all-solid-state batteries. Crystalline lithium oxonitridophosphates are important model structures to retrieve analytical information that can be used to understand amorphous phases better. The new crystalline lithium oxonitridophosphate Li5+xP2O6−xN1+x was synthesized as an off-white powder by ampoule synthesis at 750\textendash800 °C under Ar atmosphere. It crystallizes in the monoclinic space group P21/c with a=15.13087(11) r{A}},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals},

author = {G Reuveni and Y Diskin-Posner and C Gehrmann and S Godse and G G Gkikas and I Buchine and S Aharon and R Korobko and C C Stoumpos and D A Egger},

url = {https://arxiv.org/abs/2211.06904},

doi = {https://doi.org/10.48550/arXiv.2211.06904},

year  = {2022},

date = {2022-11-13},

journal = {arXiv preprint arXiv:2211.06904},

abstract = {We show that formamidinium lead bromide is unique among the halide perovskite crystals because its inorganic sub-lattice exhibits intrinsic local static disorder that co-exists with a well-defined average crystal structure. Our study combines THz-range Raman-scattering with single-crystal X-ray diffraction and first-principles calculations to probe the inorganic sub-lattice dynamics evolution with temperature in the range of 10-300 K. The temperature evolution of the Raman spectra shows that low-temperature, local static disorder strongly affects the crystal's structural dynamics and phase transitions at higher temperatures.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Ground-state structures, electronic structure, transport properties and optical properties of Ca-based anti-Ruddlesden-Popper phase oxide perovskites},

author = {D Han and M-H Du and M Huang and S Wang and G Tang and T Bein and H Ebert},

url = {https://link.aps.org/doi/10.1103/PhysRevMaterials.6.114601},

doi = {10.1103/PhysRevMaterials.6.114601},

year  = {2022},

date = {2022-11-07},

journal = {Physical Review Materials},

volume = {6},

number = {11},

pages = {114601},

abstract = {Anti-Ruddlesden-Popper (ARP) phase oxide perovskites Ca4OA2 (A=P, As, Sb, Bi) have recently attracted great interest in the field of ferroelectrics and thermoelectrics, whereas their optoelectronic application is limited by their indirect band gaps. In this work, we introduce A-site anion ordering in Ca4OA2 (A=P, As, Sb, Bi), and find that it induces an indirect-to-direct band gap transition. Using first-principles calculations, we study the ground-state structures, electronic structure, transport properties and optical properties of anion-ordered ARP phase oxide perovskites Ca4OAA′. Based on analyses of the lattice dynamics, the ground-state structures of Ca4OAsSb and Ca4OAsBi are identified in P4/nmm symmetry and those of Ca4OPSb and Ca4OPBi are in the I222 symmetry. In contrast to the Ruddlesden-Popper (RP) phase oxide and halide counterparts, Ca4OAA′ (AA′=PSb, PBi, AsSb, AsBi) show larger band dispersion along the out-of-plane direction, smaller band gaps and highly enhanced out-of-plane mobilities, which results from the short interlayer distances and the enhanced covalency of the pnictides. Although the out-of-plane mobilities of these n=1 ARP phase perovskites highly increase, the comparatively strong polar optical phonon scattering limits the further enhancement of their mobilities. Furthermore, compared to RP phase halide Cs2PbI2Cl2, Ca4OAA′ show strong optical absorption around the band edges, and their optical absorption coefficients can reach 10^5 cm−1 within the visible light region due to small band gaps. This study reveals that these ARP phase oxide perovskites exhibit the potential for optoelectronic applications.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Mapping structure heterogeneities and visualizing moisture degradation of perovskite films with nano-focus WAXS},

author = {N Li and S Pratap and V K\"{o}rstgens and S Vema and L Song and S Liang and A Davydok and C Krywka and P M\"{u}ller-Buschbaum},

url = {https://doi.org/10.1038/s41467-022-34426-y},

doi = {10.1038/s41467-022-34426-y},

issn = {2041-1723},

year  = {2022},

date = {2022-11-05},

journal = {Nature Communications},

volume = {13},

number = {1},

pages = {6701},

abstract = {Extensive attention has focused on the structure optimization of perovskites, whereas rare research has mapped the structure heterogeneity within mixed hybrid perovskite films. Overlooked aspects include material and structure variations as a function of depth. These depth-dependent local structure heterogeneities dictate their long-term stabilities and efficiencies. Here, we use a nano-focused wide-angle X-ray scattering method for the mapping of film heterogeneities over several micrometers across lateral and vertical directions. The relative variations of characteristic perovskite peak positions show that the top film region bears the tensile strain. Through a texture orientation map of the perovskite (100) peak, we find that the perovskite grains deposited by sequential spray-coating grow along the vertical direction. Moreover, we investigate the moisture-induced degradation products in the perovskite film, and the underlying mechanism for its structure-dependent degradation. The moisture degradation along the lateral direction primarily initiates at the perovskite-air interface and grain boundaries. The tensile strain on the top surface has a profound influence on the moisture degradation.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Alkali metal cations change the hydrogen evolution reaction mechanisms at Pt electrodes in alkaline media},

author = {Y Taji and A Zagalskaya and I Evazzade and S Watzele and K-T Song and S Xue and C Schott and B Garlyyev and V Alexandrov and E Gubanova and A S Bandarenka},

url = {https://www.sciencedirect.com/science/article/pii/S2589965122000514},

doi = {https://doi.org/10.1016/j.nanoms.2022.09.003},

issn = {2589-9651},

year  = {2022},

date = {2022-10-29},

journal = {Nano Materials Science},

abstract = {The effects of seemingly inert alkali metal (AM) cations on the electrocatalytic activity of electrode materials towards reactions essential for energy provision have become the emphasis of substantial research efforts in recent years. The hydrogen and oxygen evolution reactions during alkaline water electrolysis and the oxygen electro-reduction taking place in fuel cells are of particular importance. There is no universal theory explaining all the details of the AM cation effect in electrocatalysis. For example, it remains unclear how “spectator” AM-cations can change the kinetics of electrocatalytic reactions often more significantly than the modifications of the electrode structure and composition. This situation originates partly from a lack of systematic experimental and theoretical studies of this phenomenon. The present work exploits impedance spectroscopy to investigate the influence of the AM cations on the mechanism of the hydrogen evolution reaction at Pt microelectrodes. The activity follows the trend: Li+≥Na+\>K+\>Cs+, where the highest activity corresponds to 0.1 ​M LiOH electrolytes at low overpotentials. We demonstrate that the nature of the AM cations also changes the relative contribution of the Volmer\textendashHeyrovsky and Volmer\textendashTafel mechanisms to the overall reaction, with the former being more important for LiOH electrolytes. Our density functional theory-based thermodynamics and molecular dynamics calculations support these findings.},

keywords = {Foundry Inorganic, Solid-Liquid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {A Switchable One-Compound Diode},

author = {A Vogel and A Rabenbauer and P Deng and R Steib and T B\"{o}ger and W G Zeier and R Siegel and J Senker and D Daisenberger and K Nisi and A W Holleitner and J Venturini and T Nilges},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202208698},

doi = {https://doi.org/10.1002/adma.202208698},

issn = {0935-9648},

year  = {2022},

date = {2022-10-25},

journal = {Advanced Materials},

volume = {n/a},

number = {n/a},

pages = {2208698},

abstract = {Abstract A diode or transistor requires the combination of p- and n-type semiconductors or at least the defined formation of such areas within a given compound. This is a prerequisite for any IT application, energy conversion technology, and electronic semiconductor devices. Since 2009, when the first pnp-switchable compound Ag10Te4Br3 was described, it is in principle possible to fabricate a diode from a single material without adjusting the semiconduction type by a defined doping level. After this discovery, a handful of other materials that are capable of reversibly switching between these two semiconducting stages was reported. In all cases, a structural phase transition accompanied by a dynamic change of charge carriers or a charge density wave (CDW) within certain substructures are responsible for this effect. Unfortunately, a certain feature hinders the application of this phenomenon in convenient devices, namely the pnp-switching temperature, which generally occurs well above room temperature, between 364 and 580 K. This effect is far removed from a suitable operation temperature at ambient conditions. Here, we report on Ag18Cu3Te11Cl3, a room temperature pnp-switching material, and the realization of the first single-material position-independent diode. The title compound shows the highest ever reported Seebeck coefficient drop that takes place within a few Kelvin at room temperature. Combined with its reasonably low thermal conductivity, this material offers great application potential within an easily accessible and applicable temperature window. Ag18Cu3Te11Cl3 and pnp-switching materials have the potential for applications and processes where diodes, transistors, or any defined charge separation with junction formation are utilized. This article is protected by copyright. All rights reserved},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Hot Carrier Dynamics in InAs-AlAsSb Core-Shell Nanowires},

author = {D Sandner and H Esmaielpour and F Del Giudice and M Nuber and R Kienberger and G Koblm\"{u}ller and H Iglev},

url = {https://arxiv.org/abs/2210.11886},

doi = {https://doi.org/10.48550/arXiv.2210.11886},

year  = {2022},

date = {2022-10-25},

journal = {arXiv preprint arXiv:2210.11886},

abstract = {Semiconductor nanowires (NWs) have shown evidence of robust hot carrier effects due to their small dimensions. The relaxation dynamics of hot carriers in these nanostructures, generated by photo-absorption, are of great importance in optoelectronic devices and high efficiency solar cells, such as hot carrier solar cells. Among various III-V semiconductors, indium arsenide (InAs) NWs are promising candidates for their applications in advanced light harvesting devices due to their high photo-absorptivity and high mobility. Here, we investigate the hot carrier dynamics in InAs-AlAsSb core-shell NWs, as well as bare-core InAs NWs, using ultrafast pump-probe spectroscopy with widely tuned pump and probe energies. We have found a lifetime of 2.3 ps for longitudinal optical (LO) phonons and hot electron lifetimes of about 3 ps and 30 ps for carrier-carrier interactions and electron-phonon interactions, respectively. In addition, we have investigated the electronic states in the AlAsSb-shell and found that, despite the large band offset of the core-shell design in the conduction band, excited carriers remain in the shell longer than 100 ps. Our results indicate evidence of plasmon-tailored core-shell NWs for efficient light harvesting devices, which could open potential avenues for improving the efficiency of photovoltaic solar cells.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Crystal side facet-tuning of GaN nanowires and nanofins grown by molecular beam epitaxy},

author = {F Pantle and M Karlinger and S W\"{o}rle and F Becker and T H\"{o}ldrich and E Sirotti and M Kraut and M Stutzmann},

url = {https://aip.scitation.org/doi/abs/10.1063/5.0098016},

doi = {10.1063/5.0098016},

year  = {2022},

date = {2022-10-22},

journal = {Journal of Applied Physics},

volume = {132},

number = {18},

pages = {184304},

abstract = {GaN nanostructures are promising for a broad range of applications due to their 3D structure, thereby exposing non-polar crystal surfaces. The nature of the exposed crystal facets, i.e., whether they are a-, m-plane, or of mixed orientation, impacts the stability and performance of GaN nanostructure-based devices. In this context, it is of great interest to control the formation of well-defined side facets. Here, we show that we can control the crystal facet formation at the nanowire sidewalls by tuning the III\textendashV ratio during selective area growth by molecular beam epitaxy. Especially, the N flux serves as a tool for controlling the growth kinetics. In addition, we demonstrate the growth of GaN nanofins with either a- or m-plane side facets. Based on our observations, we present the underlying nanostructure growth mechanisms. Low temperature photoluminescence measurements show a correlation of the formation of structural defects like stacking faults with the growth kinetics. This article demonstrates the controlled selective epitaxy of GaN nanostructures with defined crystal side facets on large-scale available AlN substrates.},

keywords = {Foundry Inorganic, Molecularly-Functionalized},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Near-Field Retrieval of the Surface Phonon Polariton Dispersion in Free-Standing Silicon Carbide Thin Films},

author = {A Mancini and L Nan and F J Wendisch and R Bert\'{e} and H Ren and E Cort\'{e}s and S A Maier},

url = {https://doi.org/10.1021/acsphotonics.2c01270},

doi = {10.1021/acsphotonics.2c01270},

year  = {2022},

date = {2022-10-20},

journal = {ACS Photonics},

abstract = {Surface phonon polaritons (SPhPs) are mixed light-matter states originating from strong coupling of photons with lattice vibrations. Thin films of polar dielectrics feature a splitting of the SPhP branch due to the hybridization of the top and bottom interface modes. Recently, enhanced in-plane thermal conductivity and near-field energy transfer have been experimentally demonstrated in free-standing polar films. These effects are determined by the SPhP dispersion in these systems, which, however, is yet to be reported experimentally. In this work, we retrieve the SPhP dispersion in silicon carbide free-standing membranes few hundreds of nanometers thick through near-field spectroscopy. We find several branches in the experimental dispersion, which we rationalize as multiple reflections of tip and edge launched SPhPs, in good agreement with theoretical predictions. Our work paves the way to employ large-area free-standing membranes as a platform for phonon polaritonics, with foreseeable applications in the field of thermal management at the nanoscale.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Excitons at the Phase Transition of 2D Hybrid Perovskites},

author = {J D Ziegler and K-Q Lin and B Meisinger and X Zhu and M Kober-Czerny and P K Nayak and C Vona and T Taniguchi and K Watanabe and C Draxl and H J Snaith and J M Lupton and D A Egger and A Chernikov},

url = {https://doi.org/10.1021/acsphotonics.2c01035},

doi = {10.1021/acsphotonics.2c01035},

year  = {2022},

date = {2022-10-18},

journal = {ACS Photonics},

abstract = {2D halide perovskites are among intensely studied materials platforms profiting from solution-based growth and chemical flexibility. They feature exceptionally strong interactions among electronic, optical, as well as vibrational excitations and hold a great potential for future optoelectronic applications. A key feature for these materials is the occurrence of structural phase transitions that can impact their functional properties, including the electronic band gap and optical response dominated by excitons. However, to what extent the phase transitions in 2D perovskites alter the fundamental exciton properties remains barely explored so far. Here, we study the influence of the phase transition on both exciton binding energy and exciton diffusion, demonstrating their robust nature across the phase transition. These findings are unexpected in view of the associated substantial changes of the free carrier masses, strongly contrast broadly considered effective mass and drift-diffusion transport mechanisms, highlighting the unusual nature of excitons in 2D perovskites.},

keywords = {Foundry Inorganic},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Machine-Learning-Optimized Perovskite Nanoplatelet Synthesis},

author = {C Lampe and I Kouroudis and M Harth and S Martin and A Gagliardi and A S Urban},

url = {https://arxiv.org/abs/2210.09783},

doi = {https://doi.org/10.48550/arXiv.2210.09783},

year  = {2022},

date = {2022-10-18},

journal = {arXiv preprint arXiv:2210.09783},

abstract = {With the demand for renewable energy and efficient devices rapidly increasing, a need arises to find and optimize novel (nano)materials. This can be an extremely tedious process, often relying significantly on trial and error. Machine learning has emerged recently as a powerful alternative; however, most approaches require a substantial amount of data points, i.e., syntheses. Here, we merge three machine-learning models with Bayesian Optimization and are able to dramatically improve the quality of CsPbBr3 nanoplatelets (NPLs) using only approximately 200 total syntheses. The algorithm can predict the resulting PL emission maxima of the NPL dispersions based on the precursor ratios, which lead to previously unobtainable 7 and 8 ML NPLs. Aided by heuristic knowledge, the algorithm should be easily applicable to other nanocrystal syntheses and significantly help to identify interesting compositions and rapidly improve their quality.},

keywords = {Foundry Inorganic, Solid-Solid},

pubstate = {published},

tppubtype = {article}

}