@article{19844, abstract = {{The defect-electronic properties of {112} microfaceted surfaces of epitaxially grown CuInSe2 thin films are investigated by scanning tunneling spectroscopy and photoelectron spectroscopy techniques after various surface treatments. The intrinsic CuInSe2 surface is found to be largely passivated in terms of electronic defect levels in the band-gap region. However, surface oxidation leads to an overall high density of defect levels in conjunction with a considerable net surface dipole, which persists even after oxide removal. Yet, a subsequent annealing under vacuum restores the initial condition. Such oxidation/reduction cycles are reversible for many times providing robust control of the surface and interface properties in these materials. Based on ab initio simulations, a mechanism where oxygen dissociatively adsorbs and subsequently diffuses to a subsurface site is proposed as the initial step of the observed dipole formation. Our results emphasize the relevance of oxidation-induced dipole effects at the thin film surface and provide a comprehensive understanding toward passivation strategies of these surfaces.}}, author = {{Elizabeth, Amala and Sahoo, Sudhir K. and Lockhorn, David and Timmer, Alexander and Aghdassi, Nabi and Zacharias, Helmut and Kühne, Thomas and Siebentritt, Susanne and Mirhosseini, Hossein and Mönig, Harry}}, journal = {{Phys. Rev. Materials}}, pages = {{063401}}, publisher = {{American Physical Society}}, title = {{{ Oxidation/reduction cycles and their reversible effect on the dipole formation at CuInSe2 surfaces}}}, doi = {{10.1103/PhysRevMaterials.4.063401}}, volume = {{4}}, year = {{2020}}, } @article{21112, abstract = {{Photovoltaics is one of the most promising and fastest-growing renewable energy technologies. Although the price-performance ratio of solar cells has improved significantly over recent years{,} further systematic investigations are needed to achieve higher performance and lower cost for future solar cells. In conjunction with experiments{,} computer simulations are powerful tools to investigate the thermodynamics and kinetics of solar cells. Over the last few years{,} we have developed and employed advanced computational techniques to gain a better understanding of solar cells based on copper indium gallium selenide (Cu(In{,}Ga)Se2). Furthermore{,} we have utilized state-of-the-art data-driven science and machine learning for the development of photovoltaic materials. In this Perspective{,} we review our results along with a survey of the field.}}, author = {{Mirhosseini, S. Hossein and Kormath Madam Raghupathy, Ramya and Sahoo, Sudhir K. and Wiebeler, Hendrik and Chugh, Manjusha and Kühne, Thomas}}, journal = {{Phys. Chem. Chem. Phys.}}, pages = {{26682--26701}}, publisher = {{The Royal Society of Chemistry}}, title = {{{In silico investigation of Cu(In,Ga)Se2-based solar cells}}}, doi = {{10.1039/D0CP04712K}}, volume = {{22}}, year = {{2020}}, } @article{21240, abstract = {{Rechargeable aqueous Zn-ion energy storage devices are promising candidates for next-generation energy storage technologies. However, the lack of highly reversible Zn2+-storage anode materials with low potential windows remains a primary concern. Here, we report a two-dimensional polyarylimide covalent organic framework (PI-COF) anode with high-kinetics Zn2+-storage capability. The well-organized pore channels of PI-COF allow the high accessibility of the build-in redox-active carbonyl groups and efficient ion diffusion with a low energy barrier. The constructed PI-COF anode exhibits a specific capacity (332 C g–1 or 92 mAh g–1 at 0.7 A g–1), a high rate capability (79.8% at 7 A g–1), and a long cycle life (85% over 4000 cycles). In situ Raman investigation and first-principle calculations clarify the two-step Zn2+-storage mechanism, in which imide carbonyl groups reversibly form negatively charged enolates. Dendrite-free full Zn-ion devices are fabricated by coupling PI-COF anodes with MnO2 cathodes, delivering excellent energy densities (23.9 ∼ 66.5 Wh kg–1) and supercapacitor-level power densities (133 ∼ 4782 W kg–1). This study demonstrates the feasibility of covalent organic framework as Zn2+-storage anodes and shows a promising prospect for constructing reliable aqueous energy storage devices.}}, author = {{Yu, Minghao and Chandrasekhar, Naisa and Kormath Madam Raghupathy, Ramya and Ly, Khoa Hoang and Zhang, Haozhe and Dmitrieva, Evgenia and Liang, Chaolun and Lu, Xihong and Kühne, Thomas and Mirhosseini, S. Hossein and Weidinger, Inez M. and Feng, Xinliang}}, issn = {{0002-7863}}, journal = {{Journal of the American Chemical Society}}, number = {{46}}, pages = {{19570--19578}}, publisher = {{American Chemical Society}}, title = {{{A High-Rate Two-Dimensional Polyarylimide Covalent Organic Framework Anode for Aqueous Zn-Ion Energy Storage Devices}}}, doi = {{10.1021/jacs.0c07992}}, volume = {{142}}, year = {{2020}}, } @article{17374, abstract = {{Lead halide perovskite semiconductors providing record efficiencies of solar cells have usually mixed compositions doped in A- and X-sites to enhance the phase stability. The cubic form of formamidinium (FA) lead iodide reveals excellent opto-electronic properties but transforms at room temperature (RT) into a hexagonal structure which does not effectively absorb visible light. This metastable form and the mechanism of its stabilization by Cs+ and Br− incorporation are poorly characterized and insufficiently understood. We report here the vibrational properties of cubic FAPbI3 investigated by DFT calculations on phonon frequencies and intensities, and micro-Raman spectroscopy. The effects of Cs+ and Br− partial substitution are discussed. We support our results with the study of FAPbBr3 which expands the identification of vibrational modes to the previously unpublished low frequency region (<500 cm−1). Our results show that the incorporation of Cs+ and Br− leads to the coupling of the displacement of the A-site components and weakens the bonds between FA+ and the PbX6 octahedra. We suggest that the enhancement of α-FAPbI3 stability can be a product of the release of tensile stresses in the Pb–X bond, which is reflected in a red-shift of the low frequency region of the Raman spectrum (<200 cm−1).}}, author = {{Ibaceta-Jaña, Josefa and Muydinov, Ruslan and Rosado, Pamela and Mirhosseini, Hossein and Chugh, Manjusha and Nazarenko, Olga and Dirin, Dmitry N. and Heinrich, Dirk and Wagner, Markus R. and Kühne, Thomas and Szyszka, Bernd and Kovalenko, Maksym V. and Hoffmann, Axel}}, journal = {{Phys. Chem. Chem. Phys.}}, pages = {{5604--5614}}, publisher = {{The Royal Society of Chemistry}}, title = {{{Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy}}}, doi = {{10.1039/C9CP06568G}}, volume = {{22}}, year = {{2020}}, } @article{17376, abstract = {{The record conversion efficiency of thin-film solar cells based on Cu(In,Ga)Se2 (CIGS) absorbers has exceeded 23%. Such a high performance is currently only attainable by the incorporation of heavy alkali metals like Cs into the absorber through an alkali fluoride post-deposition treatment (PDT). As the effect of the incorporated heavy alkali metals is under discussion, we investigated the local composition and microstructure of high efficiency CIGS solar cells via various high-resolution techniques in a combinatory approach. An accumulation of Cs is clearly detected at the p-n junction along with variations in the local CIGS composition, showing the formation of a beneficial secondary phase with a laterally inhomogeneous distribution. Additionally, Cs accumulations were detected at grain boundaries with a random misorientation of the adjacent grains where a reduced Cu concentration and increased In and Se concentrations are detected. No accumulation was found at Σ3 twin boundaries as well as the grain interior. These experimental findings are in excellent agreement with complementary ab-initio calculations, demonstrating that the grain boundaries are passivated by the presence of Cs. Further, it is unlikely that Cs with its large ionic radius is incorporated into the CIGS grains where it would cause detrimental defects.}}, author = {{Schöppe, Philipp and Schönherr, Sven and Chugh, Manjusha and Mirhosseini, Hossein and Jackson, Philip and Wuerz, Roland and Ritzer, Maurizio and Johannes, Andreas and Martínez-Criado, Gema and Wisniewski, Wolfgang and Schwarz, Torsten and T. Plass, Christian and Hafermann, Martin and Kühne, Thomas and S. Schnohr, Claudia and Ronning, Carsten}}, issn = {{2211-2855}}, journal = {{Nano Energy}}, pages = {{104622}}, title = {{{Revealing the origin of the beneficial effect of cesium in highly efficient Cu(In,Ga)Se2 solar cells}}}, doi = {{https://doi.org/10.1016/j.nanoen.2020.104622}}, volume = {{71}}, year = {{2020}}, } @article{33646, author = {{Majumdar, I. and Sahoo, S.K. and Parvan, V. and Mirhosseini, Hossein and Chacko, B. and Wang, Y. and Greiner, D. and Kühne, Thomas and Schlatmann, R. and Lauermann, I.}}, issn = {{0169-4332}}, journal = {{Applied Surface Science}}, keywords = {{Surfaces, Coatings and Films, Condensed Matter Physics, Surfaces and Interfaces, General Physics and Astronomy, General Chemistry}}, publisher = {{Elsevier BV}}, title = {{{Effects of KF and RbF treatments on Cu(In,Ga)Se2-based solar cells: A combined photoelectron spectroscopy and DFT study}}}, doi = {{10.1016/j.apsusc.2020.148085}}, volume = {{538}}, year = {{2020}}, } @article{33647, author = {{Kossmann, Janina and Piankova, Diana and Tarakina, Nadezda V. and Heske, Julian Joachim and Kühne, Thomas and Schmidt, Johannes and Antonietti, Markus and López-Salas, Nieves}}, issn = {{0008-6223}}, journal = {{Carbon}}, keywords = {{General Chemistry, General Materials Science}}, pages = {{497--505}}, publisher = {{Elsevier BV}}, title = {{{Guanine condensates as covalent materials and the concept of cryptopores}}}, doi = {{10.1016/j.carbon.2020.10.047}}, volume = {{172}}, year = {{2020}}, } @article{44995, author = {{Dreßler, C. and Kabbe, G. and Brehm, Martin and Sebastiani, D.}}, journal = {{J. Chem. Phys.}}, pages = {{164110}}, title = {{{Exploring Non-Equilibrium Molecular Dynamics of Mobile Protons in the Solid Acid CsH2PO4 on the Micrometer and Microsecond Scale}}}, doi = {{10.1063/5.0002167}}, volume = {{152 (16)}}, year = {{2020}}, } @article{44997, author = {{Brehm, Martin and Radicke, J. and Pulst, M. and Shaabani, F. and Sebastiani, D. and Kressler, J.}}, journal = {{Molecules}}, pages = {{3539}}, title = {{{Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions}}}, doi = {{10.3390/molecules25153539}}, volume = {{25 (15)}}, year = {{2020}}, } @article{44998, author = {{Hunold, J. and Eisermann, J. and Brehm, Martin and Hinderberger, D.}}, journal = {{J. Phys. Chem. B}}, pages = {{8601--8609}}, title = {{{Characterization of Aqueous Lower Polarity Solvation Shells Around Amphiphilic TEMPO Radicals in Water}}}, doi = {{10.1021/acs.jpcb.0c04863}}, volume = {{124 (39)}}, year = {{2020}}, } @article{44993, author = {{Scarbath-Evers, L. and Hammer, R. and Golze, D. and Brehm, Martin and Sebastiani, D. and Widdra, W.}}, journal = {{Nanoscale}}, pages = {{3834--3845}}, title = {{{From Flat to Tilted: Gradual Interfaces in Organic Thin Film Growth}}}, doi = {{10.1039/C9NR06592J}}, volume = {{12}}, year = {{2020}}, } @article{44994, author = {{Dreßler, C. and Kabbe, G. and Brehm, Martin and Sebastiani, D.}}, journal = {{J. Chem. Phys.}}, pages = {{114114}}, title = {{{Dynamical Matrix Propagator Scheme for Large-Scale Proton Dynamics Simulations}}}, doi = {{10.1063/1.5140635}}, volume = {{152 (11)}}, year = {{2020}}, } @article{44999, author = {{Weiß, M. and Brehm, Martin}}, journal = {{Molecules}}, pages = {{5861}}, title = {{{Exploring Free Energy Profiles of Enantioselective Organocatalytic Aldol Reactions under Full Solvent Influence}}}, doi = {{10.3390/molecules25245861}}, volume = {{25 (24)}}, year = {{2020}}, } @article{44996, author = {{Brehm, Martin and Thomas, M. and Gehrke, S. and Kirchner, B.}}, journal = {{J. Chem. Phys.}}, pages = {{164105}}, title = {{{TRAVIS – A Free Analyzer for Trajectories from Molecular Simulation}}}, doi = {{10.1063/5.0005078}}, volume = {{152 (16)}}, year = {{2020}}, } @article{16277, abstract = {{CP2K is an open source electronic structure and molecular dynamics software package to perform atomistic simulations of solid-state, liquid, molecular, and biological systems. It is especially aimed at massively parallel and linear-scaling electronic structure methods and state-of-theart ab initio molecular dynamics simulations. Excellent performance for electronic structure calculations is achieved using novel algorithms implemented for modern high-performance computing systems. This review revisits the main capabilities of CP2K to perform efficient and accurate electronic structure simulations. The emphasis is put on density functional theory and multiple post–Hartree–Fock methods using the Gaussian and plane wave approach and its augmented all-electron extension.}}, author = {{Kühne, Thomas and Iannuzzi, Marcella and Ben, Mauro Del and Rybkin, Vladimir V. and Seewald, Patrick and Stein, Frederick and Laino, Teodoro and Khaliullin, Rustam Z. and Schütt, Ole and Schiffmann, Florian and Golze, Dorothea and Wilhelm, Jan and Chulkov, Sergey and Mohammad Hossein Bani-Hashemian, Mohammad Hossein Bani-Hashemian and Weber, Valéry and Borstnik, Urban and Taillefumier, Mathieu and Jakobovits, Alice Shoshana and Lazzaro, Alfio and Pabst, Hans and Müller, Tiziano and Schade, Robert and Guidon, Manuel and Andermatt, Samuel and Holmberg, Nico and Schenter, Gregory K. and Hehn, Anna and Bussy, Augustin and Belleflamme, Fabian and Tabacchi, Gloria and Glöß, Andreas and Lass, Michael and Bethune, Iain and Mundy, Christopher J. and Plessl, Christian and Watkins, Matt and VandeVondele, Joost and Krack, Matthias and Hutter, Jürg}}, journal = {{The Journal of Chemical Physics}}, number = {{19}}, title = {{{CP2K: An electronic structure and molecular dynamics software package - Quickstep: Efficient and accurate electronic structure calculations}}}, doi = {{10.1063/5.0007045}}, volume = {{152}}, year = {{2020}}, } @inproceedings{16898, abstract = {{Electronic structure calculations based on density-functional theory (DFT) represent a significant part of today's HPC workloads and pose high demands on high-performance computing resources. To perform these quantum-mechanical DFT calculations on complex large-scale systems, so-called linear scaling methods instead of conventional cubic scaling methods are required. In this work, we take up the idea of the submatrix method and apply it to the DFT computations in the software package CP2K. For that purpose, we transform the underlying numeric operations on distributed, large, sparse matrices into computations on local, much smaller and nearly dense matrices. This allows us to exploit the full floating-point performance of modern CPUs and to make use of dedicated accelerator hardware, where performance has been limited by memory bandwidth before. We demonstrate both functionality and performance of our implementation and show how it can be accelerated with GPUs and FPGAs.}}, author = {{Lass, Michael and Schade, Robert and Kühne, Thomas and Plessl, Christian}}, booktitle = {{Proc. International Conference for High Performance Computing, Networking, Storage and Analysis (SC)}}, location = {{Atlanta, GA, US}}, pages = {{1127--1140}}, publisher = {{IEEE Computer Society}}, title = {{{A Submatrix-Based Method for Approximate Matrix Function Evaluation in the Quantum Chemistry Code CP2K}}}, doi = {{10.1109/SC41405.2020.00084}}, year = {{2020}}, } @article{12878, abstract = {{In scientific computing, the acceleration of atomistic computer simulations by means of custom hardware is finding ever-growing application. A major limitation, however, is that the high efficiency in terms of performance and low power consumption entails the massive usage of low precision computing units. Here, based on the approximate computing paradigm, we present an algorithmic method to compensate for numerical inaccuracies due to low accuracy arithmetic operations rigorously, yet still obtaining exact expectation values using a properly modified Langevin-type equation.}}, author = {{Rengaraj, Varadarajan and Lass, Michael and Plessl, Christian and Kühne, Thomas}}, journal = {{Computation}}, number = {{2}}, publisher = {{MDPI}}, title = {{{Accurate Sampling with Noisy Forces from Approximate Computing}}}, doi = {{10.3390/computation8020039}}, volume = {{8}}, year = {{2020}}, } @article{15738, author = {{Ohto, Tatsuhiko and Dodia, Mayank and Xu, Jianhang and Imoto, Sho and Tang, Fujie and Zysk, Frederik and Kühne, Thomas D. and Shigeta, Yasuteru and Bonn, Mischa and Wu, Xifan and Nagata, Yuki}}, issn = {{1948-7185}}, journal = {{The Journal of Physical Chemistry Letters}}, pages = {{4914--4919}}, title = {{{Accessing the Accuracy of Density Functional Theory through Structure and Dynamics of the Water–Air Interface}}}, doi = {{10.1021/acs.jpclett.9b01983}}, volume = {{10}}, year = {{2019}}, } @article{15740, author = {{Guc, Maxim and Kodalle, Tim and Kormath Madam Raghupathy, Ramya and Mirhosseini, Hossein and Kühne, Thomas D. and Becerril-Romero, Ignacio and Pérez-Rodríguez, Alejandro and Kaufmann, Christian A. and Izquierdo-Roca, Victor}}, issn = {{1932-7447}}, journal = {{The Journal of Physical Chemistry C}}, pages = {{1285--1291}}, title = {{{Vibrational Properties of RbInSe2: Raman Scattering Spectroscopy and First-Principle Calculations}}}, doi = {{10.1021/acs.jpcc.9b08781}}, volume = {{124}}, year = {{2019}}, } @article{16320, author = {{Müller, Patrick and Neuba, Adam and Flörke, Ulrich and Henkel, Gerald and Kühne, Thomas D. and Bauer, Matthias}}, issn = {{1089-5639}}, journal = {{The Journal of Physical Chemistry A}}, pages = {{3575--3581}}, title = {{{Experimental and Theoretical High Energy Resolution Hard X-ray Absorption and Emission Spectroscopy on Biomimetic Cu2S2 Complexes}}}, doi = {{10.1021/acs.jpca.9b00463}}, year = {{2019}}, }