TY - GEN A1 - Bär, Marcus A1 - Schubert, Björn-Arvid A1 - Marsen, Björn A1 - Wilks, Regan G. A1 - Pookpanratana, Sujitra A1 - Blum, Monika A1 - Krause, Stefan A1 - Unold, Thomas A1 - Yang, Wan Li A1 - Weinhardt, Lothar A1 - Heske, Clemens A1 - Schock, Hans-Werner T1 - Cliff-like conduction band offset and KCN-induced recombination barrier enhancement at the CdS/Cu2ZnSnS4 thin-film solar cell heterojunction N2 - The electronic structure of the CdS/Cu2ZnSnS4 (CZTS) heterojunction was investigated by direct and inverse photoemission. The effects of a KCN etch of the CZTS absorber prior to CdS deposition on the band alignment at the respective interface were studied. We find a “cliff”-like conduction band offset at the CdS/CZTS interface independent of absorber pretreatment and a significant etch-induced enhancement of the energetic barrier for charge carrier recombination across the CdS/CZTS interface. KW - kesterite KW - thin-film solar cells KW - energy band alignment Y1 - 2011 ER - TY - GEN A1 - Sullivan, J. T. A1 - Wilks, Regan G. A1 - Winkler, M. T. A1 - Weinhardt, Lothar A1 - Recht, D. A1 - Said, A. J. A1 - Newman, B. K. A1 - Zhang, Y. A1 - Blum, Monika A1 - Krause, S. A1 - Yang, Wan Li A1 - Heske, Clemens A1 - Aziz, M. J. A1 - Bär, Marcus A1 - Buonassisi, T. T1 - Soft x-ray emission spectroscopy studies of the electronic structure of silicon supersaturated with sulfur N2 - We apply soft x-ray emission spectroscopy (XES) to measure the electronic structure of crystalline silicon supersaturated with sulfur (up to 0.7 at. %), a candidate intermediate-band solar cell material. Si L2,3 emission features are observed above the conventional Si valence band maximum, with intensity scaling linearly with S concentration. The lineshape of the S-induced features change across the insulator-to-metal transition, indicating a significant modification of the local electronic structure concurrent with the change in macroscopic electronic behavior. The relationship between the Si L2,3 XES spectral features and the anomalously high sub-band gap infrared absorption is discussed. KW - black silicon KW - solar cells KW - electronic surface structure KW - x-ray emission spectroscopy Y1 - 2011 ER - TY - GEN A1 - Weinhardt, Lothar A1 - Benkert, Andreas A1 - Meyer, Frank A1 - Blum, Monika A1 - Wilks, Regan G. A1 - Yang, Wan Li A1 - Bär, Marcus A1 - Reinert, Friedrich A1 - Heske, Clemens T1 - Nuclear dynamics and spectator effects in resonant inelastic soft x-ray scattering of gas-phase water molecules T2 - The journal of chemical physics N2 - The electronic structure of gas-phase H2O and D2O molecules has been investigated using resonant inelastic soft x-ray scattering (RIXS). We observe spectator shifts for all valence orbitals when exciting into the lowest three absorption resonances. Strong changes of the relative valence orbital emission intensities are found when exciting into the different absorption resonances, which can be related to the angular anisotropy of the RIXS process. Furthermore, excitation into the 4a1 resonance leads to nuclear dynamics on the time scale of the RIXS process; we find evidence for vibrational coupling and molecular dissociation in both, the spectator and the participant emission. Y1 - 2012 SN - 1089-7690 VL - 136 IS - 14 SP - 144311 ER - TY - GEN A1 - Bär, Marcus A1 - Klaer, Joachim A1 - Weinhardt, Lothar A1 - Wilks, Regan G. A1 - Krause, Stefan A1 - Blum, Monika A1 - Yang, Wan Li A1 - Heske, Clemens A1 - Schock, Hans-Werner T1 - Cu 2−x S Surface Phases and Their Impact on the Electronic Structure of CuInS 2 Thin Films – A Hidden Parameter in Solar Cell Optimization T2 - Advanced Energy Materials N2 - The surface properties of CuInS 2 (CIS) thin-fi lm solar cell absorbers are investigated by a combination of electron and soft X-ray spectroscopies. Spatially separated regions of varying colors are observed and identifi ed to be dominated by either CuS or Cu 2 S surface phases. After their removal by KCN etching, the samples cannot be distinguished by eye and the CIS surface is found to be Cu-defi cient in both regions. However, a signifi cantly more pronounced off-stoichiometry in the region initially covered by Cu 2 S can be identifi ed. In this region, the resulting surface band gap is also signifi cantly larger than the E g Surf of the initially CuS-terminated region. Such variations may represent a hidden parameter which, if overlooked, induces irreproducibility and thus prevents systematic optimization efforts. Y1 - 2013 SN - 1614-6840 VL - 3 IS - 6 SP - 777 EP - 781 ER - TY - GEN A1 - Bär, Marcus A1 - Couziniè-Devy, François A1 - Duarte, Roberto Felix A1 - Klaer, Joachim A1 - Pookpanratana, Sujitra A1 - Blum, Monika A1 - Zhang, Yi A1 - Denlinger, Jonathan D. A1 - Yang, Wanli A1 - Wilks, Regan G. A1 - Weinhardt, Lothar A1 - Schock, Hans-Werner A1 - Southerland Kessler, Jude A1 - Heske, Clemens T1 - The Heavily Intermixed In2S3/Cu(In,Ga)Se2 Interface as Revealed by Photoelectron and Soft X-ray Emission Spectroscopy T2 - 2013 IEEE 39th Photovoltaic Specialists Conference, (PVSC 2013), Tampa, Florida, USA, 16 - 21 June 2013 Y1 - 2013 SN - 978-1-4799-3300-6 SN - 978-1-4799-3299-3 U6 - https://doi.org/10.1109/PVSC.2013.6744280 SP - 857 EP - 862 PB - IEEE CY - Piscataway, NJ ER - TY - GEN A1 - Benkert, Andreas A1 - Meyer, Frank A1 - Hauschild, Dirk A1 - Blum, Monika A1 - Yang, Wooyong A1 - Wilks, Regan G. A1 - Bär, Marcus A1 - Reinert, Friedrich A1 - Heske, Clemens A1 - Weinhardt, Lothar T1 - Isotope Effects in the Resonant Inelastic Soft X-ray Scattering Maps of Gas-Phase Methanol T2 - The Journal of Physical Chemistry: A Y1 - 2016 U6 - https://doi.org/10.1021/acs.jpca.6b02636 SN - 1089-5639 SN - 1520-5215 VL - 120 IS - 14 SP - 2260 EP - 2267 ER - TY - GEN A1 - Duncan, Douglas A. A1 - Kephart, Jason M. A1 - Horsley, Kimberly A1 - Blum, Monika A1 - Mezher, Michelle A1 - Weinhardt, Lothar A1 - Häming, Marc A1 - Wilks, Regan G. A1 - Hofmann, Timo A1 - Yang, Wanli A1 - Bär, Marcus A1 - Sampath, Walajabad S. A1 - Heske, Clemens T1 - Characterization of sulfur bonding in CdS:O buffer layers for CdTe-based thin-film solar cells T2 - ACS Applied Materials & Interfaces Y1 - 2015 U6 - https://doi.org/10.1021/acsami.5b03503 SN - 1944-8244 SN - 1944-8252 VL - 7 IS - 30 SP - 16382 EP - 16386 ER - TY - GEN A1 - Hauschild, Dirk A1 - Meyer, Frank A1 - Benkert, Andreas A1 - Kreikemeyer-Lorenzo, Dagmar A1 - Pohlner, Stephan A1 - Palm, Jörg A1 - Blum, Monika A1 - Yang, Wanli A1 - Wilks, Regan G. A1 - Bär, Marcus A1 - Heske, Clemens A1 - Weinhardt, Lothar A1 - Reinert, Friedrich T1 - Annealing-induced effects on the chemical structure of the In₂S₃/CuIn(S,Se)₂ thin-film solar cell interface T2 - The Journal of Physical Chemistry: C, Nanomaterials and interfaces Y1 - 2015 U6 - https://doi.org/10.1021/acs.jpcc.5b01622 SN - 1932-7447 SN - 1932-7455 VL - 119 IS - 19 SP - 10412 EP - 10416 ER -