@misc{BaerSchubertMarsenetal., author = {B{\"a}r, Marcus and Schubert, Bj{\"o}rn-Arvid and Marsen, Bj{\"o}rn and Wilks, Regan G. and Pookpanratana, Sujitra and Blum, Monika and Krause, Stefan and Unold, Thomas and Yang, Wan Li and Weinhardt, Lothar and Heske, Clemens and Schock, Hans-Werner}, title = {Cliff-like conduction band offset and KCN-induced recombination barrier enhancement at the CdS/Cu2ZnSnS4 thin-film solar cell heterojunction}, abstract = {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.}, language = {en} } @misc{BaerSongCaballeroetal., author = {B{\"a}r, Marcus and Song, X. and Caballero, R. and Duarte, Roberto Felix and Gerlach, Dominic and Kaufmann, Christian and Schock, Hans-Werner and Wilks, Regan G.}, title = {Na incorporation into Cu(In,Ga)Se2 thin-film solar cell absorbers deposited on polyimide: Impact on the chemical and electronic surface structure}, series = {Journal of Applied Physics}, volume = {111}, journal = {Journal of Applied Physics}, number = {3}, issn = {1089-7550}, pages = {034903}, abstract = {Na has deliberately been incorporated into Cu(In,Ga)Se2 ("CIGSe") chalcopyrite thin-film solar cell absorbers deposited on Mo-coated polyimide flexible substrates by adding differently thick layers of NaF in-between CIGSe absorber and Mo back contact. The impact of Na on the chemical and electronic surface structure of CIGSe absorbers with various Cu-contents deposited at comparatively low temperature (420 °C) has been studied using x-ray photoelectron and x-ray excited Auger electron spectroscopy. We observe a higher Nasurface content for the Cu-richer CIGSe samples and can distinguish between two different chemical Na environments, best described as selenide-like and oxidized Na species, respectively. Furthermore, we find a Cu-poor surface composition of the CIGSe samples independent of Na content and — for very high Na contents — indications for the formation of a (Cu,Na)-(In,Ga)-Se like compound. With increasing Nasurface content, also a shift of the photoemission lines to lower binding energies could be identified, which we interpret as a reduction of the downward band bending toward the CIGSe surface explained by the Na-induced elimination of InCu defects.}, language = {en} } @misc{BaerSchubertMarsenetal., author = {B{\"a}r, Marcus and Schubert, Bj{\"o}rn-Arvid and Marsen, Bj{\"o}rn and Wilks, Regan G. and Blum, M. and Krause, S. and Pookpanratana, Sujitra and Zhang, Y. and Unold, Thomas and Yang, W. and Weinhardt, Lothar and Heske, Clemens and Schock, Hans-Werner}, title = {Cu2ZnSnS4 thin-film solar cell absorbers illuminated by soft x-rays}, series = {Journal of Materials Research}, volume = {27}, journal = {Journal of Materials Research}, number = {8}, issn = {2044-5326}, doi = {10.1557/jmr.2012.59}, pages = {1097 -- 1104}, abstract = {In view of the complexity of thin-film solar cells, which are comprised of a multitude of layers, interfaces, surfaces, elements, impurities, etc., it is crucial to characterize and understand the chemical and electronic structure of these components. Because of the high complexity of the Cu2ZnSn(S,Se)4 compound semiconductor absorber material alone, this is particularly true for kesterite-based devices. Hence, this paper reviews our recent progress in the characterization of Cu2ZnSnS4 (CZTS) thin films. It is demonstrated that a combination of different soft x-ray spectroscopies is an extraordinarily powerful method for illuminating the chemical and electronic material characteristics from many different perspectives, ultimately resulting in a comprehensive picture of these properties. The focus of the article will be on secondary impurity phases, electronic structure, native oxidation, and the CZTS surface composition.}, language = {en} } @misc{WeinhardtBenkertMeyeretal., author = {Weinhardt, Lothar and Benkert, Andreas and Meyer, Frank and Blum, Monika and Wilks, Regan G. and Yang, Wan Li and B{\"a}r, Marcus and Reinert, Friedrich and Heske, Clemens}, title = {Nuclear dynamics and spectator effects in resonant inelastic soft x-ray scattering of gas-phase water molecules}, series = {The journal of chemical physics}, volume = {136}, journal = {The journal of chemical physics}, number = {14}, issn = {1089-7690}, pages = {144311}, abstract = {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.}, language = {en} } @misc{WilksRepinsContrerasetal., author = {Wilks, Regan G. and Repins, Ingrid and Contreras, M. A. and Duarte, Roberto Felix and Herrero-Albillos, J. and Tati-Bismaths, L. and Kronast, F. and Noufi, R. and B{\"a}r, Marcus}, title = {Intergrain variations of the chemical and electronic surface structure of polycrystalline Cu(In,Ga)Se2 thin-film solar cell absorbers}, series = {Applied Physics Letters}, volume = {101}, journal = {Applied Physics Letters}, number = {10}, issn = {0003-6951}, pages = {103908-1 -- 103908-4}, abstract = {The μm-scale spatial distribution of the elements of polycrystalline Cu(In1- x Ga x )Se2 absorber surfaces is examined using x-ray photoelectron emission microscopy. The chemical composition varies from grain to grain, and a direct, linear anticorrelation between the In 3d and Ga 2p photoemission line intensities is observed. The line intensities are interpreted in terms of a varying value of x= Ga/(In+ Ga); the band gaps calculated from the inferred compositions of the grains are shown to be normally distributed with a standard deviation of 40 meV.}, language = {en} } @misc{BlumOdeliusWeinhardtetal., author = {Blum, M. and Odelius, Michael and Weinhardt, Lothar and Pookpanratana, Sujitra and B{\"a}r, Marcus and Zhang, Y. and Fuchs, Oliver and Yang, W. and Umbach, Eberhard and Heske, Clemens}, title = {Ultrafast Proton Dynamics in Aqueous Amino Acid Solutions Studied by Resonant Inelastic Soft X‑ray Scattering}, series = {The Journal of physical chemistry : B}, volume = {116}, journal = {The Journal of physical chemistry : B}, number = {46}, issn = {1520-5207}, pages = {13757 -- 13764}, abstract = {Resonant inelastic soft X-ray scattering (RIXS) has been used to study the electronic structure of glycine and lysine in aqueous solution. Upon variation of the pH value of the solution from acidic to basic, major changes of the nitrogen K edge RIXS data are observed for both amino acids, which are associated with the protonation and deprotonation of the amino groups. The experimental results are compared with simulations based on density functional theory, yielding a detailed understanding of the spectral changes, as well as insights into the ultrafast proton dynamics in the intermediate core-excited/ionized state of the RIXS process.}, language = {en} } @misc{GerlachWipplerWilksetal., author = {Gerlach, Dominic and Wippler, David and Wilks, Regan G. and Wimmer, Manuel and Lozac'h, Micka{\"e}l and Duarte, Roberto Felix and Ueda, Shigenori and Yoshikawa, Hideki and Lips, Klaus and Rech, Bernd and Sumiya, Masatomo and Kobayashi, Kaoru and Gorgoi, Mihaela and H{\"u}pkes, J{\"u}rgen and B{\"a}r, Marcus}, title = {p-Type a-Si:H/ZnO:Al and μc-Si:H/ZnO:Al Thin-Film Solar Cell Structures—A Comparative Hard X-Ray Photoelectron Spectroscopy Study}, series = {IEEE journal of photovoltaics}, volume = {3}, journal = {IEEE journal of photovoltaics}, number = {1}, issn = {2156-3381}, pages = {483 -- 487}, abstract = {The chemical and electronic properties of a- Si:H(B)/ZnO:Al and μc-Si:H(B)/ZnO:Al thin-film solar cell structures are studied by hard X-ray photoelectron spectroscopy (HAXPES). Using a combination of different X-ray excitation energies and deliberate sample design, we were able to select the probed volume, i.e., the silicon capping layer only or the silicon and zinc oxide layer (including the buried interface). For the a-Si:H(B) material, we find a higher deposition rate and a smaller value for the modified Auger parameter than for μc-Si:H(B). In addition, we find indications of a pronounced band bending limited to the very surface of the a-Si:H(B) and the μc-Si:H(B) layers, which is more distinct in the latter case.}, language = {en} } @misc{MeyerWeinhardtBlumetal., author = {Meyer, Frank and Weinhardt, Lothar and Blum, Mia and B{\"a}r, Marcus and Wilks, Regan G. and Yang, Wooyong and Heske, Clemens and Reinert, F.}, title = {Non-equivalent carbon atoms in the resonant inelastic soft X-ray scattering map of cysteine}, series = {The journal of chemical physics}, volume = {138}, journal = {The journal of chemical physics}, number = {3}, issn = {1089-7690}, pages = {034306}, abstract = {Resonant inelastic soft x-ray scattering (RIXS) was used to study the electronic structure of solid cysteine films. A RIXS map approach, i.e., plotting the x-ray emission intensity as a function of excitation and emission energy, allows us to separate the contributions of the three chemically nonequivalent carbon atoms in cysteine. In particular, we can identify orbitals localized near the photoexcited atoms, as well as orbitals that are delocalized over the entire molecule.}, language = {en} } @misc{BaerKlaerDuarteetal., author = {B{\"a}r, Marcus and Klaer, Joachim and Duarte, Roberto Felix and Barreau, Nicolas and Weinhardt, Lothar and Wilks, Regan G. and Heske, Clemens and Schock, Hans-Werner}, title = {Surface Off-Stoichiometry of CuInS2 Thin-Film Solar Cell Absorbers}, series = {IEEE Journal of Photovoltaics}, volume = {3}, journal = {IEEE Journal of Photovoltaics}, number = {2}, issn = {2156-3381}, pages = {828 -- 832}, abstract = {In this paper, X-ray photoelectron and X-ray-excited Auger electron spectroscopy was used to investigate the chemical surface structure of CuInS2 thin-film solar cell absorbers.We find that the [In]/[Cu] surface composition can vary between 1.6 (±0.4) and 3.7 (±0.7), depending on relatively minor variations in the absorber formation process and/or whether additional wet-chemical treatments are performed. These variations are primarily due to differences in the Cu surface concentration. The corresponding change of the modified In Auger parameter is interpreted as being indicative of a change in the chemical environment of In as a function of Cu off-stoichiometry.}, language = {en} } @misc{HofmannYuFolseetal., author = {Hofmann, Timo and Yu, Ted H. and Folse, Michael and Weinhardt, Lothar and B{\"a}r, Marcus and Zhang, Yufeng and Merinov, Boris V. and Myers, Deborah J. and Goddard, William A. and Heske, Clemens}, title = {Reply to "Comment on 'Using Photoelectron Spectroscopy and Quantum Mechanics to Determine d-Band Energies of Metals for Catalytic Applications'"}, series = {Journal of Physical Chemistry : C}, volume = {117}, journal = {Journal of Physical Chemistry : C}, number = {13}, issn = {1932-7455}, pages = {6916 -- 6917}, language = {en} } @misc{BaerTheisenWilksetal., author = {B{\"a}r, Marcus and Theisen, J.-P. and Wilks, Regan G. and Erfurth, F. and Duarte, Roberto Felix and Gerlach, Dominic and Haas, S. and Tati-Bismaths, L. and Reinert, F. and Kronast, F. and Niesen, T. P. and Palm, J. and Visbeck, S. and Weinhardt, Lothar}, title = {Lateral inhomogeneity of the Mg/(Zn+Mg) composition at the (Zn,Mg)O/CuIn(S,Se)2 thin-film solar cell interface revealed by photoemission electron microscopy}, series = {Journal of Applied Physics}, volume = {113}, journal = {Journal of Applied Physics}, number = {19}, issn = {1520-8850}, doi = {10.1063/1.4804413}, pages = {193709}, abstract = {Spatial variations in the chemical composition of the (Zn,Mg)O/CuIn(S,Se)2 thin-film solar cell interface were studied by photoemission electron microscopy (PEEM). Energy filtered PEEM images indicate significant differences in the magnesium and zinc distribution. Local photoemission measurements reveal a relative difference in the derived Mg/(ZnþMg) composition of the (Zn,Mg)O material of up to (11.460.7)\%, which can be expected to induce band gap fluctuations of (60630) meV. Furthermore, local areas with significant accumulations of sodium could be observed.}, language = {en} } @misc{BaerKlaerWeinhardtetal., author = {B{\"a}r, Marcus and Klaer, Joachim and Weinhardt, Lothar and Wilks, Regan G. and Krause, Stefan and Blum, Monika and Yang, Wan Li and Heske, Clemens and Schock, Hans-Werner}, title = {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}, series = {Advanced Energy Materials}, volume = {3}, journal = {Advanced Energy Materials}, number = {6}, issn = {1614-6840}, pages = {777 -- 781}, abstract = {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.}, language = {en} } @misc{GorgoiGerlachWilksetal., author = {Gorgoi, Mihaela and Gerlach, Dominic and Wilks, Regan G. and Wippler, David and Wimmer, Manuel and Lozac'h, Micka{\"e}l and Duarte, Roberto Felix and M{\"u}ck, Leonie Anna and Meier, M. and Ueda, Shigenori and Yoshikawa, Hideki and Lips, Klaus and Rech, Bernd and Sumiya, Masatomo and H{\"u}pkes, J{\"u}rgen and Kobayashi, Kaoru and B{\"a}r, Marcus}, title = {The silicon/zinc oxide interface in amorphous silicon-based thin-film solar cells: Understanding an empirically optimized contact}, series = {Applied Physics Letters}, volume = {103}, journal = {Applied Physics Letters}, number = {2}, issn = {1077-3118}, pages = {023903}, abstract = {The electronic structure of the interface between the boron-doped oxygenated amorphous silicon "window layer" (a-SiOx:H(B)) and aluminum-doped zinc oxide (ZnO:Al) was investigated using hard x-ray photoelectron spectroscopy and compared to that of the boron-doped microcrystalline silicon (μc-Si:H(B))/ZnO:Al interface. The corresponding valence band offsets have been determined to be (-2.87 ± 0.27) eV and (-3.37 ± 0.27) eV, respectively. A lower tunnel junction barrier height at the μc-Si:H(B)/ZnO:Al interface compared to that at the a-SiOx:H(B)/ZnO:Al interface is found and linked to the higher device performances in cells where a μc-Si:H(B) buffer between the a-Si:H p-i-n absorber stack and the ZnO:Al contact is employed.}, language = {en} } @phdthesis{Gerlach, author = {Gerlach, Dominic}, title = {Surface and interface characterization of thin-film silicon solar cell structures}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-28254}, pages = {128}, language = {en} } @misc{PfrommerAzapiraSteigertetal., author = {Pfrommer, Johannes and Azapira, Anahita and Steigert, Alexander and Olech, Katarzyna and Menezes, Prashanth W. and Duarte, Roberto F{\´e}lix and Liao, Xiaxia and Wilks, Regan G. and B{\"a}r, Marcus and Schedel-Niedrig, Thomas and Driess, Matthias}, title = {Superiorly active and long-term stable nickel-based electrocatalysts for water oxidation in alkaline media based on the ZnO:Ni system}, series = {ChemCatChem}, volume = {9}, journal = {ChemCatChem}, number = {4}, issn = {1867-3899}, doi = {10.1002/cctc.201600922}, pages = {672 -- 676}, language = {en} } @misc{JeyachandranMeyerBenkertetal., author = {Jeyachandran, Y. L. and Meyer, Frank and Benkert, Andreas and B{\"a}r, Marcus and Blum, Monika and Yang, Wooyong and Reinert, Friedrich and Heske, Clemens and Weinhardt, Lothar and Zharnikov, Michael}, title = {Investigation of the ionic hydration in aqueous salt solutions by soft x‑ray emission spectroscopy}, series = {Journal of Physical Chemistry B: Condensed Matter, Materials, Surfaces, Interfaces \& Biophysical Chemistry}, volume = {120}, journal = {Journal of Physical Chemistry B: Condensed Matter, Materials, Surfaces, Interfaces \& Biophysical Chemistry}, number = {31}, issn = {1520-5207}, doi = {10.1021/acs.jpcb.6b03952}, pages = {7687 -- 7695}, language = {en} } @misc{WipplerWilksPietersetal., author = {Wippler, David and Wilks, Regan G. and Pieters, Bart E. and Albada, Sacha Jennifer van and Gerlach, Dominic and H{\"u}pkes, J{\"u}rgen and B{\"a}r, Marcus and Rau, Uwe}, title = {Pronounced surface band bending of thin-film silicon revealed by modeling core levels probed with hard x-rays}, series = {ACS Applied Materials \& Interfaces}, volume = {8}, journal = {ACS Applied Materials \& Interfaces}, number = {27}, issn = {1944-8252}, doi = {10.1021/acsami.6b04666}, pages = {17685 -- 17693}, language = {en} } @inproceedings{LipsSchulzeStarretal., author = {Lips, Klaus and Schulze, Tim F. and Starr, David E. and B{\"a}r, Marcus and Wilks, Regan G. and Fenske, F. and Ruske, Florian and Reiche, Martin and Krol, Roel van de and Reichardt, Gerd and Sch{\"a}fers, Franz and Hendel, Stefan and Follath, Rolf and Bahrdt, Johannes and Peredkov, Sergey and DeBeer, Serena and H{\"a}vecker, Michael and Knop-Gericke, Axel and Rau, Bj{\"o}rn and Kaufmann, Christian and Schlatmann, Rutger and Schl{\"o}gl, Robert and Rech, Bernd and Raoux, Simone}, title = {EMIL: The Energy Materials In-situ Laboratory Berlin - A novel characterization facility for photovoltaic and energy materials}, series = {31st European Photovoltaic Solar Energy Conference and Exhibition, proceedings of the international conference held in Hamburg, Germany, 14 -18 September 2015}, booktitle = {31st European Photovoltaic Solar Energy Conference and Exhibition, proceedings of the international conference held in Hamburg, Germany, 14 -18 September 2015}, publisher = {WIP}, address = {M{\"u}nchen}, isbn = {3-936338-39-6}, doi = {10.4229/EUPVSEC20152015-1AO.2.1}, pages = {25 -- 28}, language = {en} } @inproceedings{LipsStarrBaeretal., author = {Lips, Klaus and Starr, David E. and B{\"a}r, Marcus and Schulze, Tim F. and Fenske, F. and Christiansen, Silke and Krol, Roel van de and Raoux, Simone and Reichardt, Gerd and Sch{\"a}fers, Franz and Hendel, Stefan and Follath, Rolf and Bahrdt, Johannes and Scheer, M. and W{\"u}stefeld, Godehard and Kuske, P. and H{\"a}vecker, Michael and Knop-Gericke, Axel and Schl{\"o}gl, Robert and Rech, Bernd}, title = {EMIL: The Energy Materials In Situ Laboratory Berlin}, series = {40th Photovoltaic Specialists Conference (PVSC), 2014 : Colorado Convention Center, Denver, Colorado, 8-13 June 2014}, booktitle = {40th Photovoltaic Specialists Conference (PVSC), 2014 : Colorado Convention Center, Denver, Colorado, 8-13 June 2014}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4799-4398-2}, doi = {10.1109/PVSC.2014.6925017}, pages = {698 -- 700}, language = {en} } @misc{SmirnovLambertzMolletal., author = {Smirnov, V. and Lambertz, Andreas and Moll, S. and B{\"a}r, Marcus and Starr, David E. and Wilks, Regan G. and Gorgoi, Mihaela and Heidt, A. and Luysberg, Martina and Holl{\"a}nder, B. and Finger, F.}, title = {Doped microcrystalline silicon oxide alloys for silicon-based photovoltaics: Optoelectronic properties, chemical composition, and structure studied by advanced characterization techniques}, series = {Physica Status Solidi: A - Applications and Materials Science}, volume = {213}, journal = {Physica Status Solidi: A - Applications and Materials Science}, number = {7}, issn = {1862-6319}, doi = {10.1002/pssa.201533022}, pages = {1814 -- 1820}, language = {en} } @misc{ZangLinLietal., author = {Zang, Yufeng and Lin, Nanying and Li, Yaping and Wang, Xiadon and Kang, Junyong and Wilks, Regan G. and B{\"a}r, Marcus and Mu, Rui}, title = {The isotype ZnO/SiC heterojunction prepared by molecular beam epitaxy - A chemical inert interface with significant band discontinuities}, series = {Scientific reports}, volume = {6}, journal = {Scientific reports}, issn = {2045-2322}, doi = {10.1038/srep23106}, pages = {23106}, language = {en} } @misc{JaeckleLiebhaberNiederhausenetal., author = {J{\"a}ckle, Sara and Liebhaber, Martin and Niederhausen, Jens and B{\"u}chele, Matthias and Duarte, Roberto Felix and Wilks, Regan G. and B{\"a}r, Marcus and Lips, Klaus and Christiansen, Silke}, title = {Unveiling the Hybrid n-Si/PEDOT:PSS Interface}, series = {ACS Applied Materials \& Interfaces}, volume = {8}, journal = {ACS Applied Materials \& Interfaces}, number = {13}, issn = {1944-8244}, doi = {10.1021/acsami.6b01596}, pages = {8841 -- 8848}, language = {en} } @misc{BaerBarreauCouzinieDevyetal., author = {B{\"a}r, Marcus and Barreau, Nicolas and Couzini{\´e}-Devy, Fran{\c{c}}ois and Weinhardt, Lothar and Wilks, Regan G. and Kessler, John and Heske, Clemens}, title = {Impact of annealing-induced intermixing on the electronic level alignment at the In₂S₃/Cu(In,Ga)Se₂ thin-film solar cell interface}, series = {ACS Applied Materials \& Interfaces}, volume = {8}, journal = {ACS Applied Materials \& Interfaces}, number = {3}, issn = {1944-8244}, doi = {10.1021/acsami.5b10614}, pages = {2120 -- 2124}, language = {en} } @inproceedings{HandickReinhardWilksetal., author = {Handick, Evelyn and Reinhard, Patrick and Wilks, Regan G. and Pianezzi, Fabian and Duarte, Roberto Felix and Gorgoi, Mihaela and Kunze, Thomas and B{\"u}cheler, Stephan and Tiwari, Ayodhya N. and B{\"a}r, Marcus}, title = {NaF/KF post-deposition treatments and their influence on the structure of Cu(In,Ga)Se₂ absorber surfaces}, series = {IEEE 43rd Photovoltaic Specialists Conference (PVSC), 5-10 June 2016}, booktitle = {IEEE 43rd Photovoltaic Specialists Conference (PVSC), 5-10 June 2016}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-2724-8}, doi = {10.1109/PVSC.2016.7749400}, pages = {17 -- 21}, language = {en} } @misc{DuncanKephartHorsleyetal., author = {Duncan, Douglas A. and Kephart, Jason M. and Horsley, Kimberly and Blum, Monika and Mezher, Michelle and Weinhardt, Lothar and H{\"a}ming, Marc and Wilks, Regan G. and Hofmann, Timo and Yang, Wanli and B{\"a}r, Marcus and Sampath, Walajabad S. and Heske, Clemens}, title = {Characterization of sulfur bonding in CdS:O buffer layers for CdTe-based thin-film solar cells}, series = {ACS Applied Materials \& Interfaces}, volume = {7}, journal = {ACS Applied Materials \& Interfaces}, number = {30}, issn = {1944-8244}, doi = {10.1021/acsami.5b03503}, pages = {16382 -- 16386}, language = {en} } @misc{SadoughiStarrHandicketal., author = {Sadoughi, Golnaz and Starr, David E. and Handick, Evelyn and Stranks, Samuel D. and Gorgoi, Mihaela and Wilks, Regan G. and B{\"a}r, Marcus and Snaith, Henry J.}, title = {Observation and mediation of the presence of metallic lead in organic-inorganic perovskite films}, series = {ACS Applied Materials \& Interfaces}, volume = {7}, journal = {ACS Applied Materials \& Interfaces}, number = {24}, issn = {1944-8244}, doi = {10.1021/acsami.5b02237}, pages = {13440 -- 13444}, language = {en} } @misc{HauschildMeyerBenkertetal., author = {Hauschild, Dirk and Meyer, Frank and Benkert, Andreas and Kreikemeyer-Lorenzo, Dagmar and Pohlner, Stephan and Palm, J{\"o}rg and Blum, Monika and Yang, Wanli and Wilks, Regan G. and B{\"a}r, Marcus and Heske, Clemens and Weinhardt, Lothar and Reinert, Friedrich}, title = {Annealing-induced effects on the chemical structure of the In₂S₃/CuIn(S,Se)₂ thin-film solar cell interface}, series = {The Journal of Physical Chemistry: C, Nanomaterials and interfaces}, volume = {119}, journal = {The Journal of Physical Chemistry: C, Nanomaterials and interfaces}, number = {19}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.5b01622}, pages = {10412 -- 10416}, language = {en} } @misc{StarrSadoughiHandicketal., author = {Starr, David E. and Sadoughi, Golnaz and Handick, Evelyn and Wilks, Regan G. and Alsmeier, Jan Hendrik and K{\"o}hler, Leonard and Gorgoi, Mihaela and Snaith, Henry J. and B{\"a}r, Marcus}, title = {Direct observation of an inhomogeneous chlorine distribution in CH3NH3PbI3-xClx layers: surface depletion and interface enrichment}, series = {Energy \& Environmental Science}, volume = {8}, journal = {Energy \& Environmental Science}, number = {5}, issn = {1754-5692}, doi = {10.1039/C5EE00403A}, pages = {1609 -- 1615}, language = {en} } @misc{HagesLevcencoMiskinetal., author = {Hages, Charles J. and Levcenco, Sergej and Miskin, Caleb K. and Alsmeier, Jan Hendrik and Abou-Ras, Daniel and Wilks, Regan G. and B{\"a}r, Marcus and Unold, Thomas and Agrawal, Rakesh}, title = {Improved performance of Ge-alloyed CZTGeSSe thin-film solar cells through control of elemental losses}, series = {Progress in Photovoltaics: Research and Applications}, volume = {23}, journal = {Progress in Photovoltaics: Research and Applications}, number = {3}, issn = {1099-159X}, doi = {10.1002/pip.2442}, pages = {376 -- 384}, language = {en} } @phdthesis{Xiao, author = {Xiao, Ting}, title = {X-ray Spectroscopic Study of Heterostructure Contacting Schemes for Optoelectronic Devices}, address = {Cottbus}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-49391}, pages = {167}, language = {en} } @misc{MuSteigertLinetal., author = {Mu, Rui and Steigert, Alexander and Lin, Nanying and Wilks, Regan G. and B{\"a}r, Marcus and Zhang, Yufeng}, title = {The chemical structure of the ZnO/SiC heterointerface as revealed by electron spectroscopies}, series = {Journal of Physics D: Applied Physics}, volume = {48}, journal = {Journal of Physics D: Applied Physics}, number = {30}, issn = {1361-6463}, doi = {10.1088/0022-3727/48/30/305304}, pages = {305304}, language = {en} } @inproceedings{RepinsMansfieldKanevceetal., author = {Repins, Ingrid and Mansfield, Lorelle M. and Kanevce, Ana and Jensen, Soren A. and Kuciauskas, Darius and Glynn, Stephen and Barnes, Teresa and Metzger, Wyatt and Burst, James and Jiang, Chun-Sheng and Harvey, Steve and Dippo, Patricia and Teeter, Glenn and Perkins, C. and Egaas, Brian and Zakutayev, Andriy and Alsmeier, Jan Hendrik and Lußky, Thomas and Korte, Lars and Wilks, Regan G. and B{\"a}r, Marcus and Yan, Yanfa and Lany, Stephan and Zawadzki, Pawel and Zawadzki, Pawel and Park, Ji-Sang and Wei, Suhuai}, title = {Wild band edges: The role of bandgap grading and band-edge fluctuations in high-efficiency chalcogenide devices}, series = {2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), Portland, OR, USA, June 5-10, 2016}, booktitle = {2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), Portland, OR, USA, June 5-10, 2016}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-5090-2724-8}, pages = {309 -- 314}, language = {en} } @inproceedings{BaerStarrLambertzetal., author = {B{\"a}r, Marcus and Starr, David E. and Lambertz, Andreas and Holl{\"a}nder, B. and Alsmeier, Jan Hendrik and Weinhardt, Lothar and Blum, Mia and Gorgoi, Mihaela and Yang, Wooyong and Wilks, Regan G. and Heske, Clemens}, title = {Microcrystalline silicon oxides for silicon-based solar cells: Impact of the O/Si ratio on the electronic structure}, series = {Thin films for solar and energy technology VI : 17, 18 and 20 August 2014, San Diego, California, United States}, booktitle = {Thin films for solar and energy technology VI : 17, 18 and 20 August 2014, San Diego, California, United States}, editor = {Eldada, Louay A. and Heben, Michael J.}, publisher = {SPIE}, address = {Bellingham, Wash.}, isbn = {978-1-62841-204-8}, doi = {10.1117/12.2061902}, language = {en} } @misc{SullivanWilksWinkleretal., author = {Sullivan, J. T. and Wilks, Regan G. and Winkler, M. T. and Weinhardt, Lothar and Recht, D. and Said, A. J. and Newman, B. K. and Zhang, Y. and Blum, Monika and Krause, S. and Yang, Wan Li and Heske, Clemens and Aziz, M. J. and B{\"a}r, Marcus and Buonassisi, T.}, title = {Soft x-ray emission spectroscopy studies of the electronic structure of silicon supersaturated with sulfur}, abstract = {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.}, language = {en} } @misc{HofmannYuFolseetal., author = {Hofmann, Timo and Yu, Ted H. and Folse, Michael and Weinhardt, Lothar and B{\"a}r, Marcus and Zhang, Yufeng and Merinov, Boris V. and Myers, Deborah J. and Goddard, William A. and Heske, Clemens}, title = {Using Photoelectron Spectroscopy and Quantum Mechanics to Determine d‑Band Energies of Metals for Catalytic Applications}, series = {The Journal of Physical Chemistry : C}, volume = {116}, journal = {The Journal of Physical Chemistry : C}, number = {45}, issn = {1932-7455}, pages = {24016 -- 24026}, abstract = {The valence band structures (VBS) of eight transition metals (Fe, Co, Ni, Cu, Pd, Ag, Pt, Au) were investigated by photoelectron spectroscopy (PES) using He I, He II, and monochromatized Al Kα excitation. The influence of final states, photoionization cross-section, and adsorption of residual gas molecules in an ultrahigh vacuum environment are discussed in terms of their impact on the VBS. We find that VBSs recorded with monochromatized Al Kα radiation are most closely comparable to the ground state density of states (DOS) derived from quantum mechanics calculations. We use the Al Kα-excited PES measurements to correct the energy scale of the calculated ground-state DOS to approximate the "true" ground-state d-band structure. Finally, we use this data to test the d-band center model commonly used to predict the electronicproperty/ catalytic-activity relationship of metals. We find that a simple continuous dependence of activity on d-band center position is not supported by our results (both experimentally and computationally).}, language = {en} } @misc{BaerSchubertMarsenetal., author = {B{\"a}r, Marcus and Schubert, Bj{\"o}rn-Arvid and Marsen, Bj{\"o}rn and Krause, Stefan and Pookpanratana, Sujitra and Unold, Thomas and Weinhardt, Lothar and Heske, Clemens and Schock, Hans-Werner}, title = {Impact of KCN etching on the chemical and electronic surface structure of Cu2ZnSnS4 thin-film solar cell absorbers}, abstract = {The chemical and electronic surface structure of Cu2ZnSnS4 thin-film solar cell absorbers has been investigated by direct and inverse photoemission. Particular emphasis was placed on the impact of KCN etching, which significantly alters the surface composition and is best explained by a preferred etching of Cu and, to a lesser degree, Sn. As a consequence the surface band gap increased from (1.53 +/- 0.15) eV, which agrees with optically derived bulk band gap values, to (1.91 +/- 0.15) ev.}, language = {en} } @misc{BaerCouzinieDevyDuarteetal., author = {B{\"a}r, Marcus and Couzini{\`e}-Devy, Fran{\c{c}}ois and Duarte, Roberto Felix and Klaer, Joachim and Pookpanratana, Sujitra and Blum, Monika and Zhang, Yi and Denlinger, Jonathan D. and Yang, Wanli and Wilks, Regan G. and Weinhardt, Lothar and Schock, Hans-Werner and Southerland Kessler, Jude and Heske, Clemens}, title = {The Heavily Intermixed In2S3/Cu(In,Ga)Se2 Interface as Revealed by Photoelectron and Soft X-ray Emission Spectroscopy}, series = {2013 IEEE 39th Photovoltaic Specialists Conference, (PVSC 2013), Tampa, Florida, USA, 16 - 21 June 2013}, journal = {2013 IEEE 39th Photovoltaic Specialists Conference, (PVSC 2013), Tampa, Florida, USA, 16 - 21 June 2013}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-4799-3300-6}, doi = {10.1109/PVSC.2013.6744280}, pages = {857 -- 862}, language = {en} } @misc{ErikssonHahlinAxnandaetal., author = {Eriksson, Susanna K. and Hahlin, Maria and Axnanda, Stephanus and Crumlin, Ethan J. and Wilks, Regan G. and Odelius, Michael and Eriksson, Anna I. K. and Liu, Zhi and {\AA}hlund, John and Hagfeldt, Anders and Starr, David E. and B{\"a}r, Marcus and Rensmo, H{\aa}kan and Siegbahn, Hans}, title = {In-situ probing of H₂O effects on a Ru-complex adsorbed on TiO₂ using ambient pressure photoelectron spectroscopy}, series = {Topics in Catalysis}, volume = {59}, journal = {Topics in Catalysis}, number = {5}, issn = {1022-5528}, doi = {10.1007/s11244-015-0533-3}, pages = {583 -- 590}, language = {en} } @misc{HandickReinhardAlsmeieretal., author = {Handick, Evelyn and Reinhard, Patrick and Alsmeier, Jan Hendrik and K{\"o}hler, Leonard and Pianezzi, Fabian and Krause, Stefan and Gorgoi, Mihaela and Ikenaga, Eiji and Koch, Norbert and Wilks, Regan G. and B{\"u}cheler, Stephan and Tiwari, Ayodhya N. and B{\"a}hr, Marcus}, title = {Potassium postdeposition treatment-induced band gap widening at Cu(In,Ga)Se₂ surfaces - Reason for performance leap?}, series = {ACS Applied Materials \& Interfaces}, volume = {7}, journal = {ACS Applied Materials \& Interfaces}, number = {49}, issn = {1944-8244}, doi = {10.1021/acsami.5b09231}, pages = {27414 -- 27420}, language = {en} } @misc{MezherGarrisMansfieldetal., author = {Mezher, Michelle and Garris, Rebekah and Mansfield, Lorelle M. and Horsley, Kimberly and Weinhardt, Lothar and Duncan, Douglas A. and Blum, Monika and Rosenberg, Samantha G. and B{\"a}r, Marcus and Ramanathan, Kannan and Heske, Clemens}, title = {Electronic structure of the Zn(O,S)/Cu(In,Ga)Se₂ thin-film solar cell interface}, series = {Progress in Photovoltaics: Research and Applications}, volume = {24}, journal = {Progress in Photovoltaics: Research and Applications}, number = {8}, issn = {1099-159X}, doi = {10.1002/pip.2764}, pages = {1142 -- 1148}, language = {en} } @misc{WeinhardtErtanIannuzzietal., author = {Weinhardt, Lothar and Ertan, Emelie and Iannuzzi, Marcella and Weigand, Markus and Fuchs, Oliver and B{\"a}r, Marcus and Blum, Monika and Denlinger, Jonathan D. and Yang, Wooyong and Umbach, Eberhard and Odelius, Michael and Heske, Clemens}, title = {Probing hydrogen bonding orbitals: resonant inelastic soft X-ray scattering of aqueous NH₃}, series = {Physical Chemistry Chemical Physics}, volume = {17}, journal = {Physical Chemistry Chemical Physics}, number = {40}, issn = {1463-9084}, doi = {10.1039/C5CP04898B}, pages = {27145 -- 27153}, language = {en} } @misc{BenkertMeyerHauschildetal., author = {Benkert, Andreas and Meyer, Frank and Hauschild, Dirk and Blum, Monika and Yang, Wooyong and Wilks, Regan G. and B{\"a}r, Marcus and Reinert, Friedrich and Heske, Clemens and Weinhardt, Lothar}, title = {Isotope Effects in the Resonant Inelastic Soft X-ray Scattering Maps of Gas-Phase Methanol}, series = {The Journal of Physical Chemistry: A}, volume = {120}, journal = {The Journal of Physical Chemistry: A}, number = {14}, issn = {1089-5639}, doi = {10.1021/acs.jpca.6b02636}, pages = {2260 -- 2267}, language = {en} } @misc{MezherGarrisMansfieldetal., author = {Mezher, Michelle and Garris, Rebekah and Mansfield, Lorelle M. and Blum, Monika and Hauschild, Dirk and Horsley, Kimberly and Duncan, Douglas A. and Yang, Wooyong and B{\"a}r, Marcus and Weinhardt, Lothar and Ramanathan, Kannan and Heske, Clemens}, title = {Soft x-ray spectroscopy of a complex heterojunction in high-efficiency thin-film photovoltaics: Intermixing and Zn speciation at the Zn(O,S)/Cu(In,Ga)Se2 interface}, series = {ACS Applied Materials \& Interfaces}, volume = {8}, journal = {ACS Applied Materials \& Interfaces}, number = {48}, issn = {1944-8244}, doi = {10.1021/acsami.6b09245}, pages = {33256 -- 33263}, language = {en} } @misc{CaoJaftaGongetal., author = {Cao, Jie and Jafta, Charl J. and Gong, Jiang and Ran, Qidi and Lin, Xianzhong and Duarte, Roberto Felix and Wilks, Regan G. and B{\"a}r, Marcus and Yuan, Jiayin and Ballauff, Matthias and Lu, Yan}, title = {Synthesis of Dispersible Mesoporous Nitrogen-Doped Hollow Carbon Nanoplates with Uniform Hexagonal Morphologies for Supercapacitors}, series = {ACS Applied Materials \& Interfaces}, volume = {8}, journal = {ACS Applied Materials \& Interfaces}, number = {43}, issn = {1944-8244}, doi = {10.1021/acsami.6b08946}, pages = {29628 -- 29636}, language = {de} } @misc{LiaoJeongWilksetal., author = {Liao, Xiaxia and Jeong, Ahreum and Wilks, Regan G. and Wiesner, Sven and Rusu, Marin and B{\"a}r, Marcus}, title = {X-ray irradiation induced effects on the chemical and electronic properties of MoO3 thin films}, series = {Journal of Electron Spectroscopy and Related Phenomena}, volume = {212}, journal = {Journal of Electron Spectroscopy and Related Phenomena}, issn = {0368-2048}, doi = {10.1016/j.elspec.2016.08.004}, pages = {50 -- 55}, language = {en} } @misc{WeinhardtFuchsFischeretal., author = {Weinhardt, Lothar and Fuchs, Oliver and Fischer, Andr{\´e} and Weigand, Markus and Meyer, Frank and Benkert, Andreas and Blum, Monika and B{\"a}r, Marcus and Pookpanratana, Sujitra and Denlinger, Jonathan D. and Heske, Clemens and Umbach, Eberhard}, title = {Site- and Symmetry-resolved Resonant X-ray Emission Study of a Highly-ordered PTCDA Thin Film}, series = {The Journal of Physical Chemistry: C}, volume = {120}, journal = {The Journal of Physical Chemistry: C}, number = {16}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.5b12422}, pages = {8607 -- 8615}, language = {en} }