Dirk Hauschild

Dirk Hauschild
Karlsruhe Institute of Technology | KIT ·  Institute for Photon Science and Synchrotron Radiation

Dr.

About

47
Publications
7,315
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914
Citations
Citations since 2017
33 Research Items
849 Citations
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2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200

Publications

Publications (47)
Article
Full-text available
The electronic structures of four precursors for organic–inorganic hybrid perovskites, namely, methylammonium chloride and iodide, as well as formamidinium bromide and iodide, are investigated by X-ray emission (XE) spectroscopy at the carbon and nitrogen K-edges. The XE spectra are analyzed based on density functional theory calculations. We simul...
Article
2D/3D perovskite heterostructures have emerged as a promising material composition to reduce nonradiative recombination in perovskite-based LEDs and solar cells. Such heterostructures can be created by a surface treatment with large organic cations, for example, n-butylammonium bromide (BABr). To understand the impact of the BABr surface treatment...
Article
The substrate temperature TPDT during the alkali fluoride post-deposition treatment (PDT) of Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorbers is a critical process parameter. So far, TPDT is optimized empirically for a particular alkali distribution, and literature only reports on the effects of high TPDT (300 – 350°C). To better understand the...
Article
Full-text available
Narrow-band gap (NBG) Sn–Pb perovskites with band gaps of ∼1.2 eV, which correspond to a broad photon absorption range up to ∼1033 nm, are highly promising candidates for bottom solar cells in all-perovskite tandem photovoltaics. To exploit their potential, avoiding optical losses in the top layer stacks of the tandem configuration is essential. Th...
Article
An efficient surface defect passivation is observed by reacting clean Si in a dilute hydrogen sulfide-argon gas mixture (< 5% H2S in Ar) for both n-type and p-type Si wafers with planar and textured surfaces. Surface recombination velocities of 1.5 and 8 cm/s are achieved on n-type and p-type Si wafers, respectively, at an optimum reaction temperat...
Article
The chemical and electronic structures of 15 different sulfates are studied using S L2,3 soft X-ray emission spectroscopy (XES). Sulfur L2,3 XES spectra of sulfates are distinctively different from those of other sulfur compounds, which makes XES a powerful technique for sulfate detection. Furthermore, subtle but distinct differences between the sp...
Article
The organic component (methylammonium) of CH3NH3PbI3-xCl x -based perovskites shows electronic hybridization with the inorganic framework via H-bonding between N and I sites. Femtosecond dynamics induced by core excitation are shown to strongly influence the measured X-ray emission spectra and the resonant inelastic soft X-ray scattering of the org...
Article
The carbon-rich layer at the back-contact interface of a solution-processed Cu $_{2}$ ZnSn(S,Se) $_{4}$ (CZTSSe) absorber is investigated with a combination of surface-sensitive X-ray photoelectron and bulk-sensitive X-ray emission spectroscopy. For absorber deposition, an aqueous ammonium-thioglycolate (ATGL) solution was used, and the “buried”...
Article
Full-text available
X-SPEC is a high-flux spectroscopy beamline at the KIT (Karlsruhe Institute of Technology) Synchrotron for electron and X-ray spectroscopy featuring a wide photon energy range. The beamline is equipped with a permanent magnet undulator with two magnetic structures of different period lengths, a focusing variable-line-space plane-grating monochromat...
Article
Full-text available
This article demonstrates a flash-type kinetic sulfurization method to introduce band-gap grading in CZTSe based photovoltaic devices. The developed approach allows to achieve a steep grading profile on kesterite thin-film surface.
Article
Dry buffer layer deposition techniques for chalcopyrite (CIGSSe)-based thin-film solar cells lack the surface-cleaning characteristics of the commonly used CdS or Zn(O,S) wet-chemical bath deposition. A UV-induced ozone and/or a low-energy Ar+-ion treatment could provide dry CIGSSe surface cleaning steps. To study the impact of these treatments, th...
Article
The nitrogen K-edge resonant inelastic x-ray scattering (RIXS) map of nitric oxide (NO) has been measured and simulated to provide a detailed analysis of the observed features. High-resolution experimental RIXS maps were collected using an in situ gas flow cell and a high-transmission soft x-ray spectrometer. Accurate descriptions of the ground, ex...
Article
To replace the conventionally used CdS buffers in Cu2ZnSn(S,Se)4 (CZTSSe) based thin-film solar cells, sputtered Zn(O,S) buffer layers have been investigated. Zn(O,S) layers with three different [O]/([O] + [S]) ratios (0.4, 0.7, and 0.8)—and a combination of Zn(O,S) and CdS (“hybrid buffer layer”) were studied. In comparison to the CdS reference, t...
Cover Page
All-perovskite multijunction photovoltaics, combining a wide-bandgap (WBG) perovskite top solar cell (EG ≈ 1.6–1.8 eV) with a low-bandgap (LBG) perovskite bottom solar cell (EG < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite sola...
Article
Full-text available
All‐perovskite multijunction photovoltaics, combining a wide‐bandgap (WBG) perovskite top solar cell (EG ≈1.6–1.8 eV) with a low‐bandgap (LBG) perovskite bottom solar cell (EG < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar...
Article
Full-text available
Synchrotron experiments combining real-time stress, X-ray diffraction, and X-ray reflectivity measurements, complemented by in situ electron diffraction and photon electron spectroscopy measurements, revealed a detailed picture of the interfacial silicide formation during deposition of ultrathin Pd layers on amorphous silicon. Initially, an amorpho...
Article
Full-text available
Thin‐film solar cells have great potential to overtake the currently dominant silicon‐based solar cell technologies in a strongly growing market. Such thin‐film devices consist of a multilayer structure, for which charge‐carrier transport across interfaces plays a crucial role in minimizing the associated recombination losses and achieving high sol...
Cover Page
In article number 1803699, Ulrich W. Paetzold and co‐workers develop a novel 2D Ruddlesden–Popper perovskite interlayer by solution processing n‐butylammonium bromide on wide‐bandgap double‐cation perovskite absorber layers (EG ≈ 1.72 eV). The devices with this 2D/3D heterostructure induce a high open‐circuit voltage of up to 1.31 V, which leads to...
Article
Full-text available
The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft x-ray emission spectroscopy (XES), resonant inelastic soft x-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the pepti...
Article
We report on the chemical and electronic structure of the interface between a thermally co-evaporated InxSy buffer and a Cu2ZnSn(S,Se)4 (CZTSSe) absorber for thin-film solar cells that, to date, has achieved energy conversion efficiencies up to 8.6 %. Using surface-sensitive x-ray and UV photoelectron spectroscopy, combined with inverse photoemissi...
Article
In this work, the authors realize stable and highly efficient wide‐bandgap perovskite solar cells that promise high power conversion efficiencies (PCE) and are likely to play a key role in next generation multi‐junction photovoltaics (PV). This work reports on wide‐bandgap (≈1.72 eV) perovskite solar cells exhibiting stable PCEs of up to 19.4% and...
Article
Full-text available
Cu2ZnSnS4(CZTS) thin‐film solar cell absorbers with different bandgaps can be produced by parameter variation during thermal treatments. Here, the effects of varied annealing time in a sulfur atmosphere and an ordering treatment of the absorber are compared. Chemical changes in the surface due to ordering are examined, and a downshift of the valenc...
Article
Full-text available
Molybdenum (Mo) is the most commonly used back-contact material for copper zinc tin selenide (CZTSe)-based thin-film solar cells. For most fabrication methods, an interfacial molybdenum diselenide (MoSe2) layer with an uncontrolled thickness is formed, ranging from a few tens of nm up to ≈1 μm. In order to improve the control of the back-contact in...
Article
We present a detailed characterization of the chemical structure of the Cu(In,Ga)Se2 thin-film surface and the CdS/Cu(In,Ga)Se2 interface, both with and without a RbF post-deposition treatment (RbF-PDT). For this purpose, x-ray photoelectron and Auger electron spectroscopy, as well as synchrotron-based soft x-ray emission spectroscopy have been emp...
Conference Paper
In the last decade, remarkable steps have been made to replace the traditionally used, wet‐chemical processed CdS buffer layer for Cu(In,Ga)(S,Se)2 (CIGSSe)‐based thin‐film solar cells by alternative materials. Among these alternatives, indium sulfide (InxSy) is a promising candidate for a “dry” in‐line buffer deposition process, and cell stacks us...
Article
The occupied and unoccupied electronic structure of imidazole (C3N2H4) and imidazolium (C3N2H5⁺) in aqueous solutions is studied by x-ray emission spectroscopy (XES) and resonant inelastic soft x-ray scattering (RIXS). Both systems show distinct RIXS fingerprints with strong resonant effects. A comparison with calculated x-ray emission spectra of i...
Article
Doping an indium sulfide buffer layer with sodium is a promising route to replace the “state‐of‐the‐art” CdS buffer layer in chalcopyrite‐based thin‐film solar cells, as it achieves efficiencies as high as 17.9% for large‐area devices (30 cm × 30 cm). We report on the chemical and electronic structure of the InxSy:Na/CuIn(S,Se)2 (CISSe) interface f...
Article
Recently, a world-record efficiency of 22.6 % was achieved by applying a RbF post-deposition treatment (PDT) on a Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorber surface. Here, we study the impact of this RbF-PDT on the electronic structure of the CIGSe surface and the CdS/CIGSe interface using ultraviolet and x-ray photoelectron spectroscopy (U...
Article
Non-resonant N K, O K, C K, and S L2,3 X-ray emission spectra (XES) of the 20 most common proteinogenic amino acids in their solid zwitterionic form are reported. They represent a comprehensive database, which can serve as a reliable basis for XES studies of peptides and proteins. At the most important N and O K-edges, clear similarities and differ...
Article
Full-text available
TiO2 nanoparticleshave been synthesized by the sol-gel method using titanium alkoxide and isopropanolas a precursor. The structural properties and chemical composition of the TiO2 nanoparticles were studied usingX-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The X-ray powder diffraction pattern confirms that...
Article
The chemical structure of the Zn(O,S)/Cu(In,Ga)Se2 interface in high-efficiency photovoltaic devices is investigated using x-ray photoelectron and Auger electron spectroscopy, as well as soft x-ray emission spectroscopy. We find that the Ga/(Ga+In) ratio at the absorber surface does not change with the formation of the Zn(O,S)/Cu(In,Ga)Se2 interfac...
Article
Using reflection electron energy loss spectroscopy (REELS), we have investigated the optical properties at the surface of a chalcopyrite-based Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar cell absorber, as well as an indium sulfide (InxSy) buffer layer before and after annealing. By fitting the characteristic inelastic scattering cross-section λK(E) t...
Article
The electronic structure of gas-phase methanol molecules (H3COH, H3COD, and D3COD) at atmospheric pressure has been investigated using resonant inelastic soft x-ray scattering (RIXS) at the O K and C K edges. We observe strong changes of the relative emission intensities of all valence orbitals as a function of excitation energy, which can be relat...
Thesis
In this thesis, thin-film solar cells on the basis of Cu(In,Ga)(S,Se)2 (CIGSSe) were investigated. Until today, most high efficient CIGSSe-based solar cells use a toxic and wetchemical deposited CdS buffer layer, which doesn’t allow a dry inline production. However, a promising and well-performing alternative buffer layer, namely indium sulfide, ha...
Article
We have investigated the impact of heat treatments on the chemical structure of the In2S3/CuIn(S,Se)2 thin-film solar cell interface using x-ray photoelectron and soft x-ray emission spectroscopy. As-grown, we find the formation of a sulfur-poor (indium-rich) In2S3 surface, an abrupt interface, and sulfur atoms in both In2S3 and CuIn(S,Se)2 chemica...
Article
The electronic structure of the amino acid L-cysteine in aqueous environment was studied using resonant inelastic soft x-ray scattering (RIXS) in a 2D map representation and analyzed in the framework of a "building block" approach. The element-selectivity of RIXS allows a local investigation of the electronic structure of the three functional group...
Article
Several experimental methods allow measuring the spatial probability density of electrons in atoms, molecules and solids, that is, the absolute square of the respective single-particle wave function. But it is an intrinsic problem of the measurement process that the information about the phase is generally lost during the experiment. The symmetry o...
Article
Environmentally driven aging effects play a crucial role in thin-film solar cells based on Cu(In,Ga)(S,Se)2, both for long-term stability and short air exposure during production. For a better understanding of such effects, Cu(In,Ga)(S,Se)2 absorber surfaces were investigated by x-ray photoelectron and Auger electron spectroscopy after exposure to...
Article
Ruthenium capped multilayer coatings for use in the extreme ultraviolet (EUV) radiation regime have manifold applications in science and industry. Although the Ru cap shall protect the reflecting multilayers, the surface of the heterostructures suffers from contamination issues and surface degradation. In order to get a better understanding of the...
Conference Paper
Poly(3-hexylthiophene): phenyl-[6,6]-C61 butyric acid methyl ester (P3HT:PCBM) bulk heterojunctions (BHJ) are prototype active layers for organic solar cells. The electronic structure at the internal interface can be accessed by photoelectron spectroscopy (PES), thus providing insight into the alignment of the electronic levels and the occurrence o...
Article
The properties of molecular films are determined by the geometric structure of the first layers near the interface. These are in contact with the substrate and feel the effect of the interfacial bonding, which particularly, for metal substrates, can be substantial. For the model system 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(110), the ge...

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