A5037047569- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Perovskite Materials and Applications
- Solid-state spectroscopy and crystallography
- Semiconductor materials and interfaces
- Electrocatalysts for Energy Conversion
- Silicon and Solar Cell Technologies
- CO2 Reduction Techniques and Catalysts
- solar cell performance optimization
- Hybrid Renewable Energy Systems
- Advanced Photocatalysis Techniques
- Fuel Cells and Related Materials
- Advanced battery technologies research
- Advanced Battery Technologies Research
- Electronic and Structural Properties of Oxides
- Ionic liquids properties and applications
- Molecular Junctions and Nanostructures
- Advancements in Battery Materials
- Advanced Semiconductor Detectors and Materials
- Thermal properties of materials
- ZnO doping and properties
- Optical properties and cooling technologies in crystalline materials
- Adsorption and Cooling Systems
- Luminescence Properties of Advanced Materials
Joint Center for Artificial Photosynthesis
2019-2025
Lawrence Berkeley National Laboratory
2019-2025
nLIGHT (United States)
2022-2025
University of Luxembourg
2016-2023
Technical University of Munich
2023
Czech Academy of Sciences, Institute of Physics
2023
University of Twente
2023
Luxembourg Institute of Science and Technology
2016-2018
Carl von Ossietzky Universität Oldenburg
2016
Postfabrication surface treatment strategies have been instrumental to the stability and performance improvements of halide perovskite photovoltaics in recent years. However, a consensus understanding complex reconstruction processes occurring at is still lacking. Here, we combined complementary surface-sensitive depth-resolved techniques investigate mechanistic microscale level. We observed toward more PbI2-rich top induced by commonly used solvent isopropyl alcohol (IPA). discuss several...
Bromide inclusion altered the formation dynamics and defect physics of wide-bandgap perovskite compositions.
Clean hydrogen production requires large-scale deployment of water-electrolysis technologies, particularly proton-exchange-membrane water electrolyzers (PEMWEs). However, as iridium-based electrocatalysts remain the only practical option for PEMWEs, their low abundance will become a bottleneck sustainable economy. Herein, we propose high-performing and durable ionomer-free porous transport electrodes (PTEs) with facile recycling features enabling Ir thrifting reclamation. The offer pathway...
Wide range of techniques used to obtain fundamental optical and optoelectronic properties CZTS single crystals grown by vapour transport.
Complex phenomena are prevalent during the formation of materials, which affect their processing-structure-function relationships. Thin films methylammonium lead iodide (CH3NH3PbI3, MAPI) processed by spin coating, antisolvent drop, and annealing colloidal precursors. The structure properties transient stable phases formed process reported, mechanistic insights underlying transitions revealed combining in situ data from grazing-incidence wide-angle X-ray scattering photoluminescence...
Proton-exchange membrane water electrolyzers (PEMWEs) are a promising technology for green hydrogen production; however, interfacial transport behaviors poorly understood, hindering device performance and longevity. Here, we first utilized finite-gap electrolyzer to demonstrate the possibility of proton transfer through in PEMWEs. The measured high-frequency resistances (HFRs) exhibit linear trend with increasing gap distance, where extrapolation shows lower value compared HFRs regular...
Electrochemical CO2 reduction (CO2R) using heterogenized molecular catalysts usually yields 2-electron products (CO, formate). Recently, it has been reported that certain preparations of immobilized cobalt phthalocyanine (CoPc) produce methanol (MeOH), a 6-electron product. Here, we demonstrate the significant role intermediate mass transport in CoPc selectivity to methanol. We first developed simple, physically mixed, polymer (and polyfluoroalkyl, PFAS)-free preparation on multiwalled...
Chalcopyrite materials, like CuInSe2 or Cu(In,Ga)Se2, are used as absorbers in thin film solar cells. The interest cells is based on the fact that they present a particularly low carbon footprint. However, much less known about electronic defects material compared to more common semiconductors. authors use mainly photoluminescence study defects. In this paper review experimental and theoretical defect studies arrive at comprehensive model. They show shallow defects, contribute free carriers,...
Abstract Halide perovskites have emerged as materials for high‐performance optoelectronic devices. Often, progress made to date in terms of higher efficiency and stability is based on increasing material complexity, i.e., formation multicomponent halide with multiple cations anions. In this review article, the use situ optical methods, namely, photoluminescence (PL) UV‐vis, that provide access relevant time length scales ascertain chemistry–property relationships by monitoring evolving...
This study explores the ionic dynamics in 2D/3D perovskite solar cells, which are known for their improved efficiency and stability. The focus is on impact of halide choice 3D perovskites treated with phenethylammonium salts (PEAX, X = Br I). Our findings reveal that light heat drive migration these structures, PEA+ species diffusing into film PEABr-treated samples. Mixed-halide show interdiffusion, bromine migrating to surface iodine film. Cathodoluminescence microscopy reveals localized 2D...
The quasi Fermi level splitting is measured for Cu(In,Ga)Se2 absorber layers with different copper to (indium + gallium) ratios and gallium contents in the range of 20%–40%. For absorbers a [Cu]/[In Ga] ratio below one, 120 meV higher compared grown under excess independent content, contrary ternary CuInSe2 where slightly excess. Possible explanations are gradient determined by secondary ion mass spectrometry measurement which less pronounced towards surface stoichiometric or fundamentally...
Abstract The electrical and optoelectronic properties of materials are determined by the chemical potentials their constituents. relative density point defects is thus controlled, allowing to craft microstructure, trap densities doping levels. Here, we show that chalcogenide near edge existence region not only during growth but also at room temperature post-processing. In particular, study generation anion vacancies, which critical in semiconductors topological insulators. example CuInSe 2...
Copper-tantalate, Cu2Ta4O11 (CTO), shows significant promise as an efficient photocathode for multi-carbon compounds (C2+) production through photoelectrochemical (PEC) CO2 reduction, owing to its suitable energy bands and catalytic surface. However, synthesizing CTO poses a challenge due metastable nature thermal instability. In this study, is addressed by employing flux-mediated synthesis technique using sodium-based flux create sodium-doped (Na-CTO) thin films, providing enhanced...
The absence of affordable and deployable large-scale energy storage poses a major barrier to providing zero-emission on demand for societal decarbonization. High temperature thermal is one promising option with low cost high scalability, but it hindered by the inherent complexity simultaneously satisfying all material requirements. Here we design class ceramic–carbon composites based co-optimizing mechanical, electrical, properties. These demonstrate stability in soak-and-hold tests direct...
Abstract This work presents a computational screening approach to identify Li‐rich transition‐metal oxide sacrificial cathode additives and provides experimental validation of antifluorite‐structured Li 6 MnO 4 as potential candidate. Initial attempts synthesize this compound result in low purity (≤40% by weight) owing close thermodynamic competition with 2 O at temperature. However, it is shown that much higher 85% weight can be achieved combining excess rapid cooling from high temperature,...
Abstract Fluorination has been identified as a key element for enabling the stable cycling of earth‐abundant manganese‐based disordered rock salt (DRX) cathodes. However, fluorination in DRX bulk remains challenge scalable solid‐state synthesis. In this study, tailored reaction pathway is proposed to synthesize highly fluorinated DRX. It demonstrated first time that unconventional precursors, Li 6 MnO 4 , MnF 2 and TiO can avoid formation Mn‐based intermediates (such (Mn,Ti)O 3, LiMnO Mn 3 O...
Accessing the electrode-electrolyte interface under operating conditions and capturing time-resolved kinetics challenge electrochemical studies. Copper’s interfacial oxidation dynamics remain unclear despite extensive research. Modulation excitation X-ray absorption spectroscopy (ME-XAS) probes...
Thin-film solar cells consist of several layers. The interfaces between these layers can provide critical recombination paths and consequently play a vital role in the efficiency cell. One main challenges for polycrystalline semiconductor absorber materials is absorber-buffer interface. $\mathrm{Cu}(\mathrm{In},\mathrm{Ga})\mathrm{S}{\mathrm{e}}_{2}$ system particularly interesting this context, since Cu-rich absorbers are dominated by at interface, while Cu-poor ones not. This paper unveils...
The antisolvent dripping time during spin-coating of CH3NH3PbI3 (MAPbI3) strongly impacts film morphology as well possible formation the intermediate precursor phase and—consequently—device performance. Here, we use in situ photoluminescence (PL) to directly monitor fast-occurring changes MAPbI3 synthesis. These measurements reveal how ideal timing leads homogeneous nucleation and pinhole-free films. In addition, these films show significantly reduced nonradiative recombination with 1.5...
Perovskite solar cells have received substantial attention due to their potential for low-cost photovoltaic devices on flexible or rigid substrates. Thiocyanate (SCN)-containing additives, such as MASCN (MA = methylammonium), been shown control perovskite film crystallization and the microstructure achieve effective room-temperature absorber processing. Nevertheless, pathways mechanisms of formation involved in additive processing are far from clear. Using situ X-ray diffraction...
Abstract Alkali metal doping and grain boundaries (GB) have been at the center of attention within Cu(In,Ga)(S,Se) 2 photovoltaics community for years. This study provides first experimental evidence that GB sodium‐doped CuInSe thin films may undertake reversible oxidation even room temperature, whereas undoped not. The findings are corroborated by cathodoluminescence imaging, secondary ion mass spectrometry, Kelvin probe force microscopy on air‐exposed subsequently subject to vacuum. A...
Abstract Thin film tandem solar cells provide a promising approach to achieve high efficiencies. These require at least bottom low bandgap and an upper cell. In this contribution, 2 high‐performance Cu(In,Ga)Se with bandgaps as 1.04 1.07 eV are presented. have shown certified efficiencies of 15.7% 16.6% respectively. Measuring these under 780‐nm longpass filter, corresponding the typical top cell in applications (1.57 eV), they achieved 7.9% 8.3%. Admittance measurements showed no...
The photoluminescence of a semiconductor is very sensitive means to determine its absorption coefficient $\ensuremath{\alpha}$, using Planck's generalized law. standard method (suitable only for self-supported thick samples like wafers) here extended multilayer thin films, by the transfer-matrix include effects substrate and optional front layers. This technique allows one circumvent parasitic from substrate, thus $\ensuremath{\alpha}$ accurately down low values, investigation deep band...
In the search for new materials solar cells, a fast feedback is needed. Radiative efficiency measurements based on photoluminescence (PL) are tool of choice to screen voltage material capable of. Additionally dependence radiative excitation density contains information diode ideality factor, which determines in turn fill factor cell. Both parameters immediate ingredients cell and can be determined from PL measurements, allow feedback. The method determine optical compare electrical finished...