A5044139020- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Copper-based nanomaterials and applications
- Silicon and Solar Cell Technologies
- Thin-Film Transistor Technologies
- Electron and X-Ray Spectroscopy Techniques
- Photovoltaic System Optimization Techniques
- Photonic and Optical Devices
- Integrated Circuits and Semiconductor Failure Analysis
- Plasmonic and Surface Plasmon Research
- Advancements in Battery Materials
- X-ray Spectroscopy and Fluorescence Analysis
- Machine Learning in Materials Science
- solar cell performance optimization
- Semiconductor materials and interfaces
- Nanowire Synthesis and Applications
- Advanced Battery Technologies Research
- Advanced Battery Materials and Technologies
University of Stuttgart
2016-2018
Helmholtz-Zentrum Berlin für Materialien und Energie
2009
Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute
2003-2008
Institut für Solarenergieforschung
2006
Abstract Recent progress in fabricating Cd‐ and Se‐free wide‐gap chalcopyrite thin‐film solar devices with Zn(S,O) buffer layers prepared by an alternative chemical bath process (CBD) using thiourea as complexing agent is discussed. has a larger band gap ( E g = 3·6–3·8 eV) than the conventional material CdS 2·4 currently used chalcopyrite‐based thin films cells. Thus, potential material, which already results Cd‐free cell increased spectral response blue wavelength region if low‐gap...
The application of Zn compounds as buffer layers was recently extended to wide-gap CuInS2 (CIS) based thin film solar cells. Using an alternative chemical deposition route for the preparation aiming at a single-layer, nominal ZnS without need any toxic reactants such hydrazine has helped us achieve similar efficiency respective CdS-buffered reference devices. In order shed light on differences other Zn-compound buffers deposited in conventional baths [chemical bath (CBD)] compared by this...
Electroluminescence (EL) is a powerful tool for the qualitative mapping of electronic properties solar modules, where and electrical defects are easily detected. However, direct quantitative prediction module performance purely based on electroluminescence images has yet to be accomplished. Our novel approach, called “EL power modules” (ELMO) as presented here, used just two predict loss mechanically damaged modules when compared their original (data sheet) power. First, using this method,...
Conventional electroluminescence characterization of photovoltaic modules relies on injecting current into the from external power sources. Our novel feedback modulator uses generated by module itself: We enable self-sourced under daylight conditions. The periodically collects solar generator, stores it, boosts it up to a higher voltage, and, finally, injects accumulated energy back generator; thus, provoking electroluminescence. As proof concept, we present images large area module.
Abstract Chalcopyrite thin film solar cells with an In 2 S 3 buffer showed high efficiencies above 15%, but only after annealing at 200 °C. One possible explanation is a Cu interdiffusion the absorber/buffer interface. We were able to directly measure new tool BESSY synchrotron facility: HIKE (high kinetic energy X‐ray photoelectron spectroscopy). Due its increased information depth of up 10–20 nm provide chemical even through closed overlayers. The endstation also allows in‐situ heating. A...
Metallic nanoantennas can be used to enhance the efficiency of optical device operation by re-distributing electromagnetic energy. Here, we investigate effect a random distribution disc-shaped Al different diameters deposited on Ge-on-Si PIN-photodetectors wavelength-dependent responsivity. We compare our experimental results simulations and find that largest responsivity enhancement is obtained for wavelengths correspond energies at or below bandgap energy Ge. argue this result...
The application of Zn compounds as buffer layers was recently extended to wide-gap CuInS2 (CIS) based thin-film solar cells. Using an alternative chemical deposition route for the preparation aiming at a single-layer, nominal ZnS without need any toxic reactants such hydrazine has helped us achieve similar efficiency respective CdS-buffered reference devices. After identifying deposited compound, ZnS∕Zn(S,O) bilayer in former investigations [M. Bär et al., J. Appl. Phys. 99, 123503 (2006)],...
A novel variant of the ion layer gas reaction (ILGAR) process is described. Up to now, only layers with a maximum thickness about 100 nm could be deposited by ILGAR in reasonable time. Replacing dipping spraying on warm substrate accelerated application precursor solution (e.g., metal chloride water) factor at least 100. For multinary products, all precursors are applied either simultaneously as mixed or sequentially. In intervals, stopped and H2S allowed flow over substrate. special, yet...
Bridging the gap between high-vacuum soft X-ray absorption spectroscopy and real systems under ambient conditions probes chemical reactions in situ during deposition annealing processes. The origin of highly efficient buffer layers Zn(S,O) is complex formation Zn(2+) S=C group thiourea (see schematic), which allows ligand-to-metal metal-to-ligand charge transfer (LMCT MLCT).
Abstract Progress in fabricating Cu(In,Ga)(S,Se) 2 (CIGSSe) solar cells with Zn(S,O) buffer layers prepared by chemical bath deposition (CBD) is discussed. The effect of different Zn salt precursors on cell device performance investigated using production scale CIGSSe absorbers provided AVANCIS GmbH & Co. KG. CBD process has been developed at the Hahn‐Meitner‐Institut (HMI) zinc nitrate, sulphate or chloride as precursor. An average efficiency 14.2 ± 0.8% obtained one‐layer dominant...
Constraining lithium-ion cells increases the cyclic lifetime. However, depending on an expected volume expansion during charge and discharge cycling, defining optimal constraining pressure range is not straightforward. In this study, we investigate a lithium iron phosphate/graphite pouch cell at four initial levels. As function of C-Rate, thermodynamic principle non-monotonic curve full cycles evaluated. Using rubber balloon model to calculate chemical potential phosphate discussing...
We present a straightforward self-scaling imaging technique to extract the effective minority carrier lifetime image of silicon solar cells using periodically modulated electroluminescence. This novel modulation overcomes main limiting factors linked camera integration time. Our approach is based on comparing three luminescence images taken during current modulation. One while injecting excess charge carriers with pulsed stimulation followed by an open-circuit decay. A second same injection...