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See detailMetastable Defects Decrease the Fill Factor of Solar Cells
Weiss, Thomas UL; Ramirez Sanchez, Omar UL; Paetel, Stefan et al

in Physical Review Applied (2023)

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See detailChalcopyrite solar cells - state-of-the-art and options for improvement
Siebentritt, Susanne UL; Weiss, Thomas UL

in Science China: Physics, Mechanics and Astronomy (2022)

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See detailSn4+-free, stable tin perovskite films for lead-free perovskite solar cells
Singh, Ajay UL; Hieulle, Jeremy UL; Phirke, Himanshu UL et al

in 2022 IEEE 49th Photovoltaics Specialists Conference (PVSC) (2022, November 14)

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See detailPhotoluminescence assessment of materials for solar cell absorbers
Siebentritt, Susanne UL; Rau, Uwe; Gharabeiki, Sevan UL et al

in Faraday Discussions (2022)

Absolute photoluminescence measurements present a tool to predict the quality of photovoltaic absorber materials before finishing the solar cells. Quasi Fermi level splitting predicts the maximal open ... [more ▼]

Absolute photoluminescence measurements present a tool to predict the quality of photovoltaic absorber materials before finishing the solar cells. Quasi Fermi level splitting predicts the maximal open circuit voltage. However, various methods to extract quasi Fermi level splitting are plagued by systematic errors in the range of 10–20 meV. It is important to differentiate between the radiative loss and the shift of the emission maximum. They are not the same and when using the emission maximum as the “radiative” band gap to extract the quasi Fermi level splitting from the radiative efficiency, the quasi Fermi level splitting is 10 to 40 meV too low for a typical broadening of the emission spectrum. However, radiative efficiency presents an ideal tool to compare different materials without determining the quasi Fermi level splitting. For comparison with the open circuit voltage, a fit of the high energy slope to generalised Planck’s law gives more reliable results if the fitted temperature, i.e. the slope of the high energy part, is close to the actual measurement temperature. Generalised Planck’s law also allows the extraction of a non-absolute absorptance spectrum, which enables a comparison between the emission maximum energy and the absorption edge. We discuss the errors and the indications when they are negligible and when not. [less ▲]

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See detailIndium-free CIGS analogues: general discussion
Dale, Phillip UL; Siebentritt, Susanne UL; Sood, Mohit UL et al

in Faraday Discussions (2022)

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See detailSulfide Chalcopyrite Solar Cells–Are They the Same as Selenides with a Wider Bandgap?
Siebentritt, Susanne UL; Lomuscio, Alberto UL; Adeleye, Damilola UL et al

in Physica Status Solidi. Rapid Research Letters (2022), 2200126

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See detailBulk and surface characterisation techniques of solar absorbers: general discussion
Dale, Phillip UL; Siebentritt, Susanne UL; sood et al

in Faraday Discussions (2022)

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See detailDiode Factor in Solar Cells with Metastable Defects and Back Contact Recombination
Wang, Taowen UL; Ehre, Florian UL; Weiss, Thomas UL et al

in Advanced Energy Materials (2022)

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See detailComprehensive physicochemical and photovoltaic analysis of different Zn substitutes (Mn, mg, Fe, Ni, Co, Ba, Sr) in CZTS-inspired thin film solar cells.
Lie, Stener; Guc, Maxim; Tunuguntla, Venkatesh et al

in Journal of Materials Chemistry (2022)

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See detailOrigin of Interface Limitation in Zn(O,S)/CuInS2‑Based Solar Cells
Sood, Mohit UL; Bombsch, Jakob; Lomuscio, Alberto UL et al

in ACS Applied Materials and Interfaces (2022), 14

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See detailHigh-resolution XEOL spectroscopy setup at the X-ray absorption spectroscopy beamline P65 of PETRA III
Levcenko, S.; Biller, B.; Pfeiffelmann, P. et al

in Journal of Synchrotron Radiation (2022), 29

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See detailDirect Probing of Gap States and Their Passivation in Halide Perovskites by High-Sensitivity, Variable Energy Ultraviolet Photoelectron Spectroscopy
Igal, Levine; Kohei, Shimizu; Lomuscio, Alberto UL et al

in Journal of Physical Chemistry. C, Nanomaterials and interfaces (2022), 125

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See detailNear surface defects: Cause of deficit between internal and external open-circuit voltage in solar cells
Sood, Mohit UL; Urbanaik, Aleksander; Kameni Boumenou, Christian UL et al

in Progress in Photovoltaics (2021)

Interface recombination in a complex multilayered thin-film solar structure causes a disparity between the internal open-circuit voltage (VOC,in), measured by photoluminescence, and the external open ... [more ▼]

Interface recombination in a complex multilayered thin-film solar structure causes a disparity between the internal open-circuit voltage (VOC,in), measured by photoluminescence, and the external open-circuit voltage (VOC,ex), that is, a VOC deficit. Aspirations to reach higher VOC,ex values require a comprehensive knowledge of the connection between VOC deficit and interface recombination. Here, a near-surface defect model is developed for copper indium di-selenide solar cells grown under Cu-excess conditions. These cell show the typical signatures of interface recombination: a strong disparity between VOC,in and VOC,ex, and extrapolation of the temperature dependent q·VOC,ex to a value below the bandgap energy. Yet, these cells do not suffer from reduced interface bandgap or from Fermi-level pinning. The model presented is based on experimental analysis of admittance and deep-level transient spectroscopy, which show the signature of an acceptor defect. Numerical simulations using the near-surface defects model show the signatures of interface recombination without the need for a reduced interface bandgap or Fermi-level pinning. These findings demonstrate that the VOC,in measurements alone can be inconclusive and might conceal the information on interface recombination pathways, establishing the need for complementary techniques like temperature dependent current–voltage measurements to identify the cause of interface recombination in the devices. [less ▲]

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See detailThe impact of Kelvin probe force microscopy operation modes and environment on grain boundary band bending in perovskite and Cu(In,Ga)Se2 solar cells
Martin Lanzoni, Evandro UL; Gallet, Thibaut UL; Spindler, Conrad UL et al

in Nano Energy (2021), 88

An in-depth understanding of the electronic properties of grain boundaries (GBs) in polycrystalline semiconductor absorbers is of high importance since their charge carrier recombination rates may be very ... [more ▼]

An in-depth understanding of the electronic properties of grain boundaries (GBs) in polycrystalline semiconductor absorbers is of high importance since their charge carrier recombination rates may be very high and hence limit the solar cell device performance. Kelvin Probe Force Microscopy (KPFM) is the method of choice to investigate GB band bending on the nanometer scale and thereby helps to develop passivation strategies. Here, it is shown that the workfunction, measured with amplitude modulation (AM)-KPFM, which is by far the most common KPFM measurement mode, is prone to exhibit measurement artifacts at grain boundaries on typical solar cell absorbers such as Cu(In,Ga)Se2 and CH3NH3PbI3. This is a direct consequence of a change in the cantilever–sample distance that varies on rough samples. Furthermore, we critically discuss the impact of different environments (air versus vacuum) and show that air exposure alters the GB and facet contrast, which leads to erroneous interpretations of the GB physics. Frequency modulation (FM)-KPFM measurements on non-air-exposed CIGSe and perovskite absorbers show that the amount of band bending measured at the GB is negligible and that the electronic landscape of the semiconductor surface is dominated by facet-related contrast due to the polycrystalline nature of the absorbers. [less ▲]

Detailed reference viewed: 166 (17 UL)