References of "Siebentritt, Susanne 50003089"
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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 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 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 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 ▲]

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See detailHow photoluminescence can predict the efficiency of solar cells
Siebentritt, Susanne UL; Weiss, Thomas UL; Sood, Mohit UL et al

in JPhys Materials (2021)

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See detailThe effect of KF post-deposition treatments on the optoelectronic properties of Cu(In,Ga)Se2 single crystals
Ramirez Sanchez, Omar UL; Bertrand, Maud; Debot, Alice UL et al

in Solar RRL (2021)

The power conversion efficiency boost of Cu(In,Ga)Se2 in the past years has been possible due to the incorporation of heavy alkali atoms. Their addition through post-deposition treatments results in an ... [more ▼]

The power conversion efficiency boost of Cu(In,Ga)Se2 in the past years has been possible due to the incorporation of heavy alkali atoms. Their addition through post-deposition treatments results in an improvement of the open-circuit voltage, which origin has been associated with grain boundaries. The present work discusses the effect of potassium fluoride post-deposition treatments on the optoelectronic properties of a series of sodium-free Cu(In,Ga)Se2 single crystals with varying Cu and Ga content. Results suggest that improvement of the quasi-Fermi level splitting can be achieved despite the absence of grain boundaries, being greater in low-gallium Cu-poor absorbers. Secondary ion mass spectrometry reveals the presence of potassium inside the bulk of the films, suggesting that transport of potassium can occur through grain interiors. In addition, a type inversion from n to p in KF-treated low-gallium Cu(In,Ga)Se2 is observed, which along a carrier lifetime study demonstrates that potassium can act as a dopant. The fact that potassium by its own can alter the optoelectronic properties of Cu(In,Ga)Se2 single crystals demonstrates that the effect of post-deposition treatments goes beyond grain boundary passivation. [less ▲]

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See detailHow band tail recombination influences the open-circuit voltage of solar cells.
Wolter, Max UL; Carron, Romain; Avancini, Enrico et al

in Progress in Photovoltaics (2021)

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See detailAbsorber composition: A critical parameter for the effectiveness of heat treatments in chalcopyrite solar cells
Sood, Mohit UL; Elanzeery, Hossam UL; Adeleye, Damilola UL et al

in Progress in Photovoltaics (2020)

Post-device heat treatment (HT) in chalcopyrite [Cu(In,Ga)(S,Se)2] solar cells is known to improve the performance of the devices. However, this HT is only beneficial for devices made with absorbers grown ... [more ▼]

Post-device heat treatment (HT) in chalcopyrite [Cu(In,Ga)(S,Se)2] solar cells is known to improve the performance of the devices. However, this HT is only beneficial for devices made with absorbers grown under Cu-poor conditions but not under Cu excess.. We present a systematic study to understand the effects of HT on CuInSe2 and CuInS2 solar cells. The study is performed for CuInSe2 solar cells grown under Cu-rich and Cu-poor chemical potential prepared with both CdS and Zn(O,S) buffer layers. In addition, we also study Cu-rich CuInS2 solar cells prepared with the suitable Zn(O,S) buffer layer. For Cu-poor selenide device low-temperature HT leads to passivation of bulk, whereas in Cu-rich devices no such passivation was observed. The Cu-rich devices are hampered by a large shunt. The HT decreases shunt resistance in Cu-rich selenides, whereas it increases shunt resistance in Cu-rich sulfides.. The origin of these changes in device performance was investigated with capacitance-voltage measurement which shows the considerable decrease in carrier concentration with HT in Cu-poor CuInSe2, and temperature dependent current-voltage measurements show the presence of barrier for minority carriers. Together with numerical simulations, these findings support a highly-doped interfacial p+ layer device model in Cu-rich selenide absorbers and explain the discrepancy between Cu-poor and Curich device performance. Our findings provide insights into how the same treatment can have a completely different effect on the device depending on the composition of the absorber. [less ▲]

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See detailPassivation of the CuInSe2 surface via cadmium pre-electrolyte treatment
Kameni Boumenou, Christian UL; Babbe, Finn; Elizabeth, Amala et al

in Physical Review Materials (2020)

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See detailPhonon coupling and shallow defects in CuInS2
Lomuscio, Alberto UL; Sood, Mohit UL; Melchiorre, Michele UL et al

in Physical Review. B (2020), 101(8), 085119-

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See detailOxidation as Key Mechanism for Efficient Interface Passivation in Cu(In,Ga)Se2 Thin-Film Solar Cells
Werner, Florian UL; Veith-Wolf, Boris; Spindler, Conrad UL et al

in Physical Review Applied (2020)

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See detailOn the chemistry of grain boundaries in CuInS2 film
Schwarz, Torsten; Lomuscio, Alberto UL; Siebentritt, Susanne UL et al

in Nano Energy (2020), 76

Detailed reference viewed: 143 (2 UL)