| Autor: |
Kogler, Willi, Schnabel, Thomas, Ahlswede, Erik, Taskesen, Teoman, Gütay, Levent, Hauschild, Dirk, Weinhardt, Lothar, Heske, Clemens, Seeger, Jasmin, Hetterich, Michael, Powalla, Michael |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 4/30/2020, Vol. 127 Issue 16, p1-9, 9p, 2 Charts, 5 Graphs |
| Abstrakt: |
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, the external quantum efficiency (EQE) of the Zn(O,S)-buffered devices increases in the short- and long-wavelength regions of the spectrum. However, the average EQE ranges below that of the CdS reference, and the devices show a low open-circuit voltage (VOC). By adding a very thin CdS layer (5 nm) between the absorber and the Zn(O,S) buffer, the VOC loss is completely avoided. Using thicker intermediate CdS layers result in a further device improvement, with VOC values above those of the CdS reference. X-ray photoelectron spectroscopy (XPS) measurements suggest that the thin CdS layer prevents damage to the absorber surface during the sputter deposition of the Zn(O,S) buffer. With the hybrid buffer configuration, a record VOC deficit, i.e., a minimum difference between bandgap energy Eg (divided by the elementary charge q) and VOC (Eg/q – VOC) of 519 mV could be obtained, i.e., the lowest value reported for kesterite solar cells to date. Thus, the hybrid buffer configuration is a promising approach to overcome one of the main bottlenecks of kesterite-based solar cells, while simultaneously also reducing the amount of cadmium needed in the device. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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