Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 64: Poster: Photovoltaics and Optics
HL 64.27: Poster
Wednesday, March 22, 2017, 15:00–19:00, P1C
Co-evaporated CZTSe solar cells: influence of Cu deposition rate during precursor processing on the growth and device performance — Lwitiko Mwakyusa1,4, •Markus Neuwirth1, Max Reimer1, Simon Woska1, Willi Kogler2, Thomas Schnabel2, Erik Ahlswede2, Bryce Richards3,4, Heinz Kalt1, and Michael Hetterich1,3 — 1Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), 70565 Stuttgart, Germany — 3Light Technology Institute, KIT, 76131 Karlsruhe, Germany — 4Institute of Microstructure Technology, KIT, 76344 Karlsruhe, Germany
The performance of Cu2ZnSnSe4 (CZTSe) thin film solar cells is still limited by a high open-circuit voltage deficit and low fill factor. To boost device performance it is crucial to improve grain size and quality, control the formation of defects and inhibit the formation of secondary phases. It is often assumed that a Cu–Se eutectic liquid-phase is beneficial for the growth of a high-quality CZTSe absorber layer. However, too much Cu may provoke the formation of Cu2-xSe which can act as a shunt path in the solar cell thus deteriorating overall device performance. In this contribution we investigate solar cells with CZTSe absorbers fabricated using low-temperature co-evaporation and following high-temperature annealing in a Se atmosphere. The Cu concentration in the absorber is varied by changing the Cu deposition rate during precursor deposition. The finished devices are compared with respect to their performance in order to optimize growth conditions.