Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 8: Photovoltaics

HL 8.3: Vortrag

Montag, 20. März 2017, 10:00–10:15, POT 251

Investigation of the Loss Mechanisms in CuInS₂/ZnO Nanocrystal Solar Cells — •Dorothea Scheunemann, Sebastian Wilken, Holger Borchert, and Jürgen Parisi — University of Oldenburg, Department of Physics, Energy and Semiconductor Research Laboratory, 26111 Oldenburg

Heterojunction solar cells based on colloidal nanocrystals have shown remarkable improvements in performance in the last decade. This progress was accompanied by a deeper understanding of the underlying physical processes in nanocrystal solids and devices. However, the vast majority of these studies is focused on two materials, PbS and PbSe. In contrast, there is still a lack of such detailed knowledge in case of other materials, as for example copper-based compounds, which show lower power conversion efficiencies when incorporated into solar cells. Here, we present a detailed study on the photocurrent loss mechanisms in nanocrystalline CuInS₂/ZnO heterojunction solar cells by combining steady-state characterization methods with transient photocurrent and photovoltage measurements. We demonstrate the presence of two different loss mechanisms: An extraction barrier at the CuInS₂/ZnO interface, which can be reduced upon illumination with UV light, as well as significant trap-assisted recombination in the CuInS₂ layer. The presented results confirm the potential of heterojunctions made from CuInS₂ and ZnO nanocrystals in solution producible solar cells, but also clearly highlight the importance of a substantial reduction of sub-band gap states to improve the performance.