Dresden 2017 – wissenschaftliches Programm
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.