Proceedings of Perovskite Thin Film Photovoltaics (ABXPV17)
Publication date: 18th December 2016
Organic-inorganic hybrid perovskite absorbers for solar cell applications attracted enormous attention of the scientific community during the last years. Nowadays, perovskite solar cells have reached efficiencies above 20% [1]. Still, to find fabrication processes applicable to upscaling from laboratory to commercial solar cell sizes remains a task to work on. The closed space sublimation (CSS) proved to be such an upscalable process for other thin film technologies like CdTe solar cells. In our lab we combine a conventional evaporation of PbCl2, PbI2 or SnI2 with the transformation of those base layers to CH3NH3PbI3 (MAPI) and CH3NH3SnI3 (MASI) perovskites via a CSS process. Both processes are carried out under ultra high vacuum (UHV) conditions. In addition, a XPS/UPS system is directly connected to our fabrication chambers, which allows in situ PES experiments on MAPI and MASI layers, without breaking the UHV conditions. We present the comparison between an open transformation process of lead salt layers to MAPI with a CSS process, that should allow shorter transformation times and higher substrate temperatures. In addition, the fabrication conditions required for the production of MAPI and MASI perovskite layers with the CSS process will be shown. The analysis of the layers is mainly done with XPS, XRD and SEM. Emphasis will be laid on the electronic and chemical surface properties of the CSS perovskites. Furthermore, the potential the CSS process offers for tuning the morphology of the MAPI and MASI layers will be discussed.
[1] NREL solar cell efficiency chart (http://www.nrel.gov/ncpv/)