Long-term instability of organo-metal halide (OMH) perovskite materials is a critical issue that affects their applications including photovoltaics. The instability is at least in part determined by surface properties of the materials. Herein, we have used oleic acid (OA) as a hydrophobic encapsulant to improve the stability of methylammonium lead iodide (CH3NH3PbI3) perovskite films as well as solar cells against humidity through surface passivation. The stability was tested in a course of four weeks in air at humidity levels of ≥ 76%. The OA-treated films have only experienced a degradation of ~ 5% after 4 weeks, while non-treated films fully degraded within the first week. Solar cells based on the methylammonium lead iodide films with OA for passivation have showed slightly higher values of open circuit voltage, fill factor, and overall photocurrent conversion efficiency, which are attributed to the ability of OA to reduce charge carrier recombination at the device interfaces. Moreover, unlike the control device, OA has stabilized the performance of solar cell stored in highly humid conditions.

Enhancing stability of organolead iodide perovskite films and solar cells with surface chemistry approach

254th National Meeting (2017)

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