Highly reproducible perovskite solar cells via controlling the morphologies of the perovskite thin films by the solution-processed two-step method

Organic-inorganic halide perovskites are one of the most attractive materials for the next generation solar cells. The PCE has rapidly increased to more than 22% using different configurations and techniques and further developments are predicted. However, perovskite solar cells suffer from fabrication reproducibility mainly due to difficulty in controlling the morphology of the perovskite films themselves. In this paper we present a low temperature solution-processed two-step deposition method to fabricate CH3NH3PbI3 perovskites. This method offers a simple route with great potential in fabricating reproducible perovskite solar cells. In the present work, we demonstrate that the morphology of the perovskite thin films is highly determined by the concentration of Methylammonium iodide (MAI) as well as the reaction time between MAI and PbI2. High-performance solar cells have been reproducibly achieved with a highest PCE of 15.01% for PCBM-based planar heterojunction solar cells.