Crystallization reaction from intermediate phase with [0 0 2] preferential crystalline orientation to MAPbI3 and its influence on the performance of perovskite solar cells

Intermediate phase film (MAI-PbI2-DMSO) with [0 0 2] preferential crystalline orientation was prepared, which was not stable at room temperature. Many pinholes form by directly heating it at 100 °C. Smooth and homogeneous MAPbI3 films can be obtained by adding a stage of low temperature preheating process to restrain the rapid effusion of DMSO molecules. A high PCE of 15.43% was achieved for NiOx-based inverted planar perovskite solar cells.