PbI 2 platelets for inverted planar organolead Halide Perovskite solar cells via ultrasonic spray deposition

Morphology control of organometal halide perovskite thin films is of importance in order to develop highly efficient perovskite solar cells. Here, a seeded growth method is introduced for the first time to deposit lead iodide (PbI 2 ) with platelet structures on an organic hole transporting layer PEDOT:PSS. The PbI 2 platelets are effectively converted into perovskite thin film when subject to sprayed droplets of methylammonium in isopropyl alcohol. Compared with evaporated compact PbI 2 layers, the PbI 2 platelet enables a thicker perovskite thin film to be formed with less unreacted PbI 2 . Using this technique, we have achieved pinhole-free and uniform perovskite thin film with root-mean-square roughness of 12.81 nm, and an average solar cell efficiency higher than those fabricated from compact PbI 2 thin film.