A controllable fabrication of grain boundary PbI2 nanoplates passivated lead halide perovskites for high performance solar cells

We demonstrate a controllable formation of grain boundary Pbl(2)nanoplates passivated CH3NH3PbI3 and CH3NH3PbI2Br perovskites for high performance solar cells with up to 17.8% and 14.4% efficiencies, which are higher than the corresponding phase pure perovskite solar cells. The Pbl(2) passivated planar perovskite films were facilely prepared via direct gas/solid reaction of hydrohalide deficient Pbl(2)center dot xHI/Br precursor with CH3NH2 gas. The amount of Pbl(2) impurities can be controlled by adjusting the hydro halide deficiency in the precursors. The crystal growth investigation suggested that the Pbl(2) is highly like to form during the annealing crystallization process instead of existing in either the Pbl(2)center dot xHI/Br precursor films or as grown perovskite films. The Pbl(2) with controllable amount locating at grain boundary could effectively passivate the perovskites with a longer PL lifetime and enhanced V-oc. (C) 2016 Elsevier Ltd. All rights reserved.