Preparation of CH₃NH₃PbI₃ thin films with tens of micrometer scale at high temperature

The fabrication of high-quality organic-inorganic hybrid halide perovskite layers is the key prerequisite for the realization of high efficient photon energy harvest and electric energy conversion in their related solar cells. In this article, we report a novel fabrication technique of CH₃NH₃PbI₃ layers based on high temperature chemical vapor reaction. CH₃NH₃PbI₃ layers have been prepared by the reaction of PbI₂ films which were deposited by pulsed laser deposition, with CH₃NH₃I vapor at various temperatures from 160 °C to 210 °C. X-ray diffraction patterns confirm the formation of pure phase, and photoluminescence spectra show the strong peak at around 760 nm. Scanning electron microscopy images confirm the significantly increased average grain size from nearly 1 μm at low reaction temperature of 160 °C to more than 10 μm at high reaction temperature of 200 °C. The solar cells were fabricated, and short-circuit current density of 15.75 mA/cm², open-circuit voltage of 0.49 V and fill factor of 71.66% have been obtained.