Formation of a Two-Phase Structure in CH 3 NH 3 PbI 3 Organometallic Perovskite

The effect of annealing of a CH3NH3PbI3 organometallic perovskite film on its electrical, photoelectrical, and optical properties is studied. It is shown that annealing at the temperature Ta > 140°C results in the formation of a two-phase structure consisting of perovskite and lead iodide, whose relative content depends on the conditions of annealing, specifically, on the annealing temperature. The formation of PbI2 in the perovskite structure yields a decrease in the conductivity and photoconductivity of the material. The studies suggest the possibility of the formation of planar structures composed of semiconductor materials with different band gaps, 1.6 eV (CH3NH3PbI3) and 2.4 eV (PbI2).