Chemical vapor deposition growth of phase-selective inorganic lead halide perovskite films for sensitive photodetectors

Inorganic lead halide perovskites are attractive optoelectronic materials owing to their relative stability compared to organic cation alternatives. The chemical vapor deposition (CVD) method offers potential for high quality perovskite film growth. The deposition temperature is a critical parameter determining the film quality owing to the melting difference between the precursors. Here, perovskite films were deposited by the CVD method at various temperatures between 500-800 ℃. The perovskite phase converts from CsPb₂Br₅ to CsPbBr₃ gradually as the deposition temperature is increased. The grain size of the perovskite films also increases with temperature. The phase transition mechanism was clarified. The photoexcited state dynamics were investigated by spatially and temporally resolved fluorescence measurements. The perovskite film deposited under 750 ℃ condition is of the CsPbBr₃ phase, showing low trap-state density and large crystalline grain size. A photodetector based on perovskite films shows high photocurrent and an on/off ratio of ~2.5×10⁴.