Low defects, large area and high stability of all-inorganic lead halide perovskite CsPbBr thin films with micron-grains heat-spraying process for self-driven photodetector.

All-inorganic lead halide perovskite CsPbBr has important applications in photoelectronic devices such as photodetectors, LEDs and photovoltaic devices. However, preparing high-quality CsPbBr thin films has proven to be challenging. In this study, we prepared all-inorganic lead halide perovskite CsPbBr thin films with micron-grains (MG-CsPbBr-TF) a heat-spraying process (HSP) using a CsPbBr-saturated solution (CsPbBr-SS), and the films exhibited large area, low defects and high stability. The grain size of MG-CsPbBr-TF was about 1-5 microns. The micron-sized grains in MG-CsPbBr-TF enabled the absorption cutoff edge to be extended from 537 to 545 nm. In addition, the presence of fewer boundaries in MG-CsPbBr-TF reduced the defects in MG-CsPbBr-TF (the blue shift of luminescence). The response wavelengths of a low-cost and self-driven (zero-biased) photodetector based on MG-CsPbBr-TF were from 330 to 600 nm. CsPbBr thin films having a large area (10 cm × 10 cm) and micron-sized grains were also prepared by HSP and exhibited excellent stability (1944 h) in air ( = 298 K, 40% humidity). To the best of our knowledge, this is the first study of high-quality CsPbBr thin films prepared by HSP. The results are of great interest for both fundamental research and practical applications of CsPbBr in photodetectors, LEDs and photovoltaic devices.