High performance CsPbBr3 epitaxial film photodetector with ultralow dark current and record detectivity

At present, spin coating is commonly used for perovskite film detectors, which has large photocurrent in the dark state due to the poor control on film growth and low crystal quality. In this Letter, pulsed laser deposition has been introduced to grow high quality CsPbBr3 epitaxial films, and the effect of substrate temperature on the film quality was studied during the epitaxial process. Planar metal–semiconductor–metal photoconductive detectors based on such epitaxial CsPbBr3 thin films with dark current as low as 11 pA at a bias voltage of 2 V was achieved. Under the illumination of a 450 nm laser with a power density of 0.65 μW cm−2, the responsivity, external quantum efficiency, and detectivity of the devices reach 12.796 AW−1, 2996%, and 3.38 × 1014 Jones, respectively. The maximum on/off ratio can be 2.38 × 105 under high-intensity 450 nm laser irradiation of 148 mW cm−2. In contrast, the spin-coated CsPbBr3 film-based detector with the same device configuration exhibit dark current that is two orders of magnitude higher and an on/off ratio of three orders of magnitude smaller than those of the epitaxial film devices. Therefore, due to their high-quality, thickness-control, and easy-integration, such epitaxial perovskite thin films can be used as a platform for the study of more functionalities of halide perovskite semiconductors and related devices.