Quantum efficiency gain in perovskite detectors

Metal halide perovskite semiconductors are emerging low-cost materials for photovoltaics, light emitting devices and detectors. Because of the inclusion of high atomic numbered elements, perovskites are promising candidates for high efficiency X-ray sensing. In this talk, I will discuss the properties of perovskite semiconductors for X-ray and visible photon sensing. Firstly, we report a long carrier diffusion length in 2D perovskite single crystals, assisted by the shallow trap and de-trapping process. Next, we show that such a long diffusion length ensures a full charge collection after charge ionization, which is beneficial for detectors for X-ray and visible photons. In addition, we have found the shallow trap also extend the carrier transport lifetime that facilitate a charge multiplication in the detector driven under high voltages. Such a process introduces a photo conductivity gain, leading to an unusually high X-ray and visible photon sensing efficiency. A high gain can be also achieved by building a hetero-structured device. Interfacing perovskites with a high mobility channel, such as graphene or n-type GaN can also multiplicate the photo-generated carriers. With a hetero-structured device, we show a high X-ray sensitivity over 10⁸ µCGy^-1cm^-2.