Photoresponse properties and energy gap of CsPbBr_3-CsPb_2Br_5 compound thin film prepared by one-step thermal evaporation method

摘要

We proposed the preparation of the compound thin film of CsPb_2Br_5 and CsPbBr_3 perovskites via thermal evaporation method with post-annealing. The optical absorption, energy gap, and photoresponse properties of the compound thin films were investigated. Over 90% transmittance in visible region of 550-700 nm was obtained, and the energy gap of thin film was found to be in the range of 2.28-2.35 eV. Using 405 nm laser, the compound thin film showed obvious response dependence on light power. Even if the large conductive channel of 1 mm × 100 μm was used, thin film possessed still good cycle characteristics, available responsivity, and a rapid response at applying 5 V.