Defect recombination suppression and carrier extraction improvement for efficient CsPbBr 3 /SnO 2 heterojunction photodetectors.

Perovskite materials with excellent optical and electronic properties have huge potential in the research field of photodetectors. Constructing heterojunctions and promoting carrier transportation are significant for the development of perovskite-based optoelectronics devices with high performances. Herein, we demonstrated a CsPbBr ₃ /SnO ₂ heterojunction photodetector and improved the device performances through post-annealing treatment of SnO ₂ film. The results indicated that the electrical properties of SnO ₂ films will make an important impact on carrier extraction, especially for type-II heterojunction. As the electrons transfer layer in CsPbBr ₃ /SnO ₂ type-II heterojunction, defects related to oxygen vacancy should be the key factor to affect carrier concentration, induce carriers' limitation and recombination rate. Under proper annealing temperature for SnO ₂ layer, the recombination rate can decrease to 1.37 × 10 ²¹ cm ³ s and the spectral responsivity will be highly increased. This work can enhance the understanding on the photoresponse of perovskite photodetectors, and will be helpful for the further optimization and design of optoelectronic devices based on the perovskite heterojunction.
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