Solution-Processed Transparent Sn4+-Doped CuI Hybrid Photodetectors with Enhanced Performances

Herein, Sn4+-doped copper (I) iodide (CuI) is prepared via a facile, cost-efficient solution process, and the properties of Sn4+-doped CuI, including morphology, crystalline phase, as well as optical and electrical properties, are investigated by varying the Sn4+ concentration. And by constructing transparent Sn4+-CuI/ZnO hybrid UV photodetectors, the potential of Sn4+-CuI as a p-type material for high-performance photodetection is investigated. It is found that Sn4+ doping has great effect on the morphology as the formation of Sn4+-CuI thin sheets is observed, and the resistivity of Sn4+-CuI could be tuned by controlling Sn4+ addition. The Sn4+-CuI/ZnO hybrid photodetectors exhibit obviously enhanced photodetecting performance outperforming ZnO film and CuI/ZnO photodetectors by the same preparation method, including significantly improved on/off ratio, spectral responsivity, and shortened responsive time. The enhanced performance of Sn4+-CuI/ZnO hybrid photodetectors mainly arises from the formation of type-II p-Sn4+-CuI/n-ZnO heterojunctions, and the better interface contact leads to higher carrier separation efficiency due to the existence of Sn4+-CuI thin sheets. And the improved performance is also related to the optimized resistivity of Sn4+-CuI. This study sheds light on the potential of doped CuI toward transparent, high-performance photodetectors in the future.