Self-Powered Flexible Ultraviolet Photodetectors Based on CuI/a-ZTO Heterojunction Processed at Room Temperature

Fortraditional wide-bandgap semiconductor materials, a high-temperatureprocess is unavoidable for improving crystallization quality, so thesubstrate of the device is greatly limited. In this work, zinc-tinoxide (a-ZTO) amorphous oxide processed by the pulsed laser depositionmethod was utilized as the n-type layer, which exhibits considerableelectron mobility and optical transparency, and can be deposited atroom temperature. At the same time, by combining p-type CuI grownby the thermal evaporation method, a vertically structured ultravioletphotodetector based on CuI/ZTO heterojunction was obtained. The detectordemonstrates self-powered properties, with an on-off ratioexceeding 10(4), and rapid response with a rise time of 2.36ms and a fall time of 1.49 ms. Also, the photodetector shows long-termstability with 92% retention after 5000 s cyclic lighting and maintainsreproducible response in frequency dependence measurement. Furthermore,the flexible photodetector on poly(ethylene terephthalate) (PET) substrateswas constructed, exhibiting fast response and durability in the bendingstate. This is the first time that the heterostructure based on CuIhas been applied in the flexible photodetector. The excellent resultsindicate that the combination of amorphous oxide and CuI has the potentialfor ultraviolet photodetectors, and will broaden the application rangeof high-performance flexible/transparent optoelectronic devices inthe future.