Lead-free perovskite/ZnO heterostructure for flexible visible-blind ultraviolet photodetection

With the increasing demand for wearable, portable, and implantable optoelectronic devices, flexible photodetectors have become the hotspots of scientific pursuit. In this work, a flexible heterostructure photodetector was fabricated through a combination of perovskite CsCu2I3 nanorods and ZnO quantum dots by a facile solution method. The heterostructure combines the good bending resistance, low dark current, and excellent photoelectric conversion efficiency of CsCu2I3 nanorods with the high electron mobility of ZnO quantum dots; CsCu2I3 NRs act as the light compensating material and hole collector, while ZnO serves as an electron transport channel. This combination results in stronger UV absorption and reduced influence of visible light, achieving ultraviolet-to-visible rejection ratios of as high as 8 × 102. The photodetector exhibits superior performance in the visible-blind ultraviolet region, boasting an on–off ratio of 102, a tenfold increase compared to single-component CsCu2I3 NR photodetectors. Its responsivity and specific detectivity, at 1.62 A/W and 4.13 × 1011 Jones, respectively, outperform the single-component CsCu2I3 NRs by 40 and 23 times and surpass the single-component ZnO photodetectors by 102 times. The response time is about 50% shorter than that of the single-component CsCu2I3 and ZnO photodetectors. This photodetector also shows excellent flexibility and environmental and mechanical stability after a series of sharp bends. The results indicate that the CsCu2I3/ZnO heterostructure provides a promising alternative for high-performance flexible UV optoelectronics.