The effect of UVO treatment on TiO2-MAPbI3 heterostructure photodetector prepared in air atmosphere

TiO2-MAPbI3 heterostructure photodetectors were prepared in air atmosphere. The interface between electron transport layer and perovskite layer plays an important role in the performance of heterostructure photodetector. Here, ultraviolet ozone (UVO) treatment was used to improve the surface state of TiO2 film and the interfacial carrier transport performance of perovskite heterostructure photodetector. UVO treatment made TiO2 layer obtain the more oxygen vacancies and excess electrons, which were conducive to the electrical conductivity of electron transport layer. And MAPbI3 film deposited on UVO-treated TiO2 layer showed better uniformity and enhanced light absorption intensity due to the improved wettability of UVO-treated TiO2 film. Further research on photoelectric performance indicated that the increased light current and decreased dark current could be obtained for perovskite photodetector based on UVO-treated TiO2. In addition, the best exposure time was found to be 40 min. Compared with untreated sample, the detectivity of UVO-treated TiO2-MAPbI3 heterostructure photodetector increased by 80 %. Under 500 nm illumination with a light intensity of 1.6 mW cm-2 at-0.8 V bias, the responsivity, detectivity and external quantum efficiency of UVO-treated TiO2-MAPbI3 heterostructure photodetector reached 0.405 A W-1, 2.07 x 1011 Jones and 100.5 %, respectively.