TiO₂ Nanorod/CH₃NH₃PbCl₃ Perovskite Core-shell Hybrid Structure Arrays For Sensitive UV Photodetector And Image Sensor Applications

High-performance photodetectors operating in the visible-blind ultraviolet?UV?spectrum region are highly required for their essential civilian and military applications including environment monitoring,chemical and biological analysis,flame detection,remote control and secure space-to-space communication.Titanium dioxide?TiO₂?,especially in its one-dimensional configurations?e.g.,nanowires,nanorods?NRs?,nanotubes?NTs??is highly suitable for sensitive UV photodetection due to its excellent physical,chemical and optical characteristics.By virtue of the pronounced light trapping effect of the vertical nanostructures array,the vertical nanostructures array are favorable for optoelectronic applications.However,UV photodetectors based on TiO₂nanostructures can affect the separation and suppression of photogenerated carriers due to surface self-composite and defect states.In order to solve the above problems,we have developed TiO₂NRs array/CH₃NH₃Pb Cl₃heterojunction UV photodetectors to investigate the photoelectric properties of this detector and analyze its potential applications in future UV optoelectronic systems.The specific tasks are as follows:In this dissertation,we developed a sensitive visible-blind UV photodetector by directly coating the CH₃NH₃Pb Cl₃perovskite film onto vertical TiO₂nanorods?TiO₂NRs?array.Photoresponse analysis reveals that the as-constructed TiO₂NRs/perovskite core-shell heterojunction was very sensitive to light irradiation in the UV regime with peak sensitivity at around 365 nm,but virtually blind to light illumination with wavelength longer than 400 nm.Under 365 nm illumination,the responsivity and specific detectivity were calculated to be?50 m A/W and?5.39×10¹⁰Jones,respectively,at a bias of 2 V.In addition,the device exhibited excellent ambient stability.The relatively good device performance is related to the pronounced light confinement effect of the unique geometry of the core-shell heterojunction array,according to our theoretical simulation.Moreover,the present device can also record the“LASDOP”image produced by the UV illumination with reasonable resolution.It was observed that the heterojunction displayed high sensitivity to the UV illumination.Further optoelectronic analysis found that the detector achieved high responsivity and high specific detectivity,along with a good stability in ambient conditions.According to a numerical simulation based on the finite-difference time-domain?FDTD?method,such a decent device performance can be related to the strong light confinement effect of the core-shell heterojunction array.Finally,the present device can also function as an image sensor to record a“LASDOP”image produced by the 365 nm illumination.It is believed that the UV photodetector based on the TiO₂NRs array/CH₃NH₃Pb Cl₃core-shell heterojunction can find potential application in future UV optoelectronic systems.