Research On High Quality MAPbI₃ Nanowires With Ultra Long Carrier Lifetime And Photodetectors

Solution-processable single crystal perovskite films are superior to their polycrystalline counterparts in terms of carrier lifetime,because fewer grain boundaries result in reduced carrier recombination losses.Single crystalline perovskite nanowires are ideal candidates for photodetection and other optoelectronic applications due to their unique advantage of allowing the manipulation of light and carriers in nanoscale via the naturally formed boundaries.Although researchers have made great efforts to grow high-quality single crystal perovskite nanowires for photoelectric detection,their sides are rough,accompanied by a certain number of defects,which worsens the dark current,so limits the ability to detect low light.And single crystal perovskite nanowires have a much shorter carrier lifetime than bulk perovskite single crystals.This work has based on the surface initiated solution growth method with fine kinetic control to fabricate high quality single crystalline MAPbI₃nanowires with atomically smooth sides and a carrier life time as long as 81ns.The as-prepared metal-semiconductor-metal photodetector has an extremely low dark current of 180 f A under 1 V bias,and a current of 340 p A under illumination of 10.2 m W/cm²,corresponding to an on-off current ratio of1880,which is the largest on-off ratio in photodetectors based on MAPbI₃nanowires without any passivation treatment.We have also manufactured high performance metal-semiconductor-metal photodetector based on multiple MAPbI₃ nanowires through dry contact transfer technology.The demonstrated photodetector has a record large linear dynamic range of 157 d B,which can detect the illumination with a power density as low as 5.5 n W/cm²,leading to a record high detectivity of 2.4×10¹⁴Jones,compared with all previous reports of MAPbI₃ nanowire photodetectors.Such superior photodetector performance is attributed to two aspects.First,the as-grown MAPbI₃ nanowires exhibit atomically smooth side surfaces,which brings forward reduced amount of defects and thereby a quite low noise current.Second,the long carrier life time of the prepared MAPbI₃ nanowires gives rise to an improved responsivity under light illumination.We also characterized the performance of the device at low temperatures.As the temperature decreases,the light to dark current ratio of the device is greatly improved,reaching a value as high as 3.95×10⁷ at 85 K.The response of the device is more rapid,and the detection rate is also enhanced.Therefore,the device has better photoelectric detection performance at low temperature than normal temperature.The realized high-performance MAPbI₃ nanowire photodetector will promote the development of low-cost photodetectors and find potential applications in weak-signal photoelectric detection and low-temperature detection.