Photomodulated Hysteresis Behaviors in Perovskite Phototransistors with Ultra-Low Operating Voltage

Hysteresis behaviors in the current curves of perovskite-based devices have been widely observed and directly affect the device performances. Phototransistors with a channel material of CH₃NH₃PbI₃ were fabricated, and they showed ambipolar transport characteristics with anticlockwise hysteresis hoops. Electric field and monochromatic light can narrow the wide hysteresis window from 2.1 V in the dark to only 0.5 V under the illumination. A photoexcited high-field-effect carrier mobility of 1.05 cm² V^-1 s^-1 was achieved at a low-operating voltage. The responsivity and photosensitivity of the phototransistor were calculated to be 1 AW^-1 and 18 000%, respectively. The modulation effect of voltage bias and monochromatic lights on such hysteresis behaviors has been demonstrated. By investigating the photo-sensitive carrier-transport characteristics in perovskite channel, the origin of hysteresis can be attributed to the charge-trapping process. This work also provides an effective approach to achieve a photocontrolled temporary erasing process as a data protection mechanism in future photomemory devices.