High-responsivity two-dimensional p-PbI2/n-WS2 vertical heterostructure photodetectors enhanced by photogating effect

Two-dimensional (2D) vertical p-n heterostructure photodetectors are significant building blocks in nanoscale integrated opto-electronics. However, the unsatisfactory photosensing performance combined with a complicated fabrication process still remains a challenge. In this work, the fabrication of high-performance vertical photodetectors based on vapor-grown p-PbI2/n-WS2 heterostructures has been reported, where WS2 serves as the photogate to modulate the channel current. Due to the photogating effect in heterostructures, the recombination of photoexcited electron-hole pairs is effectively suppressed, leading to high photoresponsivity up to 5.57 x 10(2) AW(-1), which represents the highest value among any other reported vapor-grown vertical p-n heterostructures. Moreover, the photoresponsivity is highly tunable through the gate voltage bias, and it can be further improved to 7.1 x 10(4) A W-1 by applying a negative gate voltage bias of -60 V. The excellent photosensing properties of the PbI2/WS2 heterostructures combined with the facile synthesis method reveal the promising potential in developing high-performance 2D opto-electronic devices.