All‐Inorganic Perovskite Quantum Dot‐Monolayer MoS 2 Mixed‐Dimensional van der Waals Heterostructure for Ultrasensitive Photodetector

Abstract 2D transition metal dichalcogenide (2D‐TMD) materials and their van der Waals heterostructures (vdWHs) have inspired worldwide efforts in the fields of electronics and optoelectronics. However, photodetectors based on 2D/2D vdWHs suffer from performance limitations due to the weak optical absorption of their atomically thin nature. In this work, taking advantage of an excellent light absorption coefficient, low‐temperature solution‐processability, and long charge carrier diffusion length, all‐inorganic halides perovskite CsPbI 3− x Br x quantum dots are integrated with monolayer MoS 2 for high‐performance and low‐cost photodetectors. A favorable energy band alignment facilitating interfacial photocarrier separation and efficient carrier injection into the MoS 2 layer inside the 0D–2D mixed‐dimensional vdWHs are confirmed by a series of optical characterizations. Owing to the synergistic effect of the photogating mechanism and the modulation of Schottky barriers, the corresponding phototransistor exhibits a high photoresponsivity of 7.7 × 10 4 A W −1 , a specific detectivity of ≈5.6 × 10 11 Jones, and an external quantum efficiency exceeding 10 7 %. The demonstration of such 0D–2D mixed‐dimensional heterostructures proposed here would open up a wide realm of opportunities for designing low‐cost, flexible transparent, and high‐performance optoelectronics.