All‐Inorganic Perovskite Quantum Dot‐Monolayer MoS₂ Mixed‐Dimensional van der Waals Heterostructure for Ultrasensitive Photodetector

Abstract

Abstract2D 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 CsPbI3− xBrx quantum dots are integrated with monolayer MoS2 for high‐performance and low‐cost photodetectors. A favorable energy band alignment facilitating interfacial photocarrier separation and efficient carrier injection into the MoS2 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 × 104 A W−1, a specific detectivity of ≈5.6 × 1011 Jones, and an external quantum efficiency exceeding 107%. 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.

Perovskite‐Based Phototransistors and Hybrid Photodetectors

“…They are a family of semiconducting layered materials with thickness‐dependent moderate bandgaps and reasonable charge carrier mobility . Some works have been conducted to adopt TMDs to replace graphene as transporting channel in perovskite/2D material hybrid phototransistors …”

Emerging Conductive Atomic Force Microscopy for Metal Halide Perovskite Materials and Solar Cells

“…Perovskite solar cells (PSCs) is an emerging thin film photovoltaic (PV) device with excellent power conversion efficiency (PCE), which have taken the PV research field by storm and attracted more and more intensive attention . Metal halide perovskites exhibit desirable optical–electrical properties for PV devices, such as high carrier mobility, long carrier diffusion lengths, wide and strong optical absorption, all of which enable the impressive PCE. Despite the significant progress in perovskite materials and PV devices, an in‐depth understanding of the fundamental photoelectric properties and the unusual phenomenon in operation is still lacking, which severely restricts the further development in practice .…”

Ligand Engineering for Improved All‐Inorganic Perovskite Quantum Dot‐MoS2 Monolayer Mixed Dimensional van der Waals Phototransistor

“…Such MvdWH‐based devices have been demonstrated to be promising for ultrasensitive and broadband detection with high responsivity and photogain, because of outstanding intrinsic characteristics of perovskite QDs and 2D layered materials, respectively. Even though the interfacial electronic structure has been sufficiently engineered to manipulate the charge carrier behavior, the residue ligands introduced by the QDs and remained at the interface are still believed to be the dominated factor for possibility of further improvement . Consequently, the inevitable influence originated from the ligand is expected to be effectively mitigated for desired device performance.…”

“…To further demonstrate the significant influence of ligand engineering on the interfacial charge carrier behavior as well as related mixed dimensional van der Waals device performance, we take a phototransistor as a model device. Considering our previous works on the energy band engineering of mixed dimensional van der Waals heterostructures, we adopted monolayer MoS 2 (Figures S1 and S2, Supporting Information) with direct bandgap and high mobility to function as channel material. After subsequent modification of perovskite QD with or without ligand treatment, we realized the 0D–2D mixed dimensional van der Waals phototransistor as schematically illustrated in Figure a.…”