Excitonic Effects in the Linear and Nonlinear Optical Response of Rhenium Disulfide Regulated by Re Vacancy

Abstract

AbstractRhenium disulfide (ReS2) with low structural symmetry and highly spontaneous, exhibits some unique optical and electrical anisotropy properties for developing optoelectronic devices. This work studies the hydrothermal synthesis and the excitonic effects in the linear and nonlinear optical properties of 1T′ phase ReS2. The growth is controlled by adjusting experimental conditions, and its growth mechanism is revealed. The varying degrees of Re vacancy are characterized. They cause the growth direction of ReS2 nanosheets from lateral to agglomeration and the stacks into self‐assembly micro‐nanospheres. The density functional theory explains the electronic and bonding properties of Re vacancy, where the existent defects reduce the band gap and change the states density. Re vacancy increases the conductivity and results in the metallization of ReS2. The photoluminescence intensity of defect emission peak is negatively correlated with the defect level for the enriching vacancies. However, compared with intrinsic peak, it will increase monotonically with the number of bound excitons in defects. Furthermore, the nonlinear absorption properties are obtained by picosecond Z‐scan technique. By adjusting temperature, different degrees of saturation absorption and reverse saturation absorption characteristics appear due to the vacancy effect. The synthesized ReS2 has broad application in photodetectors and optical devices with optical amplitude limiting.