Temperature-Dependent Electric Field-Induced Optical Transitions of 2D Molybdenum Disulfide (MoS₂) Thin Films: Temperature-Dependent Electroabsorption and Absorption

Abstract

Two-dimensional (2D) layered MoS2 nanosheets (NSs) possess many unique properties and hold great potential for various applications. Herein, MoS2 NSs were synthesized by a hydrothermal method. The as-synthesized MoS2 NSs are crystalline and layered. Absorption and electroabsorption (E-A) spectra of MoS2 doped in a poly­(methyl methacrylate) (PMMA) thin film were measured at different temperatures (290–40 K). The E-A spectra detected at the second harmonic of the modulation frequency of the applied electric field were analyzed using an integral method by considering the Stark effect as a dominant feature. The absorption spectra consist of seven transitions, among which five transitions are contributed to the E-A spectra. It is found that the changes in the electric dipole moment and polarizability of each transition determined at different temperatures increase substantially with decreasing temperature. Electronic resonance states identified for low-energy excitonic bands of MoS2 NSs showed prominence E-A signals. The study is essential to understand the electronic structure in the photoexcited state, which is important for applications of MoS2 NSs to optoelectronic devices