Modulation On Optical And Electronic Properties Of Thin ReSe₂ Via Strain Engineering

In recent years,two-dimensional materials have broad application prospects in the fields of optoelectronic devices,flexible wearables,sensing,and energy storage due to their atomic layer thickness,large specific surface area,and excellent flexibility.Strain engineering can control the electronic structure of two-dimensional materials by affecting the lattice parameters of materials,which is one of the effective methods to control the physical properties of materials.Unlike two-dimensional materials with high lattice symmetry,such as graphene and molybdenum sulfide,rhenium diselenide?ReSe₂?with 1T phase exhibits anisotropy in the plane.The regulation provides a new degree of freedom,so that it reflects the electrical and optical characteristics of the in-plane anisotropy.This paper mainly takes ReSe₂ with low lattice symmetry as the research object,and carries out the following two parts in terms of strain regulation and its physical properties:?1?Study on the regulation of strain on the optical and electrical properties of ReSe₂.The dynamic adjustment of the electrical and optical properties of the material by changing the lattice structure is of great significance for the application of two-dimensional materials in flexible nanodevices in the future.For two-dimensional materials with excellent mechanical properties,applying strain is a simple and direct method of regulation.Although some experimental progress has been made in the study of the performance of ReSe₂ under local strain,the effect of continuous and uniform strain application on the optical and electrical properties of ReSe₂ remains to be clarified.In this paper,ReSe₂ was prepared by mechanical peeling method,and the optical and electrical properties of uniaxial strained ReSe₂ were studied by bending flexible substrate.The study found that in terms of optical properties,the fluorescence spectrum of ReSe₂ showed a red-shift and blue-shift trend with continuous stretching and compression,corresponding to the corresponding decrease and increase of its band gap under strain.In terms of electrical properties,ReSe₂has a significant piezoresistive effect,and its conductance increases with increasing tensile strain and decreases with increasing compressive strain.It is expected to design new electronic and optoelectronic devices based on ReSe₂ by adjusting the energy band structure to broaden its application fields.?2?The effect of strain application direction on the mechanical and electrical properties of ReSe₂.ReSe₂ has a twisted 1T phase structure,and its low lattice symmetry makes its optical and electrical properties significantly different along different crystallographic directions in the plane.In this paper,by applying tensile strain along different crystal directions in the ReSe₂ plane,the relationship between the mechanical and electrical properties of ReSe₂ and the direction of strain application is studied.The study found that the force-electric response factor when tensile strain is applied along its b-axis direction is 4.29 times that of its vertical direction.At the same time,the fluorescence spectrum changes when tensile strain is applied in two directions are observed.The results show that the effect of strain applied in the b-axis crystal direction on the energy band structure is greater than that in the vertical direction.The modulation of the band gap caused by the strain applied in the direction results.This anisotropic piezoresistive response is expected to enable ReSe₂ to be used in the field of multi-dimensional strain sensing.