In Situ Nonlinear Optical Absorption Response during Electrochemically Controlled ReS₂ Surface Oxidation

Area of Science:

• Materials Science
• Chemistry
• Physics

Background:

• Surface functionalization of 2D semiconductors precisely tunes electronic and optical properties.
• Exploring oxidation-dependent nonlinear optical properties is limited by the lack of in situ characterization techniques.

Purpose of the Study:

• To develop an in situ technique for controlling and monitoring oxidation-mediated nonlinear optical properties of 2D semiconductors.
• To investigate the transition of nonlinear absorption in ReS2 during electrochemical oxidation.

Main Methods:

• Developed an electrochemical method for selective surface oxidation of ReS2.
• Integrated electrochemical oxidation with a Z-scan setup to create an in situ electrochemical Z-scan system.
• Utilized theoretical calculations (band alignment, density of states) to support experimental findings.

Main Results:

• Successfully controlled the surface oxidation of ReS2 electrochemically.
• Observed a transition in nonlinear absorption from two-photon absorption to saturable absorption with increasing oxidation.
• Demonstrated that ReS2's two-photon absorption decreases while ReO3's saturable absorption enhances.

Conclusions:

• The developed in situ electrochemical Z-scan technique is effective for controlling surface oxidation and monitoring nonlinear optical properties.
• This technique offers a simple, nondestructive approach for studying oxidation effects in 2D materials.
• The findings provide insights into tuning optoelectronic properties of 2D semiconductors through controlled oxidation.