Identification of aggregated 2D cobalt tellurides using a spatial self-phase modulation technique

Area of Science:

• Materials Science
• Nanoscience
• Optical Physics

Background:

• Nonlinear optical (NLO) properties of 2D materials are crucial for advanced applications.
• Understanding solute-solvent interactions is key to controlling material dispersion and performance.
• Spatial Self-Phase Modulation (SSPM) is a sensitive technique for probing optical nonlinearities.

Purpose of the Study:

• To explore a novel application of SSPM for detecting solute-solvent interactions in 2D materials.
• To investigate the nonlinear optical susceptibility of 2D Co2Te3.
• To correlate changes in 2D material dispersion with solvent polarity using SSPM.

Main Methods:

• Utilized broadband optical absorption to characterize 2D Co2Te3.
• Employed spatial self-phase modulation (SSPM) with a CW laser.
• Analyzed the fine structure of SSPM patterns.
• Confirmed aggregation using in situ optical microscopy and UV-vis absorption spectroscopy.

Main Results:

• 2D Co2Te3 exhibits a high nonlinear optical susceptibility (χ(3) ~10^-9 esu).
• Increasing solvent polarity induces aggregation of 2D Co2Te3.
• SSPM patterns transition from type-I to type-II with increasing solvent polarity, indicating aggregation.

Conclusions:

• SSPM is a viable optical tool for identifying solvent-polarity-induced aggregation in 2D materials.
• The NLO response of 2D Co2Te3 is sensitive to its aggregation state.
• This work opens new avenues for characterizing and controlling 2D material suspensions.