The WS2 quantum dot: preparation, characterization and its optical limiting effect in polymethylmethacrylate

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Tungsten disulfide (WS2) quantum dots (QDs) are synthesized via liquid exfoliation.
• WS2 QDs exhibit desirable surface energy for efficient fabrication.
• The nonlinear optical (NLO) properties of WS2 QDs are crucial for optical limiting applications.

Purpose of the Study:

• To fabricate ultra-small WS2 quantum dots (QDs).
• To investigate the nonlinear optical (NLO) properties of WS2 QD/polymethylmethacrylate (PMMA) composites.
• To evaluate the potential of WS2 QDs for optical limiting applications.

Main Methods:

• Direct liquid exfoliation of WS2 in N-methyl-2-pyrrolidone.
• Ultrasound-assisted fabrication followed by high-speed centrifugation (up to 10,000 rpm).
• Fabrication of WS2 QD/PMMA composites and NLO property measurement using nanosecond pulsed lasers at 532 and 1064 nm.

Main Results:

• Ultra-small WS2 QDs with a diameter of 2.4 nm were successfully synthesized.
• WS2 QD/PMMA composites demonstrated excellent nonlinear optical (NLO) properties.
• Lower onset thresholds (F_ON) and optical limiting thresholds (F_OL) were observed with increasing WS2 QD concentration.
• Higher two-photon absorption coefficient (β) was achieved with higher WS2 QD concentrations.

Conclusions:

• Direct liquid exfoliation is an effective method for producing WS2 QDs.
• WS2 QD/PMMA composites exhibit significant potential for optical limiting applications.
• The concentration of WS2 QDs directly influences the NLO performance of the composite material.