MoS₂ quantum dots chemically modified with porphyrin for solid-state broadband optical limiters

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Molybdenum disulfide quantum dots (MQDs) possess unique electronic and optical properties, making them suitable for nonlinear optical (NLO) applications.
• Functionalizing MQDs with optoelectronically active molecules like porphyrins can enhance their NLO performance.

Purpose of the Study:

• To synthesize a novel nanohybrid material by covalently functionalizing tetraphenylporphyrin (TPP) onto the surface of MQDs.
• To investigate the solid-state broadband nonlinear optical and optical limiting properties of the synthesized MQD-TPP nanohybrid.

Main Methods:

• Synthesis of MQD-TPP nanohybrid via covalent C-S linkage using TPP diazonium salts and MQDs.
• Encapsulation of the MQD-TPP nanohybrid into a poly(methyl methacrylate) (PMMA) matrix.
• Open-aperture Z-scan measurements at 532 nm and 1064 nm to evaluate NLO and optical limiting responses.

Main Results:

• The MQD-TPP/PMMA film demonstrated superior nonlinear optical and optical limiting responses compared to pristine MQDs/PMMA and TPP/PMMA.
• The nanohybrid achieved significant nonlinear coefficients (β_eff) of 1059.17 cm GW^-1 at 532 nm and 831.13 cm GW^-1 at 1064 nm.
• The lowest optical limiting (OL) thresholds were observed for MQD-TPP/PMMA, recorded at 1.62 J cm^-2 (532 nm) and 1.97 J cm^-2 (1064 nm).

Conclusions:

• The successful covalent functionalization of TPP onto MQDs creates a nanohybrid with enhanced broadband nonlinear optical properties.
• The MQD-TPP nanohybrid shows great potential for solid-state ultrafast optical applications, particularly in optical limiting.