Polymer functionalized antimony sulfide quantum dots for broadband optical limiting.

The rapid development of zero-dimensional quantum dots-based nanotechnology has motivated the design and synthesis of novel nano-functional materials for optoelectronic and photonic devices in recent years. Antimony sulfide (SbS) quantum dots (SQDs), with an average diameter of 3.22 nm, were prepared a top-down liquid ultrasonication exfoliation technique. Highly soluble poly(-vinylcarbazole)-covalently functionalized SQDs (SQDs-PVK) were synthesized by reversible addition fragmentation chain transfer polymerization, and embedded into a non-optically active poly(methylmethacrylate) (PMMA) matrix giving the SQDs-PVK/PMMA film. The annealed SQDs-PVK/PMMA film showed exceptional nonlinear optical performance, with large nonlinear absorption coefficients of 713.71 cm GW at 532 nm and 913.60 cm GW at 1064 nm, and small limiting thresholds of 1.44 J cm at 532 nm and 1.08 J cm at 1064 nm. These advantages make SQDs-PVK one of the promising candidates for a broadband optical limiter in both the near-infrared and visible ranges.