Covalent functionalization of Sb₂S₃ with poly(N-vinylcarbazole) for solid-state broadband laser protection

An optimized complex multi-component nanomaterial system would help greatly enhance the optical limiting performance and applicability of 2D nanomaterials. By using antimony sulfide-[S-1-dodecyl-S'-(α,α'-dimethyl-α''-acetic acid)trithiocarbonate] (Sb₂S₃-DDAT) as a reversible addition fragmentation chain transfer (RAFT) agent, a highly soluble poly(N-vinylcarbazole)-covalently modified Sb₂S₃ (Sb₂S₃-PVK) was synthesized in situ and embedded into a non-optically active poly(methylmethacrylate) (PMMA) matrix producing a PMMA-based film with good optical quality. In contrast to both the Sb₂S₃/PMMA and Sb₂S₃:PVK blends/PMMA films, the Sb₂S₃-PVK/PMMA film exhibits more superior optical limiting performance. After annealing in N₂ at 200 °C for 30 minutes, the achieved nonlinear absorption coefficient and limiting threshold are changed from 411.79 cm GW^-1 and 1.93 J cm^-2 at 532 nm and 242.79 cm GW^-1 and 4.17 J cm^-2 at 1064 nm before annealing to 478.04 cm GW^-1 and 1.70 J cm^-2 at 532 nm and 520.92 cm GW^-1 and 1.40 J cm^-2 at 1064 nm after annealing, respectively. These advantages make Sb₂S₃-PVK one of the potential promising candidates for a broadband laser protector in both the visible and near-infrared ranges.