Fabrication and nonlinear optical characterization of fluorinated zinc phthalocyanine covalently modified black phosphorus/PMMA films using the nanosecond Z-scan technique

Abstract

As one of the excellent and attractive building blocks, phthalocyanines (Pcs) exhibit outstanding electronic, optoelectronic and optical properties. It would thus be very interesting and challenging to covalently functionalize the well-known star material “2D black phosphorus (BP)” with Pcs. By using a newly synthesized zinc phthalocyanine-based diazonium salt, F₁₂PcZn–N₂⁺BF₄⁻, as the synthetic precursor, a novel F₁₂PcZn–BP nanohybrid material with a direct covalent linkage between the PcZn complex and the BP nanosheets was synthesized and embedded into a poly(methyl methacrylate) (PMMA) matrix producing a PMMA-based film with good optical quality. Compared to the BP/PMMA and F₁₂NH₂PcZn/PMMA films, the F₁₂PcZn–BP/PMMA film shows more superior nonlinear optical (including optical limiting) properties. After annealing in N₂ at 200 °C for 30 minutes, the achieved nonlinear absorption coefficient (β_eff) and limiting threshold are changed from 177.10 cm GW⁻¹ and 0.72 GW cm⁻² for the non-annealed F₁₂PcZn–BP/PMMA film to 263.47 cm GW⁻¹ and 0.61 GW cm⁻², respectively.