In Situ Loading of ZnS on the PPF-3 Surface for Enhancing Nonlinear Optical Performance

In recent years, with the rapid development of ultrastrong and ultrafast lasers, it has become essential to develop new materials with excellent nonlinear optical (NLO) properties. Porphyrin-based metal-organic frameworks (MOFs) have great potential for application in the field of NLO due to their large conjugated structure and good stability. As a typical porphyrin-based MOF, porphyrin paddle-wheel framework-3 (PPF-3) has been prepared and applied in the fields of catalysis and sensing, yet the investigation of PPF-3 in NLO remains unexplored. In this study, the ZnS/PPF-3 composite was successfully prepared using a solvent thermal method to in situ load ZnS on the surface of PPF-3. Utilizing the Z-scan technique, the NLO properties of ZnS, PPF-3, and ZnS/PPF-3 composite were investigated under different input energy intensities. ZnS/PPF-3 composite material exhibits significantly enhanced NLO properties, with the third-order nonlinear absorption coefficient (β_eff) of up to 7.00 × 10^-10 m/W and a limiting threshold as low as 1.52 J/cm², indicating its promising application potential value in the field of optical limiting. To enhance the practical utility, the ZnS/PPF-3/PVA film was prepared via the drop-casting method, achieving a maximum β_eff of 5.00 × 10^-8 m/W. The smaller optical bandgap of ZnS/PPF-3 and electron transfer from PPF-3 to ZnS are the key factors that enable the ZnS/PPF-3 composite to a superior NLO performance.