2D-Conjugated Porphyrin-Based MOF/Graphene Oxide Heterostructures for Enhancing Nonlinear Optical Performance.

Two-dimensional (2D) conjugated metal-organic framework (MOF)-based heterostructures have attracted significant attention in third-order nonlinear optical (NLO) applications. However, the preparation of conjugated MOF heterostructures poses a significant challenge due to strong interlayer π-π stacking interactions. Herein, we report the fabrication of 2D porphyrin-based MOF (CuTCPP) thin films grown on graphene oxide (GO) via a liquid-phase epitaxy (LPE) layer-by-layer (LBL) method, forming a CuTCPP@GO heterostructure with strong interfacial π-π interactions. The CuTCPP@GO composite is incorporated into a polydimethylsiloxane (PDMS) matrix to produce a flexible PDMS glass for practical optical limiting (OL) application, which exhibits excellent mechanical flexibility and optical transparency while retaining the nonlinear optical functionality. The resulting CuTCPP@GO/PDMS exhibits dramatically enhanced OL performance with a nonlinear absorption coefficient of 3.3 × 10-9 m·W-1 and a lower OL threshold of 0.74 J·cm-2 than those of its individual components, attributed to the synergistic combination of extended π-conjugation and efficient interfacial charge transfer. This study provides a blueprint for the rational design of high-performance optical limiting materials through precise interfacial engineering and highlights the untapped potential of 2D MOF/graphene oxide heterostructures in nonlinear optical and optoelectronic applications.