Synergistic Enhancement of Nonlinear Optical Limiting via In-Situ Confined Carbon Nanodots in Metal-Porphyrinic Framework Thin Film

Abstract

Electron donor-acceptor (D-A) complexes are emerging as promising candidates for the development of effective nonlinear optical limiting (OL) materials but their preparation still remains challenging. Herein, we reported an electron D-A OL device based on a metal-porphyrinic framework thin film loaded with carbon nanodots (CDs). The composite film was prepared by impregnating porous PIZA-1 MOF film with o-phenylenediamine precursor and subsequent in-situ conversion of the precursor into CDs via laser irradiation. The resulting o-CDs@PIZA-1 thin film exhibits superior OL performance with a lower OL threshold of 2.21 J/cm² and a higher nonlinear absorption coefficient of 3.1 × 10⁻⁶ m•W⁻¹ compared to the pristine PIZA-1 thin film. This enhancement is mainly attributed to energy transfer/photoinduced electron transfer (ET/PET) of the porphyrin group and the confined CDs. Density functional theory (DFT) calculation reveals significant electronic interactions between the PIZA-1 moiety and CDs, with electron transfer pathways facilitating charge transport and optimizing the overall performance. This study proposes a novel MOF-nanocomposite strategy that effectively incorporates CDs into a solid matrix, enabling the preparation of high-performance OL materials ready for device integration and offering a viable route toward practical applications.