ABSTRACT Covalent organic frameworks (COFs) are emerging as promising materials for nonlinear optical (NLO) research owing to their π‐conjugated architectures, structural tunability, and high chemical stability. This study employed the spatial self‐phase modulation (SSPM) technique to systematically investigate the third‐order NLO characteristics of anthraquinone‐based donor‐acceptor type COF, 2,6‐diaminoanthraquinone–1,3,5‐triformylphloroglucinol (DAAQ–TFP). The high values of nonlinear refractive index (n 2 = 4.3677 × 10 −5 cm 2 /W), single‐layer nonlinear electric susceptibility (χ (3) = 5.14 × 10 −9 esu) were evaluated and validated by theoretical estimation using Miller's rule. Furthermore, density functional theory (DFT) calculations of the electronic structure show that the effective nonlinear optical response of the COF is attributable to its donor‐acceptor moieties, which promote efficient charge transfer resulting in high nonlocal optical response. Finally, the applicability of this material in a photonic diode configuration is demonstrated by constructing a novel COF/CeO 2 hybrid structure, which connects its NLO response to device‐related functionality. This combined experimental–theoretical study provides fundamental insights into the NLO properties of COFs and establishes DAAQ–TFP COF as a potential candidate for future photonic device applications.
Dey et al. (Fri,) studied this question.