Prediction of Second-Order Nonlinear Optical Properties of D–π–A Compounds Containing Novel Fluorene Derivatives: A Promising Route to Giant Hyperpolarizabilities

Abstract

Herein, first attempt has been made to utilize fluorene-based dye-sensitized solar cell (DSSCs) dye JK-201 as potential nonlinear optical (NLO) material and for the theoretical designing of novel NLO chromophores JK-D1–JK-D12. DFT/TDDFT calculations were performed to compute the effect of π-linkers and acceptors-steered modulation on electronic, photophysical and NLO properties of JK-201 and JK-D1–JK-D12. Results illustrate that computed λmax (484.74 nm) and experimentally calculated λmax (481 nm) of JK-201 was found in good agreement. Maximum red shifted absorption spectrum was observed in JK-D12 with 599.38 nm. JK-D1–JK-D12 showed narrow energy gap and broader absorption spectrum as compared to JK-201. NBO analysis confirmed the formation of charge separation state due to robust range of electrons/charge transfer from donor to acceptor via π-bridge. Giant NLO response was observed in all compounds. Particularly, JK-D12 displayed surprisingly large 〈α〉 and βtot computed 1376.74 (a.u.) and 405,731.84 (a.u.) respectively. Although literature is flooded with D–π–A compounds investigated for their DSSCs properties, but research reports on their NLO properties and utilization as NLO materials are completely deserted. Our research will open new horizons to explore DSSCs materials for NLO applications. This theoretical framework also exposed that fluorene-substituted chromophores are excellent NLO candidates for modern hi-tech applications.