Comprehensive investigation on two-photon absorption enhancement via excited-state charge transfer in terminal modified chalcone derivatives

Three chalcone derivatives with different terminal modifications (furan, biphenyl, pyrenyl) were designed and synthesized. The nonlinear optical (NLO) properties of chalcone derivatives were comprehensively analyzed by Z -scan, transient absorption spectroscopy and density functional theory (DFT). Owing to the cross-conjugated structure of acryl ketone, which divide the π-electron delocalization pathway into several relatively independent conjugated segments, and the intramolecular charge transfer (ICT) process can be precisely regulated. The combination of experimental data and theoretical simulation reveals the influence of the intramolecular charge transfer processes on the NLO properties. The charge transfer in excited states of the chalcone derivatives across the cross-conjugated structure enhances the absorption cross section of the two-photon induced excited state. The two-photon induced excited state absorption (TP-ESA) cross sections of the three chalcone derivatives reach ∼10⁻²⁰ m², making them strong candidates for nonlinear photonic devices and optical limiting applications.