Tuning the Photophysical Properties of Acceptor–Donor–Acceptor Di-2-(2-oxindolin-3-ylidene) Malononitrile Materials via Extended π–Conjugation: A Joint Experimental and Theoretical Study

Many optoelectronic applications require organic semiconductor (OSC) materials with high electron affinity. In this work, a series of novel acceptor–donor–acceptor (A–D–A) low-lying LUMO energy levels were designed and characterized. strategy, two acceptor dyes, bis-isatin di-2-(2-oxindolin-3-ylidene) malononitrile, connected by various π–bridges (benzene ring, benzo[c][1,2,5]thiadiazole, monothiophene, trithiophene). We varied the length π–conjugation central core linkage position (4- vs. 6-position phenyl ring) to investigate effect on optical electrochemical properties materials. performed density functional theory (DFT) time-dependent DFT (TD–DFT) studies gain insight into dyes’ electronic determining levels. Our findings demonstrate that increasing strength core, wavelength longest absorption maximum as well their respective extinction coefficients are enhanced, which results in band-gap reduction either lowering and/or raising HOMO level molecules. The potential practical utility these electron-transport for perovskite solar cells (PSCs) has been demonstrated.