Dissecting the electron mobility and physical mechanisms of Y series acceptors with central hybridization substitutions

Inspired by the high-performance acceptor CH17 with a reported efficiency of 18.13 %, this study designs three novel π-conjugated non-fullerene acceptors (CH2H, CH2CH3, and CH2OCH3) by central hybridization based on the central unit and end unit 2-(6,7-difluoro-3-oxo-2,3-dihydro-1H-cyclopental[b]naphthalen-1-ylidene) malononitrile (NINCN-2F). A comprehensive quantum chemical investigation is conducted to assess photophysical properties, charge transport behavior, and molecular configurations. Results indicate that central unit hybridization effectively narrows the energy gap ( Δ L-H ) and singlet–triplet energy difference ( △ E ST ), enhances the absorption maximum ( λ max ) and electron mobility ( µ e ), and improves overall photophysical and photoexcitation characteristics. Among the designed molecules, CH2OCH3 demonstrates optimal performance, exhibiting the smallest Δ L-H (1.85 eV), △ E ST (0.4994 eV), the largest λ max (749.79 nm), and the highest µ e (0.3597 cm 2 /(V·s)). This study confirms that structural tailoring of the central moiety serves as a viable strategy to enhance optoelectronic performance, charge transfer ability, and photovoltaic properties of NFAs.