Photophysical Mechanism and Spectral Regulation of Asymmetric Acceptors Based on a Benzotriazine Central Core

Non ‐ fullerene acceptors (NFAs) have tunable molecular structures and can optimize physical properties through improving chemical modifications, featuring high light absorption coefficients and a narrow energy gap. The photophysical mechanisms and excited‐state properties of NFAs (H‐2CH ₃ and H‐2OCH ₃ ) topologies are investigated using quantum chemical simulations to examine how core substitution with methyl (─CH ₃ ) and methoxy (─OCH ₃ ) groups affects key molecular parameters. The results indicated that compared with the experimental molecule (H‐1 and H‐2F), the designed molecule H‐2OCH ₃ exhibited a smaller energy gap, a larger redshifted absorption wavelength, a lower singlet–triplet energy difference, lower radiation and internal conversion rates, and the highest electron mobility by inserting ─OCH ₃ groups into the core region. Therefore, the H‐2OCH ₃ derivative exhibits significantly improved theoretical optoelectronic properties, showing great potential for application in organic solar cells.