Enhancement in Optical and Optoelectronic Properties of Fluorinated Non-Fused Ring Electron Acceptors for Efficient Organic Photovoltaics

Recent advancements in organic photovoltaic materials have propelled the development of high-efficiency organic solar cells (OSCs). In this study, we present the design and comprehensive theoretical investigation of a new class of fluorinated non-fused-ring electron acceptors (NFREAs), UHA1–UHA10, for next-generation OSCs. Using density functional theory, we systematically evaluated the structural, electronic, and optoelectronic properties and compared them with the synthetic reference UHAR molecule. We systematically examined the key performance metrics, including ionization potentials, electron density variations, reorganization energies (for both electrons and holes), charge-transfer dynamics, transition density matrices, and molecular electrostatic potentials. Compared to the reference molecule 412-6F (UHAR), the designed UHA series UHA1–UHA10 exhibits improved optical and optoelectronic characteristics, including narrower energy gaps (1.98–1.48 eV) and significantly red-shifted absorption maxima, extending up to 969.69 nm (vs. 719 nm for UHAR). Notably, UHA4, UHA5, UHA9, and UHA10 exhibit lower exciton binding energies, suggesting enhanced charge separation and transport compared to the UHAR molecule. Among these, UHA4 stands out with the highest hole reorganization energy, positioning it as a particularly promising candidate for efficient electron transport. These findings underscore the potential of strategic molecular engineering of NFREAs to drive the next generation of high-performance OSCs. Moreover, the designed UHA series may add valuable molecular diversity to the advanced photovoltaic materials, offering promising avenues for future solar energy applications.