Tuning the electronic and photovoltaic properties of naphthalene diamine through molecular engineering with efficient...

Non-fullerene-based organic solar cells (NF-OSCs) have emerged as promising photovoltaic systems owing to their tunable optoelectronic properties and enhanced power conversion efficiencies. Currently, three series of naphthalene-1,5-diamine (NDA)-based compounds(NBT1-NBT4, NBT5-NBT8, and NBT9-NBT12) featuring an A1-π1-A2-π2-A2-π1-A1 configuration were rationally designed through terminal modifications with thiophene linkers, malononitrile (MN)-based and benzothiophene (BT) based acceptor units. Quantum chemical calculations were performed at the MPW1PW91/6-311G(d, p) level to investigate their electronic, optical, and photovoltaic characteristics. Comprehensive analyses, including frontier molecular orbitals (FMOs), global reactivity parameters (GRPs), density of states (DOS), UV-Vis absorption spectra, transition density matrix (TDM), electron-hole distribution, and open-circuit voltage (V_oc), were conducted to evaluate their performance. The incorporation of different electron-withdrawing terminal acceptors effectively reduced the energy gap (2.641-2.323 eV) and broadened the absorption spectra across the visible region (534.484-638.238 nm). Comparable V_oc values were obtained through HOMO_PTB7-LUMO_acceptor estimation, indicating favorable energy-level alignment for charge transfer. Among the designed chromophores, NBT12 exhibited the smallest energy gap (2.323 eV), the highest absorption maximum (λ_max = 638.238 nm), and the most efficient intramolecular charge transfer, leading to efficient optoelectronic characteristics. These findings highlight the potential of NDA-based chromophores, particularly NBT12, as efficient non-fullerene acceptor materials for high-performance organic solar cells.