Perylene Diimides (PDI) with Electronic Donor Core-Substituted Structures for Application of Solar Cell Materials by Theoretical Study (Showing PCE > 18.7%).

Five novel unfused non-fullerene acceptors were rationally designed via molecular engineering of a benchmark PDI-based molecule, achieving predicted power conversion efficiencies (PCEs) exceeding 18.7%. Comprehensive theoretical investigations employing density functional theory (DFT) and time-dependent DFT (TD-DFT) with the 6-31G(d, p) basis set elucidated the planarity of molecular geometries, molecular electrostatic potential (MEP) distributions, excitation energies, light-harvesting efficiencies, molar absorption coefficients, binding energies, density of states, and transition density matrices. The tailored structures exhibit strong optical absorption in the 589-618 nm range and favorable ealectronic transitions, as demonstrated by UV-Vis spectral simulations and transition density matrix analyses. Enhanced photovoltaic characteristics were observed, including reduced hole reorganization energies (as low as -0.26 eV, compared to 0.30 eV for the reference PDI), optimal open-circuit voltages (V_oc) between - 1.32 and 1.54 eV, and improved charge injection capabilities. These advances are anticipated to translate into superior photovoltaic performance in polymer solar cells (PSCs), with the simulated PCE values surpassing those of the experimentally reported parent molecule. Collectively, these results highlight the significant promise of the newly designed acceptors for next-generation PSC technologies.