Rational design and DFT-based study of non-fullerene acceptors for high-performance organic solar cells: End-cap and Core modifications for enhanced charge transfer

In this article, we reported the 64 newly designed non-fullerene acceptors (NFAs) using density functional theory (DFT) approaches combined with both central core and end-cap modification. We screened out five promising molecules among 64 molecules using four specific criteria and their structural as well as optoelectronic attributes were calculated. Using DFT techniques, we thoroughly examined the optical, electrical, and excited state characteristics such as energy gap, maximum absorption, excitation energy (E_x), and oscillator strength to evaluate the effects of various end-cap groups on different core architectures. Furthermore, we paired the most promising NFAs with the P3HT polymer donor to generate donor-acceptor interfaces, and we examined the open circuit voltage (V_oc) and rate of charge transfer (CT) at these interfaces. The conclusions offer insightful advice and useful design guidelines for high-performance NFAs that have the potential to greatly increase solar devices' efficiency.