Enhancing Efficiency and Stability through Halogenation of Dimerized Acceptors in Quasiplanar Heterojunction Organic Solar Cells

Improving the power conversion efficiency (PCE) and long-term stability are crucial for making organic solar cells (OSCs) commercially viable. Utilizing dimerized acceptors in quasi-planar heterojunction (Q-PHJ) architectures can significantly improve the device stability. Halogenation, including fluorination and chlorination, is a highly effective strategy for enhancing the performance and ultimately improving the PCE of OSCs with nonfullerene acceptors (NFAs). In this study, the impact of halogenation on photovoltaic properties was investigated by constructing three dimerized small acceptors with diverse halogenated end-groups. The chlorinated dimerized acceptor dBTIC2Cl-V-HD achieves the highest PCE of 17.22% and T-80 lifetime of 2350h in Q-PHJ devices, surpassing both performance and stability of dBTIC2F-V-HD and dBTIC-V-HD. The results indicate that different halogen atoms have varying influences on material properties, and employing a chlorinated dimerized acceptor is an effective strategy for enhancing photovoltaic performance and stability, making them suitable for future commercial applications.