Synergistically Facilitate Charge Dynamics and Suppress Energetic Disorder via Tailoring Solid Additive Substituents for Efficient Organic Solar Cells Over 21%

Abstract

Simultaneously minimizing energy loss and optimizing charge dynamics remains a central challenge for further boosting the photovoltaic performance of organic solar cells (OSCs). As a key parameter controlling charge generation, transport, and recombination kinetics, film morphology is also closely linked to energetic disorder and therefore plays a crucial role in determining non-radiative recombination. Herein, a series of halogenated thiazole units (2,4-2DCl, 2Br-4Cl, and 2,4-DBr) are rationally designed for the precise regulation of film morphology. Among these solid additives, 2,4-DBr exhibits moderate molecular interactions with PM6 and L8-BO, which not only suppress over-aggregation but also promote the formation of ordered packing with favorable interpenetrating network structure. Consequently, the PM6:L8-BO-based OSCs treated with 2,4-DBr achieve the higher efficiency of 19.65%, accompanied by reduced voltage loss, benefiting from enhanced and balanced charge mobilities as well as suppressed energetic disorder. More impressively, the 2,4-DBr treated D18-based ternary devices deliver a remarkable efficiency of 21.10%, with a certified efficiency of 20.93% by CPVT, which ranks among the best values reported so far. This work highlights the critical role of rational halogenation strategies for solid additives in optimizing film morphology, thus enhancing charge dynamics and suppressing energetic disorder of the active layer, thereby enabling high-performance OSCs.