High performance all-polymer solar cells enabled with solvent and solid dual additives

Abstract

Morphology optimization of a photoactive layer has a crucial role in fabricating high-performance polymer solar cells (PSCs). If an active layer is cast from solution, then the unique properties of the donor and acceptor materials often lead to either excessive or insufficient phase separation, which adversely affect the performance of the device. Specifically, all-polymer solar cells (all-PSCs) introduce an added complexity in terms of morphology regulation due to the inherently flexible and entangled nature of polymer chains. In this work, we first introduced 3,5-dichloroanisole (DCA) as a solid additive, known for its good crystallinity and volatility, to refine the active-layer morphology in all-PSCs. Then, we combined 1-chloronaphthalene (CN) and DCA as dual additives, which effectively optimized the morphology of all-polymer blends. This combination favored charge transport and minimized charge recombination, leading to a higher fill factor across various systems. Notably, a device based on PM6:PY-DT processed with this dual-additives approach achieved an impressive power conversion efficiency (PCE) of 17.42%, outperforming the control device without any additive, which showed a PCE of 14.34%. Besides, dual additives were applied in other systems, revealing their universality. This work not only took advantages of both solvent and solid additives, but also effectively improved the performance of all-PSCs.