Core-Linked Dimer Acceptors with Flexible Linker for High-efficiency and Robust Organic Solar Cells

Abstract

Oligomerized small molecular acceptors (OSMAs) have been applied to tackle the stability challenge of organic solar cells (OSCs) owing to their elevated glass transition temperatures, which can suppress the molecular diffusion and contribute to the stabilization of the device morphology. In this work, we designed and synthesized a core-connected OSMA, dPQx-F by integrating a flexible alkyl chain linker, which can regulate the solubility and crystallization properties.When incorporating dPQx-F to the D18:L8-BO system, it can not only facilitate the formation of the fibrous morphology, but also restrict the self-aggregation of the acceptor phase. As a result, the D18:L8-BO:dPQx-F can realize a remarkable efficiency of 20.06% with an outstanding thermal stability. After annealing at 65 ℃ for 550 h, it can still keep 85% of the original efficiency. This work presents an efficient approach to resolve the trade-off between the molecular structure, device performance and stability.