Enhancing Reproducibility in Organic Solar Cell Fabrication via Static Sequential Deposition with Cross-Linked Polymer Donor and Nonfullerene Acceptor

Abstract

The key to developing highly efficient organic solar cells (OSCs) hinges on crafting a photoactive layer with a bulk heterojunction (BHJ) structure. In this study, we fabricated a BHJ via sequential deposition (SqD), employing a PM6 polymer and Y6 small molecules as the donor and acceptor materials, respectively. Renowned for their pivotal roles in boosting the device performance, PM6 and Y6 have garnered significant attention among researchers. To address challenges associated with SqD techniques, such as achieving uniform coverage and establishing interfacial compatibility between layers, our approach (referred to as XSqD) involves depositing a cross-linked PM6 donor layer, followed by a Y6 acceptor layer, utilizing a static coating method and a good solvent. An azide-functionalized small molecule is employed to cross-link the PM6 polymer. Notably, the exposure of the PM6 polymer to the cross-linker under ultraviolet light and thermal annealing induces preferential cross-linking, resulting in the formation of a stable polymer network that effectively locks the internal morphology of the active layer without compromising its optical or electrical properties. OSCs fabricated via XSqD demonstrated enhanced power conversion efficiency and reproducibility compared with OSCs prepared using SqD with un-cross-linked PM6.