Initial Temperature Regulated Precursor Solution Assembly Enables High Performance Organic Solar Cells

Abstract

A critical challenge in optimizing the morphology of organic solar cell active layers lies in achieving precise control over the pre-aggregation behavior of donors and acceptors using simple and solution-processable parameters to construct an ideal microstructure. To address this issue, this study proposes a precursor-solution assembly strategy based on tuning the initial temperature of the blended solution to optimize the microstructure of PM6:L8-BO binary organic solar cell active layers. The results demonstrate that a moderate initial temperature (60 °C) effectively regulates the pre-aggregation behavior of the donor and acceptor, leading to an active layer with a smoother surface, more favorable phase separation, and better-coordinated molecular packing. Consequently, exciton dissociation and charge transport are facilitated, while recombination losses are suppressed. Ultimately, the PM6:L8-BO binary device achieves a high power conversion efficiency of 20.23 %, with significant improvements in both short-circuit current density and fill factor. This work establishes a clear structure–property relationship linking initial temperature, pre-aggregation behavior, thin-film microstructure, and device performance, thereby providing a novel strategy for morphology control and process optimization of high-performance organic solar cells.