Dual\nAdditive Strategy with Quasi-Planar Heterojunction\nArchitecture Assisted in Morphology Optimization for High-Efficiency\nOrganic Solar Cells

Achieving high-performance and stable\norganic solar cells (OSCs)\nremains a critical challenge, primarily due to the precise optimization\nrequired for active layer morphology. Herein, this work reports a\ndual additive strategy using 3,5-dichlorobromobenzene (DCBB) and 1,8-diiodooctane\n(DIO) to optimize the morphology of both bulk-heterojunction (BHJ)\nand quasi-planar heterojunction (Q-PHJ) based on donor D18 and acceptor\nBTP-eC9. The systematic results reveal that the dual additive strategy\nsignificantly promotes phase separation while inhibiting excessive\naggregation, which, in turn, improves molecular order and crystallization.\nAs a result, BHJ and Q-PHJ OSCs processed with dual additive DIO +\nDCBB achieve impressive power conversion efficiencies of 17.77% and\n18.60%, respectively, the highest reported values for dual additive-processed\nOSCs. The superior performance is attributed to improved charge transport\nand reduced recombination losses, as evidenced by higher short-circuit\ncurrent densities (<i>J</i><sub>SC</sub>) and fill factors\n(FF). Importantly, Q-PHJ OSCs processed with either DCBB or DIO +\nDCBB, in comparison to BHJ OSCs, exhibit exceptional shelf-stability,\nmaintaining 80% of their initial power conversion efficiency after\n2660 and 2193 h, respectively. These findings underscore the potential\nof dual additive strategies to advance the development of stable,\nhigh-efficiency OSCs suitable for large-area fabrication, marking\na significant step forward in renewable energy technology.