Boosting the performance of ternary solar cells by fine-tuning the distribution of the third component

• The localized deposition strategy dramatically enhances the energy transfer efficiency, increasing it from 38.26 % to 66.52 %. • For the first time, we have achieved quantitative analysis of the third component’s distribution in both lateral and vertical directions. • By employing the localized deposition strategy, we significantly improved the PCE to 18.69 % in PM6:PY-DT-based OSCs . Ternary organic solar cells (T-OSCs) utilizing energy transfer can enhance light absorption efficiency, thereby significantly improving power conversion efficiency (PCE). However, the uncontrollable distribution of the third component results in low energy transfer efficiency ( E FRET ). To address this, we proposed a localized deposition strategy for establishing a bulk heterojunction with a controlled distribution of the third component, denote as CD-HJ, wherein the energy donor is embedded within the energy acceptor phase. Meanwhile, for the very first time, we have combined experimental characterization with simulation and image processing to achieve a groundbreaking quantitative analysis of the third component distribution. Taking for PM6:PY-DT:IBC-F blend for instance, the device based on CD-HJ structure increases the proportion of IBC-F within the PM6 phase from 28.1 % to 80.6 % compared to the device based on BHJ. The optimized distribution of IBC-F boosted the E FRET from 38.26 % to 66.52 %. Consequently, the device based on CD-HJ structure achieved a PCE of 18.69 %.