High-efficiency ternary organic solar cells with non-fullerene small molecule acceptor N3 as the third component

To enhance the performance of organic solar cells (OSCs), a new ternary strategy was proposed. By introducing a non-fullerene small molecule acceptor N3 with a similar chemical structure to the main acceptor as the third component into the PM6:BTP-eC9 binary system, a high-efficiency ternary organic solar cell was prepared. As the third component, N3 enhances the light absorption of the active layer and thus facilitates the enhancement of J_SC. The good compatibility of N3 with BTP-eC9 allows the addition of N3 to optimize the active layer morphology, obtain a suitable phase separation, and form an alloy-like model with BTP-eC9 in the active layer, facilitating exciton dissociation, charge transport, and suppression of charge recombination. Finally, the optimal ternary device power conversion efficiency (PCE) based on PM6:BTP-eC9:N3 was improved from 17.22% to 18.54% for PM6:BTP-eC9 when 10% of N3 was added. The performance improvement is mainly attributed to the J_SC and FF enhancement. The experimental results indicate that the preparation of high-efficiency ternary organic solar cells by using derivatives with similar chemical structures as the third component is a simple and effective strategy.