The simultaneous improvement of power conversion efficiency (PCE) and thermal stability is a critical scientific challenge in advancing the commercial applications of polymer solar cells. To address this challenge, we successfully designed and synthesized a dumbbell-shaped dimeric acceptor, DT19, and incorporated it as a third component into the PM1:BTP-eC9 system. This ternary strategy demonstrated a synergistic enhancement of the PCE and thermal stability of the host binary system. In particular, the PM1:BTP-eC9:DT19 system maintained a PCE of over 90% even after heating at 120 °C for 200 hours. Additionally, the dimer-doping ternary strategy exhibited excellent generality for the other four Y-series systems and outperformed ternary systems containing alloy-like acceptors in terms of thermal stability. It is because DT19, with its hinge-like structure, can form a semi-alloy acceptor with the host acceptor, leading to strong interchain entanglement with the polymer donor, thus overcoming phase separation and excessive aggregation under thermal stress. This new type of dimeric material, which can synergistically enhance the device efficiency and thermal stability of active layers, presents promising application prospects.
Figure 1. (a) Chemical structure formula of DT19; (b) Normalized PCE of corresponding blends with different third components before and after heating at 120 °C for 200 hours; (c) Schematic diagram of the changes in active layer morphology before and after thermal stress for the ternary alloy system and the ternary semi-alloy system investigated in this work.
This work was financially supported by the National Natural Science Foundation of China (NSFC) (Grant No. 52061135206 and 22279094) and the Fundamental Research Funds for the Central Universities. We thank the Core Facility of Wuhan University for the optical microscope and AFM measurements.
Original link: https://doi.org/10.1002/adma.202302592
