As the power conversion efficiency of organic photovoltaic has been dramatically improved to over 18%, achieving long-term stability is now crucial for applications of this promising photovoltaic technology. Among the high-efficiency systems, most are using BTP-4F and its analogs as acceptors. Herein, we determine the thermal transition temperatures (T_g) of seven BTP analogs to develop a structure-T_g framework. Our results point out an unresolved molecular design conundrum on how to simultaneously achieve high performance and intrinsic stability with BTP-based acceptors. We also show that PC₇₁BM has miscibility above the percolation threshold in PM6 and can maintain local charge percolation and improved stability in ternary devices. However, PC₇₁BM is not miscible with BTP-C3-4F and unfavorable vertical gradients that develop during aging still degrade performance. This points to a second thermodynamic conundrum. A compound with differential miscibility in the donor polymer can only impact percolation, and a compound with differential miscibility with the BTP only impacts diffusion.

由于有机光伏的功率转换效率已显着提高至 18% 以上，因此实现长期稳定性对于这种有前途的光伏技术的应用至关重要。在高效系统中，大多数使用 BTP-4F 及其类似物作为受体。在此，我们确定热转变温度（Ť_克7 BTP类似物），以开发出结构- Ť_克框架。我们的结果指出了一个未解决的分子设计难题，即如何使用基于 BTP 的受体同时实现高性能和内在稳定性。我们还表明 PC ₇₁BM 在 PM6 中具有高于渗透阈值的混溶性，并且可以保持局部电荷渗透并提高三元器件的稳定性。然而，PC ₇₁ BM 与 BTP-C3-4F 不混溶，老化过程中产生的不利垂直梯度仍会降低性能。这指向第二个热力学难题。在供体聚合物中具有不同混溶性的化合物只会影响渗透，而与 BTP 具有不同混溶性的化合物只会影响扩散。