Tuning the blend composition is an essential step to optimize the power conversion efficiency (PCE) of organic bulk heterojunction (BHJ) solar cells. PCEs from devices of unoptimized donor:acceptor (D:A) weight ratio are generally significantly lower than optimized devices. Here, two high‐performance organic nonfullerene BHJ blends PBDB‐T:ITIC and PBDB‐T:N2200 are adopted to investigate the effect of blend ratio on device performance. It is found that the PCEs of polymer‐polymer (PBDB‐T:N2200) blend are more tolerant to composition changes, relative to polymer‐molecule (PBDB‐T:ITIC) devices. In both systems, short‐circuit current density (J_sc) is tracked closely with PCE, indicating that exciton dissociation and transport strongly influence PCEs. With dilute acceptor concentrations, polymer‐polymer blends maintain high electron mobility relative to the polymer‐molecule blends, which explains the dramatic difference in PCEs between them as a function of D:A blend ratio. In addition, polymer‐polymer solar cells, especially at high D:A blend ratio, are stable (less than 5% relative loss) over 70 d under continuous heating at 80 °C in a glovebox without encapsulation. This work demonstrates that all‐polymer solar cells show advantage in operational lifetime under thermal stress and blend‐ratio resilience, which indicates their high potential for designing of stable and scalable solar cells.

中文翻译：

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对掺混比具有高耐受性的热稳定全聚合物太阳能电池

调整共混物组成是优化有机体异质结（BHJ）太阳能电池的功率转换效率（PCE）的重要步骤。未优化供体：受体（D：A）重量比的设备的PCE通常明显低于优化设备。在这里，采用两种高性能有机非富勒烯BHJ共混物PBDB-T：ITIC和PBDB-T：N2200来研究混合比例对器件性能的影响。发现与聚合物分子（PBDB-T：ITIC）装置相比，聚合物-聚合物（PBDB-T：N2200）共混物的PCE更能耐受成分变化。在这两个系统中，短路电流密度（J _sc）与PCE密切相关，表明激子的解离和迁移强烈影响PCE。在受主浓度较低的情况下，聚合物-聚合物共混物相对于聚合物-分子共混物可保持较高的电子迁移率，这解释了它们之间的PCE随D：A共混比的变化而显着不同。此外，聚合物-聚合物太阳能电池，特别是在高D：A混合比的情况下，在不密封的情况下，在手套箱中于80°C连续加热下，在70 d内可保持稳定（相对损耗小于5％）。这项工作表明，全聚合物太阳能电池在热应力和混合比弹性下的使用寿命方面具有优势，这表明它们在设计稳定和可扩展的太阳能电池方面具有很高的潜力。