Understanding the degradation mechanisms of printed bulk‐heterojunction (BHJ) organic solar cells during operation is essential to achieve long‐term stability and realize real‐world applications of organic photovoltaics. Herein, the degradation of printed organic solar cells based on the conjugated benzodithiophene polymer PBDB‐T‐SF and the nonfullerene small molecule acceptor IT‐4F with 0.25 vol% 1,8‐diiodooctane (DIO) solvent additive is studied in operando for two different donor:acceptor ratios. The inner nano‐morphology is analyzed with grazing incidence small angle X‐ray scattering (GISAXS), and current–voltage (I–V) characteristics are probed simultaneously. Irrespective of the mixing ratio, degradation occurs by the same degradation mechanism. A decrease in the short‐circuit current density (J_SC) is identified to be the determining factor for the decline of the power conversion efficiency. The decrease in J_SC is induced by a reduction of the relative interface area between the conjugated polymer and the small molecule acceptor in the BHJ structure, resembling the morphological degradation of the active layer.

中文翻译：

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在Operando中跟随具有非富勒烯小分子受体的印刷有机太阳能电池中结构演化引起的降解

了解印刷大体积异质结（BHJ）有机太阳能电池在运行过程中的降解机理对于实现长期稳定性和实现有机光伏的实际应用至关重要。在本文中，针对两种不同的操作，研究了基于共轭苯并二噻吩聚合物PBDB-T-SF和具有0.25 vol％1,8-二碘辛烷（DIO）溶剂的非富勒烯小分子受体IT-4F的印刷有机太阳能电池的降解供体：受体比例。通过掠入射小角X射线散射（GISAXS）分析内部纳米形态，并同时探测电流-电压（IV）特性。不管混合比例如何，通过相同的降解机理都会发生降解。短路电流密度降低（J _SC）被确定为功率转换效率下降的决定因素。在减少Ĵ _SC通过减少所述共轭聚合物和在BHJ结构的小分子受体之间的相对界面区域的诱导，类似活性层的形态的劣化。