In an effort to gain a comprehensive picture of the interfacial states in bulk heterojunction solar cells, we provide a combined experimental–theoretical analysis of the energetics and dynamics of low-lying electronic charge-transfer (CT) states in donor:acceptor blends with a large frontier orbital energy offset. By varying the blend composition and temperature, we unravel the static and dynamic contributions to the disordered density of states (DOS) of the CT-state manifold and assess their recombination to the ground state. Namely, we find that static disorder (conformational and electrostatic) shapes the CT DOS and that fast nonradiative recombination crops the low-energy tail of the distribution probed by external quantum efficiency (EQE) measurements (thereby largely contributing to voltage losses). Our results then question the standard practice of extracting microscopic parameters such as exciton energy and energetic disorder from EQE.

中文翻译：

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供体低电荷转移激发态的命运：具有大能量偏移的受体混合物

为了全面了解块状异质结太阳能电池的界面态，我们提供了供体：受体共混物中低位电子电荷转移（CT）态的能级和动力学的组合实验-理论分析。大边界轨道能量偏移。通过改变共混物的成分和温度，我们揭示了对CT状态歧管的无序状态密度（DOS）的静态和动态影响，并评估了它们重新组合为基态的情况。即，我们发现静电无序（构象和静电）影响了CT DOS，而快速的非辐射复合则裁剪了通过外部量子效率（EQE）测量所探测到的分布的低能量尾部（从而极大地造成了电压损耗）。