Energy losses significantly reduce the open-circuit voltage among current state-of-the-art organic solar cells (OSCs), which limits the further enhancement of their power conversion efficiencies (PCEs). In this study, the bulk heterojunction blends of PM6 donor and halogenated nonfullerene acceptors (NFAs) display a trade-off between radiative energy losses, i.e., charge transfer state (CTS) radiative energy loss (ΔE_rad) and the loss associated with CTS formation from acceptor singlet excitons (ΔE_CT^EL). Similarly, a trade-off between ΔE_rad and the nonradiative energy loss (ΔE_nr) is found, reflecting a competition in radiative and nonradiative charge recombination pathways. Further, the energy levels of relaxed CTS (E_CT^EL) are shown to exhibit dependence on morphologically induced energetic traps, suggesting that it should not be associated merely to blend constituents. Interestingly, these correlations extend even to thermally degraded devices considered herein. Accordingly, this work provides further understandings of energy losses relevant to overcome the current limitations concerning NFA-based OSC developments.

中文翻译：

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了解非富勒烯有机太阳能电池中的电荷转移状态和能量损失权衡

能量损失显着降低了当前最先进的有机太阳能电池 (OSC) 之间的开路电压，这限制了其功率转换效率 ( PCE )的进一步提高。在这项研究中，PM6 供体和卤化非富勒烯受体 (NFA) 的本体异质结混合物显示出辐射能损失，即电荷转移态 (CTS) 辐射能损失 ( ΔE _rad ) 和与 CTS 形成相关的损失之间的权衡来自受体单线态激子 ( ΔE _CT ^EL )。类似地，在ΔE _rad和非辐射能量损失 ( ΔE _nr) 被发现，反映了辐射和非辐射电荷重组途径的竞争。此外，松弛的 CTS ( E _CT ^EL )的能级显示出依赖于形态诱导的能量陷阱，表明它不应该仅仅与混合成分相关。有趣的是，这些相关性甚至扩展到这里考虑的热退化设备。因此，这项工作提供了对与基于 NFA 的 OSC 发展有关的当前限制相关的能量损失的进一步理解。