The best organic solar cells (OSCs) achieve comparable peak external quantum efficiencies and fill factors as conventional photovoltaic devices. However, their voltage losses are much higher, in particular those due to nonradiative recombination. To investigate the possible role of triplet states on the donor or acceptor materials in this process, model systems comprising Zn‐ and Cu‐phthalocyanine (Pc), as well as fluorinated versions of these donors, combined with C₆₀ as acceptor are studied. Fluorination allows tuning the energy level alignment between the lowest energy triplet state (T₁) and the charge‐transfer (CT) state, while the replacement of Zn by Cu as the central metal in the Pcs leads to a largely enhanced spin–orbit coupling. Only in the latter case, a substantial influence of the triplet state on the nonradiative voltage losses is observed. In contrast, it is found that for a large series of typical OSC materials, the relative energy level alignment between T₁ and the CT state does not substantially affect nonradiative voltage losses.

中文翻译：

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三重激发态对有机太阳能电池开路电压的影响

最好的有机太阳能电池（OSC）可达到与传统光伏设备相当的峰值外部量子效率和填充因子。但是，它们的电压损失要高得多，特别是由于非辐射复合而产生的电压损失。为了研究三重态在该过程中对供体或受体材料的可能作用，研究了包含Zn-和Cu-酞菁（Pc）以及这些供体的氟化形式以及C ₆₀作为受体的模型系统。氟化允许在最低能量三重态（T ₁）和电荷转移（CT）状态，而用Cu代替Zn作为Pcs中的中心金属会导致自旋轨道耦合大大增强。仅在后一种情况下，观察到三重态对无辐射电压损失的实质影响。相反，发现对于大量典型的OSC材料，T ₁和CT状态之间的相对能级对准基本上不会影响非辐射电压损耗。