Intrinsic non-radiative voltage losses in fullerene-based organic solar cells
Intrinsic non-radiative voltage losses in fullerene-based organic solar cells
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DOI：
10.1038/nenergy.2017.53
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发表时间：
2017-06-01
期刊：
影响因子：
56.7
通讯作者：
Vandewal, Koen
中科院分区：
文献类型：
--
作者：
Benduhn, Johannes;Tvingstedt, Kristofer;Vandewal, Koen
有机太阳能电池表现出接近传统光伏技术的外部量子效率和填充因子。然而，与吸收材料的光隙相比，它们的开路电压要低得多，这主要是由于存在显著的非辐射复合。在这里，我们研究了大量已发表和新材料组合的数据集，发现非辐射电压损失随着电荷转移态能量的增加而降低。这一观察结果是通过考虑非辐射电荷转移态衰变作为马库斯倒转状态下的电子转移来解释的，这是由共同的骨架分子振动模式促进的。我们的研究结果表明，非辐射电压损失和电子振动耦合之间存在内在联系，表明这些损失是不可避免的。因此，单结有机太阳能电池的功率转换效率的理论上限将降低到约25.5%，最佳光隙增加到（1.45-1.65）eV，即比最小非辐射电压损失的技术高出（0.2-0.3）eV。
Organic solar cells demonstrate external quantum efficiencies and fill factors approaching those of conventional photovoltaic technologies. However, as compared with the optical gap of the absorber materials, their open-circuit voltage is much lower, largely due to the presence of significant non-radiative recombination. Here, we study a large data set of published and new material combinations and find that non-radiative voltage losses decrease with increasing charge-transfer-state energies. This observation is explained by considering non-radiative charge-transfer-state decay as electron transfer in the Marcus inverted regime, being facilitated by a common skeletal molecular vibrational mode. Our results suggest an intrinsic link between non-radiative voltage losses and electron-vibration coupling, indicating that these losses are unavoidable. Accordingly, the theoretical upper limit for the power conversion efficiency of single-junction organic solar cells would be reduced to about 25.5% and the optimal optical gap increases to (1.45-1.65) eV, that is, (0.2-0.3) eV higher than for technologies with minimized non-radiative voltage losses.