Are hot charge transfer states the primary cause of efficient free-charge generation in polymer:fullerene organic photovoltaic devices? A kinetic Monte Carlo study.
Are hot charge transfer states the primary cause of efficient free-charge generation in polymer:fullerene organic photovoltaic devices? A kinetic Monte Carlo study.
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DOI：
10.1039/c4cp01626b
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
Matthew L Jones;R. Dyer;N. Clarke;C. Groves
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文献类型：
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作者：
Matthew L Jones;R. Dyer;N. Clarke;C. Groves
动力学蒙特卡罗模拟被用来研究高能、‘热’离域电荷转移(HCT)态对施主：受主和混合：聚集体共混物的影响，后者与聚合物：富勒烯光伏器件有关。富勒烯聚集的增加被证明增强了电荷产生和短路器件电流-主要是由于聚集界面上的HCT态的产生增加。然而，预测HCT态的内部量子效率在50%范围内的情况并不对应于在实验中测量的HCT离域或电子迁移率。因此，这些数据表明，在某些聚合物：富勒烯OPV中，HCT态并不是高量子效率的主要原因。相反，有人认为，光谱学中所看到的快速电荷产生是由HCT态负责的，但能级的区域差异是长期、有效的自由电荷产生的原因。
Kinetic Monte Carlo simulations are used to examine the effect of high-energy, 'hot' delocalised charge transfer (HCT) states for donor:acceptor and mixed:aggregate blends, the latter relating to polymer:fullerene photovoltaic devices. Increased fullerene aggregation is shown to enhance charge generation and short-circuit device current - largely due to the increased production of HCT states at the aggregate interface. However, the instances where HCT states are predicted to give internal quantum efficiencies in the region of 50% do not correspond to HCT delocalisation or electron mobility measured in experiments. These data therefore suggest that HCT states are not the primary cause of high quantum efficiencies in some polymer:fullerene OPVs. Instead it is argued that HCT states are responsible for the fast charge generation seen in spectroscopy, but that regional variation in energy levels are the cause of long-term, efficient free-charge generation.