Photo-Induced Charge Transfer of Fullerene and Non-Fullerene Conjugated Polymer Blends via Ab Initio Excited-State Dynamics
Photo-Induced Charge Transfer of Fullerene and Non-Fullerene Conjugated Polymer Blends via Ab Initio Excited-State Dynamics
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DOI：
10.1021/acs.jpcc.2c01640
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发表时间：
2022-07-14
影响因子：
3.7
通讯作者：
Kilin, Dmitri
中科院分区：
文献类型：
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作者：
Alesadi, Amirhadi;Xia, Wenjie;Kilin, Dmitri
有机共轭聚合物（CPs）由于其独特的可调机械性能和光电性能而成为有机光伏（OPV）器件的理想材料。在过去的十年中，窄带隙CP作为受体单元的共混物的光电性能在很大程度上得到了优化，这导致了OPV技术的显着进步。然而，它们的功率转换效率仍然低于它们的有机对应物（即，硅），限制了它们的实际使用。在这项研究中，我们采用从头算分子动力学来探索基于二酮基吡咯并吡咯的聚合物作为与非富勒烯（即，ITIC）和富勒烯（即，PCBM）受体单元。选择性光激发引起的载流子动力学结果表明，空穴密度在空间的重新分布比电子弛豫快得多。我们跟踪电荷载流子随时间的弛豫速率，其中电子和空穴速率之间的差的导数意味着零电压下的电流密度。这可用于表征与不同受体单元共混的CP的CT性能。弛豫速率结果表明，CP与ITIC的共混物保证了更好的PV性能，说明当前的计算方法为确定OPV器件的本体异质结的电子性能打开了大门，并缩小了潜在的供体-受体候选者的列表。
Organic conjugated polymers (CPs) are promising candidates for organic photovoltaic (OPV) devices due to their unique tunable mechanical and optoelectronic performance. Over the last decade, optoelectronic properties of narrow band gap CPs as a blend with acceptor units are largely optimized, which leads to noticeable progress in OPV technology. However, their power conversion efficiency is still lower than their organic counterparts (i.e., silicon), limiting their practical usage. In this study, we employ ab initio molecular dynamics to explore photo-induced charge transfer (CT) of the diketopyrrolopyrrole-based polymer as a blend with non-fullerene (i.e., ITIC) and fullerene (i.e., PCBM) acceptor units. The results of charge carrier dynamics induced by selected photoexcitation show that hole density redistribution in space is much faster than electron relaxation. We track the relaxation rates of charge carriers over time, where the derivative of the difference between the rate of electron and hole implies the current density at zero voltage. This can be utilized to characterize the CT performance of CPs blended with different acceptor units. Relaxation rate results indicate that CP blend with ITIC promises a better PV performance, illustrating that the current computational approach opens the door to determine bulk heterojunctions' electronic performance for OPV devices and narrowing down the list of potential donor-acceptor candidates.