Niklas Jens, Beaupré Serge, Leclerc Mario, Xu Tao, Yu Luping, Sperlich Andreas, Dyakonov Vladimir, Poluektov Oleg G
†Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States.
‡Department of Chemistry, Laval University, Quebec City, Quebec G1V 0A6, Canada.
J Phys Chem B. 2015 Jun 18;119(24):7407-16. doi: 10.1021/jp511021v. Epub 2015 Jan 30.
Understanding charge separation and charge transport is crucial for improving the efficiency of organic solar cells. Their active media are based on organic molecules and polymers, serving as both light-absorbing and transport layers. The charge-transfer (CT) states play an important role, being intermediate for free carrier generation and charge recombination. Here, we use light-induced electron paramagnetic resonance spectroscopy to study the CT dynamics in blends of the polymers P3HT, PCDTBT, and PTB7 with the fullerene derivative C60-PCBM. Time-resolved EPR measurements show strong spin-polarization patterns for all polymer-fullerene blends, confirming predominant generation of singlet CT states and partial orientation ordering near the donor-acceptor interface. These observations allow a comparison with charge separation processes in molecular donor-acceptor systems and in natural and artificial photosynthetic assemblies, and thus the elucidation of the initial steps of sequential CT in organic photovoltaic materials.
理解电荷分离和电荷传输对于提高有机太阳能电池的效率至关重要。它们的活性介质基于有机分子和聚合物，兼具光吸收层和传输层的功能。电荷转移（CT）态起着重要作用，是自由载流子产生和电荷复合的中间过程。在此，我们使用光诱导电子顺磁共振光谱来研究聚合物P3HT、PCDTBT和PTB7与富勒烯衍生物C60-PCBM混合物中的CT动力学。时间分辨EPR测量显示，所有聚合物-富勒烯混合物都有很强的自旋极化模式，证实了单线态CT态的主要产生以及施主-受主界面附近的部分取向有序化。这些观察结果有助于与分子施主-受主系统以及天然和人工光合组件中的电荷分离过程进行比较，从而阐明有机光伏材料中连续CT的初始步骤。
