Non-fullerene based organic solar cells show excellent optoelectronic properties. In this study, firstly, we measured the magneto-photocurrent (MPC) effect to monitor the spin orbit coupling (SOC) action of electron-hole pairs at the donor: acceptor (D:A) interfaces, introduced by the dipole-dipole interaction in non-fullerene ITIC molecules. The MPC of non-fullerene based bulk heterojunctions show a broader line-shape, which implies a stronger SOC in electron-hole pairs at D:A interface as compared to the fullerene based bulk heterojunctions under photo-excitation. Secondly, the light-induced electron paramagnetic resonance (LEPR) results further give a direct evidence for stronger SOC in electron-hole pairs at D:A interface in non-fullerene bulk-heterojunction. Theoretically, increasing SOC provides a pathway for singlet electron-hole pairs to convert into triplet electron-hole pairs, leading to more spin states ready for dissociation. Therefore, the increased SOC will increase the magneto-photocurrent, and improve the performance of non-fullerene solar cells, we consider that photoexcitation can present a new approach to strengthen the SOC effect in organic solar cells toward better photovoltaic actions.

基于非富勒烯的有机太阳能电池显示出优异的光电性能。在这项研究中，首先，我们测量了磁光电流 (MPC) 效应，以监测由偶极-偶极相互作用引入的供体：受体 (D:A) 界面处电子-空穴对的自旋轨道耦合 (SOC) 作用在非富勒烯 ITIC 分子中。基于非富勒烯的本体异质结的 MPC 显示出更宽的线形，这意味着与光激发下的基于富勒烯的本体异质结相比，D:A 界面处的电子-空穴对中更强的 SOC。其次，光诱导电子顺磁共振（LEPR）结果进一步直接证明了非富勒烯体异质结中 D:A 界面处的电子-空穴对中的 SOC 更强。理论上，增加 SOC 为单线态电子-空穴对转换为三线态电子-空穴对提供了途径，从而导致更多的自旋态准备解离。因此，增加的 SOC 将增加磁光电流，并提高非富勒烯太阳能电池的性能，我们认为光激发可以提供一种新的方法来加强有机太阳能电池中的 SOC 效应，以实现更好的光伏作用。