Zhang Guichuan, Chen Xian-Kai, Xiao Jingyang, Chow Philip C Y, Ren Minrun, Kupgan Grit, Jiao Xuechen, Chan Christopher C S, Du Xiaoyan, Xia Ruoxi, Chen Ziming, Yuan Jun, Zhang Yunqiang, Zhang Shoufeng, Liu Yidan, Zou Yingping, Yan He, Wong Kam Sing, Coropceanu Veaceslav, Li Ning, Brabec Christoph J, Bredas Jean-Luc, Yip Hin-Lap, Cao Yong
State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, 510640, Guangzhou, P. R. China.
Innovation Center of Printed Photovoltaics, South China Institute of Collaborative Innovation, 523808, Dongguan, P.R. China.
Nat Commun. 2020 Aug 7;11(1):3943. doi: 10.1038/s41467-020-17867-1.
A major challenge for organic solar cell (OSC) research is how to minimize the tradeoff between voltage loss and charge generation. In early 2019, we reported a non-fullerene acceptor (named Y6) that can simultaneously achieve high external quantum efficiency and low voltage loss for OSC. Here, we use a combination of experimental and theoretical modeling to reveal the structure-property-performance relationships of this state-of-the-art OSC system. We find that the distinctive π-π molecular packing of Y6 not only exists in molecular single crystals but also in thin films. Importantly, such molecular packing leads to (i) the formation of delocalized and emissive excitons that enable small non-radiative voltage loss, and (ii) delocalization of electron wavefunctions at donor/acceptor interfaces that significantly reduces the Coulomb attraction between interfacial electron-hole pairs. These properties are critical in enabling highly efficient charge generation in OSC systems with negligible donor-acceptor energy offset.
有机太阳能电池（OSC）研究面临的一个主要挑战是如何尽量减少电压损失与电荷产生之间的权衡。2019年初，我们报道了一种非富勒烯受体（名为Y6），它可以同时实现有机太阳能电池的高外部量子效率和低电压损失。在这里，我们结合实验和理论建模来揭示这种最先进的有机太阳能电池系统的结构-性质-性能关系。我们发现，Y6独特的π-π分子堆积不仅存在于分子单晶中，也存在于薄膜中。重要的是，这种分子堆积导致：（i）形成离域且发光的激子，从而实现较小的非辐射电压损失；（ii）供体/受体界面处电子波函数的离域，显著降低界面电子-空穴对之间的库仑吸引力。这些特性对于在供体-受体能量偏移可忽略不计的有机太阳能电池系统中实现高效电荷产生至关重要。
