Wu Lirong, Xie Lingchao, Tian Hanmin, Peng Ruixiang, Huang Jiaming, Fanady Billy, Song Wei, Tan Songting, Bi Wengang, Ge Ziyi
School of Electronics and Information Engineering, Tianjin Key Laboratory of Electronic Materials and Devices, Hebei University of Technology, Tianjin 300401, China.
Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China; Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, China.
Sci Bull (Beijing). 2019 Aug 15;64(15):1087-1094. doi: 10.1016/j.scib.2019.06.008. Epub 2019 Jun 8.
A novel small-molecule (SM) acceptor DTF-IC is designed and synthesized in this work. The power conversion efficiency (PCE) of ternary OSCs increased up to 12.14% from 10.90% by incorporating 10 wt% of DTF-IC as second acceptors into the binary OSCs consisting of PBDB-T as donor and IT-M as acceptor. This was mainly due to the large increase in short-circuit current (J) from 16.18 to 17.95 mA/cm, without any drop in the open-circuit voltage (V) and fill factor (FF). The addition of DTF-IC enabled the donor and acceptor to form a distinct complementary absorption profile in the visible-light region, which boosted the photon harvesting in the range of 730-800 nm and consequently increased the J of the ternary system by 11%. Moreover, there was an energy transfer between the two SM acceptors, favorable for enhancing charge separation and transfer as well as reducing charge recombination at PBDB-T:IT-M and PBDB-T:DTF-IC interface. Simultaneously, HOMO and LUMO energy levels of DTF-IC were lower than those of PBDB-T, but still higher than those of IT-M. Thus, DTF-IC is able to provide a cascading energy level with the host donor and acceptor which are beneficial for efficient charge transfer between the acceptors and facilitating exciton dissociation and carrier transport. Meanwhile, the highly crystalline DTF-IC as a third component can improve the crystallization process of the active layer while maintaining proper phase separation. This work proposes a novel idea for non-fullerene acceptors achieved via twin spiro-type structure modifying by indanone and provides a new direction for the selection of ternary solar cell materials.
在本工作中设计并合成了一种新型小分子（SM）受体DTF-IC。通过将10 wt%的DTF-IC作为第二受体引入由PBDB-T作为供体和IT-M作为受体组成的二元有机太阳能电池（OSC）中，三元OSC的功率转换效率（PCE）从10.90%提高到了12.14%。这主要是由于短路电流（J）从16.18大幅增加到17.95 mA/cm²，而开路电压（V）和填充因子（FF）均未下降。DTF-IC的加入使供体和受体在可见光区域形成了明显的互补吸收光谱，这增强了730 - 800 nm范围内的光子捕获，从而使三元体系的J增加了11%。此外，两种SM受体之间存在能量转移，有利于增强电荷分离和转移，并减少PBDB-T:IT-M和PBDB-T:DTF-IC界面处的电荷复合。同时，DTF-IC的最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能级低于PBDB-T，但仍高于IT-M。因此，DTF-IC能够与主体供体和受体提供级联能级，这有利于受体之间的高效电荷转移，并促进激子解离和载流子传输。同时，高度结晶的DTF-IC作为第三组分可以改善活性层的结晶过程，同时保持适当的相分离。本工作为通过茚满酮修饰的双螺环型结构实现非富勒烯受体提出了新思路，并为三元太阳能电池材料的选择提供了新方向。
