Double-Cable Conjugated Polymers with Rigid Phenyl Linkers for Single-Component Organic Solar Cells
Shijie Liang, Jing Wang, Yanni Ouyang, Wen Liang Tan, Christopher R. McNeill, Qiaomei Chen, Zheng Tang, Weiwei Li
Abstract
Nonradiative recombination loss is the key factor to be responsible for low open-circuit voltage (Voc) in organic solar cells (OSCs), which can be reduced via tuning the chemical structure of conjugated materials. However, the intrinsic correlation between them was rarely studied. In this work, we were able to build a strong connection between chemical structure and nonradiative recombination loss, which was then used to lower the voltage losses in OSCs. The studies start from designing several double-cable conjugated polymers with rigid phenyl linkers, which guarantee the precise distance between donor (D) backbone and acceptor (A) side units. In addition, the number of phenyl linkers was changed from one to three, so as to provide different D/A distances. The universal studies of solar cells, morphology, and voltage losses showed that longer D/A distance provided lower nonradiative recombination losses and hence higher Voc in single-component OSCs. Our results demonstrate that extending the D/A distance via rigid phenyl linkers is an efficient way to reduce the voltage losses in OSCs.