Molecular-Shape-Controlled Nonfused Ring Electron Acceptors for High-Performance Organic Solar Cells with Tunable Phase Morphology
Xiaodong Wang, Hao Lu, Andong Zhang, Na Yu, Guangliu Ran, Zhaozhao Bi, Xiaodi Yu, Xinjun Xu, Yahui Liu, Zheng Tang, Wenkai Zhang, Wei Ma, Zhishan Bo
Abstract
Two nonfused ring electron acceptors (NFREAs), BTh-OC8-2F and DTh-OC8-2F, with different molecular shapes are designed and synthesized. Both acceptors can form planar molecular shapes by the assistance of S···O intramolecular interactions. Differently, BTh-OC8-2F, with a linear molecular backbone and two trans-arranged side chains at the core unit, exhibits much stronger crystallinity than DTh-OC8-2, with a C-shape molecular shape and two cis-arranged steric side chains at the core unit. Thus, the DTh-OC8-2F based blend film displays a better nanoscale phase separation, more suppressed charge recombination, more efficient exciton dissociation, and lower nonradiative energy loss. Organic solar cells based on DTh-OC8-2F can deliver a power conversion efficiency of 14.13%, which is much higher than BTh-OC8-2F based ones (11.95%) and is also one of the highest values reported for organic solar cells based on NFREAs.