“Double-Cable” Conjugated Polymers with Linear Backbone toward High Quantum Efficiencies in Single-Component Polymer Solar Cells

• Published in: Journal of the American Chemical Society 2017-12, Vol.139 (51), p.18647-18656
• Main Authors: Feng, Guitao, Li, Junyu, Colberts, Fallon J. M, Li, Mengmeng, Zhang, Jianqi, Yang, Fan, Jin, Yingzhi, Zhang, Fengling, Janssen, René A. J, Li, Cheng, Li, Weiwei
• Format: Article
• Language: English
• Subjects: crystal structure; crystallization; dissociation; electron transfer; energy; fluorine; polymers; solar cells; sulfur
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.7b10499

A series of “double-cable” conjugated polymers were developed for application in efficient single-component polymer solar cells, in which high quantum efficiencies could be achieved due to the optimized nanophase separation between donor and acceptor parts. The new double-cable polymers contain electron-donating poly­(benzo­dithiophene) (BDT) as linear conjugated backbone for hole transport and pendant electron-deficient perylene bisimide (PBI) units for electron transport, connected via a dodecyl linker. Sulfur and fluorine substituents were introduced to tune the energy levels and crystallinity of the conjugated polymers. The double-cable polymers adopt a “face-on” orientation in which the conjugated BDT backbone and the pendant PBI units have a preferential π–π stacking direction perpendicular to the substrate, favorable for interchain charge transport normal to the plane. The linear conjugated backbone acts as a scaffold for the crystallization of the PBI groups, to provide a double-cable nanophase separation of donor and acceptor phases. The optimized nanophase separation enables efficient exciton dissociation as well as charge transport as evidenced from the highup to 80%internal quantum efficiency for photon-to-electron conversion. In single-component organic solar cells, the double-cable polymers provide power conversion efficiency up to 4.18%. This is one of the highest performances in single-component organic solar cells. The nanophase-separated design can likely be used to achieve high-performance single-component organic solar cells.