Critical Role of Polymer Aggregation and Miscibility in Nonfullerene‐Based Organic Photovoltaics
Abstract
Understanding the correlation between polymer aggregation, miscibility, and device performance is important to establish a set of chemistry design rules for donor polymers with nonfullerene acceptors (NFAs). Employing a donor polymer with strong temperature‐dependent aggregation, namely PffBT4T‐2OD [poly[(5,6‐difluoro‐2,1,3‐benzothiadiazol‐4,7‐diyl)‐alt‐(3,3″′‐di(2‐octyldodecyl)‐2,2′;5′,2″;5″,2″′‐quaterthiophen‐5,5‐diyl)], also known as PCE‐11 as a base polymer, five copolymer derivatives having a different thiophene linker composition are blended with the common NFA O‐IDTBR to investigate their photovoltaic performance. While the donor polymers have similar optoelectronic properties, it is found that the device power conversion efficiency changes drastically from 1.8% to 8.7% as a function of thiophene content in the donor polymer. Results of structural characterization show that polymer aggregation and miscibility with O‐IDTBR are a strong function of the chemical composition, leading to different donor–acceptor blend morphology. Polymers having a strong tendency to aggregate are found to undergo fast aggregation prior to liquid–liquid phase separation and have a higher miscibility with NFA. These properties result in smaller mixed donor–acceptor domains, stronger PL quenching, and more efficient exciton dissociation in the resulting cells. This work indicates the importance of both polymer aggregation and donor–acceptor interaction on the formation of bulk heterojunctions in polymer:NFA blends.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 29, 2020
- Source ID
- 10.1002/aenm.201902430
Entities
People
- Aram Amassian
- Bing Xu
- Carr Hoi Yi Ho
- Dovletgeldi Seyitliyev
- Evgeny O. Danilov
- Franky So
- Harald Ade
- John R. Reynolds
- Kenan Gundogdu
- Taesoo Kim
- Xueping Yi
- Zhengxing Peng
Organizations
- Georgia Tech
- National Science Foundation
- North Carolina State University
- Office of Basic Energy Sciences
- Office of Naval Research
- Office of Science
- United States Department of Energy