Random Polymerization Strategy Leads to a Family of Donor Polymers Enabling Well‐Controlled Morphology and Multiple Cases of High‐Performance Organic Solar Cells. Issue 52 (13th November 2020)

• Record Type: Journal Article
• Authors: Liang, Jiaen; Pan, Mingao; Chai, Gaoda; Peng, Zhengxing; Zhang, Jianquan; Luo, Siwei; Han, Qi; Chen, Yuzhong; Shang, Ao; Bai, Fujin; Xu, Yuan; Yu, Han; Lai, Joshua Yuk Lin; Chen, Qing; Zhang, Maojie; Ade, Harald; Yan, He
• Is Part Of: Advanced materials. Volume 32:Issue 52(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-13
• Subjects: donor polymers -- nonfullerene organic solar cells -- random polymerization strategy; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202003500
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Developing high‐performance donor polymers is important for nonfullerene organic solar cells (NF‐OSCs), as state‐of‐the‐art nonfullerene acceptors can only perform well if they are coupled with a matching donor with suitable energy levels. However, there are very limited choices of donor polymers for NF‐OSCs, and the most commonly used ones are polymers named PM6 and PM7, which suffer from several problems. First, the performance of these polymers (particularly PM7) relies on precise control of their molecular weights. Also, their optimal morphology is extremely sensitive to any structural modification. In this work, a family of donor polymers is developed based on a random polymerization strategy. These polymers can achieve well‐controlled morphology and high‐performance with a variety of chemical structures and molecular weights. The polymer donors are D–A1–D–A2‐type random copolymers in which the D and A1 units are monomers originating from PM6 or PM7, while the A2 unit comprises an electron‐deficient core flanked by two thiophene rings with branched alkyl chains. Consequently, multiple cases of highly efficient NF‐OSCs are achieved with efficiencies between 16.0% and 17.1%. As the electron‐deficient cores can be changed to many other structural units, the strategy can easily expand the choices of high‐performance donor polymers for NF‐OSCs. Abstract : To fine‐tune the energy levels of polymer donors, a family of random polymers is synthesized, which shows favorable properties of aggregation and morphology. The performance of these polymers is less sensitive to their molecular weights compared with PM7. Thus, multiple cases of highly efficient nonfullerene organic solar cells are achieved with efficiencies between 16.0% and 17.1%.