Unfused Acceptors Matching π‐Bridge Blocks with Proper Frameworks Enable Over 12% As‐Cast Organic Solar Cells. Issue 25 (23rd May 2022)

• Record Type: Journal Article
• Authors: Liu, Yue; Lin, Zhijie; Cao, Jinru; Du, Fuqiang; Wang, Hongtao; He, Shi; Tang, Weihua
• Is Part Of: Small. Volume 18:Issue 25(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-23
• Subjects: π‐bridge block -- as‐cast organic solar cells -- molecular frameworks -- unfused acceptors; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202201209
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Emerging unfused‐ring acceptors (UFAs) have been explored in pursuit of low‐cost high‐efficient organic solar cells (OSCs). Assembling unfused building blocks into proper frameworks are challenging for the molecular design of UFAs. The authors report herein four UFAs adopting either dithiophene cyclopentadiene (DTC) or dithieno[3, 2‐ b :2', 3'‐ d ]pyrrole (DTP) as π‐bridge units with different molecular frameworks for high‐efficient as‐cast OSCs. All these acceptors exhibit strong near‐infrared absorption and narrow optical band gap ( E g opt < 1.50 eV). DTC‐bridged symmetric and DTP‐bridged asymmetric UFAs exhibit higher planar conformation as well as suitable miscibility and homogeneous phase separation when blending with polymer donor PBDB‐T to promote efficient charge transport in the blends. Their blends with PBDB‐T contribute optimal PCE of 12.17% and 11.92% in as‐cast OSCs, among the highest values for UFAs based as‐cast devices in the literature. Experimental and theoretical simulations systematically reveal the impact of manipulating the molecular framework of UFAs on their conformation, optoelectronic, and photovoltaic performance. The results indicate the matching π‐bridge units with molecular frameworks as an attractive approach to design UFAs for high‐performance as‐cast OSCs. Abstract : Unfused acceptors are designed by employing dithieno[3, 2‐b:2', 3'‐d]pyrrole and dithiophene cyclopentadiene as π‐bridge blocks to construct different frameworks. The best‐performing as‐cast OSCs readily contribute an optimal efficiency of 12.17% and 11.92%, among the highest values reported for the unfused acceptors‐based devices so far.