Bromination: An Alternative Strategy for Non‐Fullerene Small Molecule Acceptors. Issue 9 (28th February 2020)

• Record Type: Journal Article
• Authors: Wang, Huan; Liu, Tao; Zhou, Jiadong; Mo, Daize; Han, Liang; Lai, Hanjian; Chen, Hui; Zheng, Nan; Zhu, Yulin; Xie, Zengqi; He, Feng
• Is Part Of: Advanced science. Volume 7:Issue 9(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-02-28
• Subjects: bromination -- intermolecular interactions -- non‐fullerene acceptors -- open‐circuit voltage -- polymer solar cells; Science -- Periodicals; 505
• DOI: 10.1002/advs.201903784
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: The concept of bromination for organic solar cells has received little attention. However, the electron withdrawing ability and noncovalent interactions of bromine are similar to those of fluorine and chlorine atoms. A tetra‐brominated non‐fullerene acceptor, designated as BTIC‐4Br, has been recently developed by introducing bromine atoms onto the end‐capping group of 2‐(3‐oxo‐2, 3‐dihydro‐1H‐inden‐1‐ylidene) malononitrile and displayed a high power conversion efficiency (PCE) of 12%. To further improve its photovoltaic performance, the acceptor is optimized either by introducing a longer alkyl chain to the core or by modulating the numbers of bromine substituents. After changing each end‐group to a single bromine, the BTIC‐2Br‐ m ‐based devices exhibit an outstanding PCE of 16.11% with an elevated open‐circuit voltage of V oc = 0.88 V, one of the highest PCEs reported among brominated non‐fullerene acceptors. This significant improvement can be attributed to the higher light harvesting efficiency, optimized morphology, and higher exciton quenching efficiencies of the di‐brominated acceptor. These results demonstrate that the substitution of bromine onto the terminal group of non‐fullerene acceptors results in high‐efficiency organic semiconductors, and promotes the use of the halogen‐substituted strategy for polymer solar cell applications. Abstract : The bromination of non‐fullerene acceptors provides a promising alternative approach for the creation of high‐performance organic solar cells. BTIC‐2Br‐ m ‐based devices exhibit an outstanding power conversion efficiency of 16.11% with an elevated open circuit voltage of 0.88 V, representing one of the highest efficiencies in brominated non‐fullerene acceptors.