A Difluoro-Methoxylated Ending-Group Asymmetric Small Molecule Acceptor Lead Efficient Binary Organic Photovoltaic Blend

Weiwei Wu; Bosen Zou; Ruijie Ma; Jia Yao; Chunliang Li; Zhenghui Luo; Bomin Xie; Memoona Qammar; Top Archie Dela Peña; Mingjie Li; Jiaying Wu; Chuluo Yang; Qunping Fan; Wei Ma; Gang Li; He Yan

doi:10.1002/smll.202402793

A Difluoro-Methoxylated Ending-Group Asymmetric Small Molecule Acceptor Lead Efficient Binary Organic Photovoltaic Blend

Small. 2024 May 16:e2402793. doi: 10.1002/smll.202402793. Online ahead of print.

Authors

Weiwei Wu¹, Bosen Zou¹, Ruijie Ma², Jia Yao¹, Chunliang Li¹, Zhenghui Luo³, Bomin Xie⁴, Memoona Qammar⁵, Top Archie Dela Peña^{1

6

7}, Mingjie Li⁶, Jiaying Wu⁷, Chuluo Yang³, Qunping Fan⁴, Wei Ma⁴, Gang Li², He Yan¹

Affiliations

¹ Department of Chemistry Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, 999077, P. R. China.
² Department of Electrical and Electronic Engineering, Research Institute for Smart Energy (RISE), Photonic Research Institute (PRI), The Hong Kong Polytechnic University, Hong Kong, 999077, P. R. China.
³ Guangdong Provincial Key Laboratory of New Energy Materials Service Safety, Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, P. R. China.
⁴ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
⁵ Department of Chemistry, The Hong Kong University of Science and Technology (HKUST), Clear Water Bay Rd, Kowloon, Hong Kong, 999077, P. R. China.
⁶ Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, 999077, P. R. China.
⁷ Function Hub, Advanced Materials Thrust, The Hong Kong University of Science and Technology, Nansha, Guangzhou, 511400, P. R. China.

PMID: 38757420
DOI: 10.1002/smll.202402793

Abstract

Developing a new end group for synthesizing asymmetric small molecule acceptors (SMAs) is crucial for achieving high-performance organic photovoltaics (OPVs). Herein, an asymmetric small molecule acceptor, BTP-BO-4FO, featuring a new difluoro-methoxylated end-group is reported. Compared to its symmetric counterpart L8-BO, BTP-BO-4FO exhibits an upshifted energy level, larger dipole moment, and more sequential crystallinity. By adopting two representative and widely available solvent additives (1-chloronaphthalene (CN) and 1,8-diiodooctane (DIO)), the device based on PM6:BTP-BO-4FO (CN) photovoltaic blend demonstrates a power conversion efficiency (PCE) of 18.62% with an excellent open-circuit voltage (V_OC) of 0.933 V, which surpasses the optimal result of L8-BO. The PCE of 18.62% realizes the best efficiencies for binary OPVs based on SMAs with asymmetric end groups. A series of investigations reveal that optimized PM6:BTP-BO-4FO film demonstrates similar molecular packing motif and fibrillar phase distribution as PM6:L8-BO (DIO) does, resulting in comparable recombination dynamics, thus, similar fill factor. Besides, it is found PM6:BTP-BO-4FO possesses more efficient charge generation, which yields better V_OC-J_SC balance. This study provides a new ending group that enables a cutting-edge efficiency in asymmetric SMA-based OPVs, enriching the material library and shed light on further design ideas.

Keywords: asymmetric acceptor; difluoro‐methoxylated end‐group; organic photovoltaic; power conversion efficiency.

Abstract

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