Efficient polymer solar cells enabled by alkoxy-phenyl side-chain-modified main-chain-twisted small molecular acceptors. Issue 42 (23rd October 2020)

• Record Type: Journal Article
• Authors: Zhao, Baofeng; Wang, Weiping; Xie, Yuan; Zhao, Heng; Wang, Liuchang; Liu, Sha; Xin, Jingming; Cong, Zhiyuan; Wu, Haimei; Liang, Quanbin; Ma, Wei; Gao, Chao; Wu, Hongbin; Cao, Yong
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 42(2020)
• Page Start: 22335
• Page End: 22345
• Publication Date: 2020-10-23
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0ta07960j
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : Alkoxy-phenyl-modified twisted NFAs with optimized film morphology achieve enhanced performances in polymer solar cells. Abstract : Four new main-chain-twisted acceptor–donor–acceptor-type (A–D–A) non-fullerene acceptors (i-mO-4F, i-mO-4Cl, i-pO-4F, and i-pO-4Cl ) were designed and synthesized, featuring the introduction of meta -hexyloxy-phenyl and para -hexyloxy-phenyl side-chains in the fused-ring core as well as 2-(5, 6-difluoro-3-oxo-2, 3-dihydro-1 H -inden-1-ylidene)malononitrile and 2-(5, 6-dichlorine-3-oxo-2, 3-dihydro-1 H -inden-1-ylidene)malononitrile as the end-capping groups. All four small molecules exhibited broad absorption spectra in the range of 300 nm to 820 nm with a corresponding small optical bandgap of 1.55 eV (i-mO-4F ), 1.53 eV (i-mO-4Cl ), 1.52 eV (i-pO-4F ), and 1.48 eV (i-pO-4Cl ), which ensured total complementary absorption with a wide bandgap polymer donor material (PBDB-T ). Although i-mO-4Cl possessed a finely bathochromic-shifted absorption spectrum, its poor morphology with PBDB-T in the blend films led to a low power conversion efficiency (PCE) of 7.41%. In contrast, the optimal PBDB-T :i-mO-4F -, PBDB-T :i-pO-4F -, and PBDB-T :i-pO-4Cl -based devices achieved promising PCEs of 14.02%, 13.47%, and 10.98%, respectively. The obtained significantly different results for these two types of NFAs, on the one hand, demonstrate the synergistic effect of the hexyloxy-phenyl side-chain modification and non-planar main-chain strategy to construct highly efficient non-fullerene acceptors for polymer solar cells, and on the other hand, reveal the influence of the fluorinated and chlorinated end-groups on the morphologies and performances of the resultant main-chain-twisted NFAs.