Asymmetrical side-chain engineering of small-molecule acceptors enable high-performance nonfullerene organic solar cells

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

2 Scopus Citations
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Author(s)

  • Bin Kan
  • Xuebin Chen
  • Ke Gao
  • Ming Zhang
  • Francis Lin
  • Xiaobin Peng
  • Feng Liu

Related Research Unit(s)

Detail(s)

Original languageEnglish
Article number104209
Journal / PublicationNano Energy
Volume67
Online published24 Oct 2019
Publication statusPublished - Jan 2020

Abstract

Three new small molecules based on the benzo [1,2-b:4,5-b’]dithiophene (BDT) fused central core with different side-chains, namely DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl, are designed and synthesized to investigate the side-chain effect on the properties of nonfullerene acceptors. DPBDT-4Cl has symmetrical phenylalkyl side-chains on the central BDT unit. In order to narrow the bandgap and reduce the steric hindrance, the phenylalkyl chains are systematically replaced with the flexible electron-donating alkoxy side-chain (POBDT-4Cl) and alkyl side-chain (COBDT-4Cl). As a result, POBDT-4Cl and COBDT-4Cl are characterized with asymmetry-featured side-chains. From DPBDT-4Cl to POBDT-4Cl to COBDT-4Cl, their light absorption abilities, molecular packing behaviors and crystallinity are gradually enhanced. The devices based on these three acceptors all show power conversion efficiencies (PCEs) over 11% with energy loss below 0.55 eV. Compared to DPBDT-4Cl, POBDT-4Cl and COBDT-4Cl obviously exhibit enhanced device performance with improved short-circuit current densities (Jsc) and fill factors (FFs), which mainly ascribe to their reduced charge recombination and enhanced charge transport. In addition, the COBDT-4Cl achieved a high efficiency of 13.5% with a Jsc of 21.8 mA cm−2 and an FF of 0.71. This result is among the best performance obtained from asymmetry-featured small molecules.

Research Area(s)

  • Asymmetrical, Benzo[1,2-b:4,5-b’]dithiophene, Side-chains, Small-molecule acceptors

Citation Format(s)

Asymmetrical side-chain engineering of small-molecule acceptors enable high-performance nonfullerene organic solar cells. / Kan, Bin; Chen, Xuebin; Gao, Ke; Zhang, Ming; Lin, Francis; Peng, Xiaobin; Liu, Feng; Jen, Alex K-Y.

In: Nano Energy, Vol. 67, 104209, 01.2020.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal