Impact of Nonfullerene Molecular Architecture on Charge Generation, Transport, and Morphology in PTB7-Th-Based Organic Solar Cells

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

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Author(s)

  • Xueping Yi
  • Bhoj Gautam
  • Iordania Constantinou
  • Zhengxing Peng
  • Erik Klump
  • Xiaochu Ba
  • Carr Hoi Yi Ho
  • Chen Dong
  • Seth R. Marder
  • John R. Reynolds
  • Harald Ade
  • Franky So

Detail(s)

Original languageEnglish
Article number1802702
Journal / PublicationAdvanced Functional Materials
Volume28
Issue number32
Online published21 Jun 2018
Publication statusPublished - 8 Aug 2018

Abstract

Despite the rapid development of nonfullerene acceptors (NFAs), the fundamental understanding on the relationship between NFA molecular architecture, morphology, and device performance is still lacking. Herein, poly[[4,8-bis[5-(2-ethylhexyl)thiophene-2-yl]benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]-thieno[3,4-b]thiophenediyl]] (PTB7-Th) is used as the donor polymer to compare an NFA with a 3D architecture (SF-PDI4) to a well-studied NFA with a linear acceptor–donor–acceptor (A–D–A) architecture (ITIC). The data suggest that the NFA ITIC with a linear molecular structure shows a better device performance due to an increase in short-circuit current ( Jsc) and fill factor (FF) compared to the 3D SF-PDI4. The charge generation dynamics measured by femtosecond transient absorption spectroscopy (TAS) reveals that the exciton dissociation process in the PTB7-Th:ITIC films is highly efficient. In addition, the PTB7-Th:ITIC blend shows a higher electron mobility and lower energetic disorder compared to the PTB7-Th:SF-PDI4 blend, leading to higher values of sc and FF. The compositional sensitive resonant soft X-ray scattering (R-SoXS) results indicate that ITIC molecules form more pure domains with reduced domain spacing, resulting in more efficient charge transport compared with the SF-PDI4 blend. It is proposed that both the molecular structure and the corresponding morphology of ITIC play a vital role for the good solar cell device performance.

Research Area(s)

  • charge generation, charge transport, molecular architecture, morphology, nonfullerene acceptors

Citation Format(s)

Impact of Nonfullerene Molecular Architecture on Charge Generation, Transport, and Morphology in PTB7-Th-Based Organic Solar Cells. / Yi, Xueping; Gautam, Bhoj; Constantinou, Iordania; Cheng, Yuanhang; Peng, Zhengxing; Klump, Erik; Ba, Xiaochu; Ho, Carr Hoi Yi; Dong, Chen; Marder, Seth R.; Reynolds, John R.; Tsang, Sai-Wing; Ade, Harald; So, Franky.

In: Advanced Functional Materials, Vol. 28, No. 32, 1802702, 08.08.2018.

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