Effect of PTB7 Properties on the Performance of PTB7: PC71BM Solar Cells

Chap Hang To, Annie Ng, Qi Dong, Aleksandra B. Djurišić, Juan Antonio Zapien, Wai Kin Chan, Charles Surya

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


(Graph Presented) The effect of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexy)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) properties on the optical properties, charge transport and photovoltaic performance of PTB7:[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) blend films is investigated. We found that the variations in the molecular weight (Mw) and polydispersity index (PDI) of PTB7 mainly affect the phase separation and charge transport (hole mobility) in the blend films. The optical properties are also affected, but the increase in the extinction coefficient does not necessarily imply increased power conversion efficiency. The obtained power conversion efficiency for optimized thickness varied from 4.8% to 7.8% depending on the properties of PTB7. The wide range of obtained power conversion efficiencies illustrates the importance of optimizing the Mw and PDI to optimize bulk heterojunction morphology and achieve high performance solar cells.

Original languageEnglish
Pages (from-to)13198-13207
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number24
Publication statusPublished - Jun 24 2015
Externally publishedYes


  • polymer solar cells
  • spectroscopic ellipsometry

ASJC Scopus subject areas

  • Materials Science(all)

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