Synthesis of a new ladder-type benzodi(cyclopentadithiophene) arene with forced planarization leading to an enhanced efficiency of organic photovoltaics

Yung Lung Chen, Chih Yu Chang, Yen-Ju Cheng*, Chain-Shu Hsu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

90 Scopus citations

Abstract

We have developed a new heptacyclic benzodi(cyclopentadithiophene) (BDCPDT) unit, where 3,7-positions of the central benzo[1,2-b:4,5-b′]dithiophenes (BDT) subunit are covalently rigidified with 3-positons of the two external thiophenes by two carbon bridges, forming two external CPDT rings that share two thiophene rings with the central BDT core. The distannyl-BDCPDT building block was copolymerized with 1,3-dibromo-thieno[3,4-c]pyrrole-4,6-dione (TPD) by Stille polymerization to afford a new alternating donor-acceptor copolymer PBDCPDT-TPD. The implementation of forced planarization greatly suppresses the interannular twisting to extend the effective conjugated length and preserve the interactions between the donor and acceptor segments. The device using the PBDCPDT-TPD/PC 71BM (1:3 in wt%) blend processed with dimethyl sulfoxide as an additive delivered a marked PCE of 6.6% which represents a significant enhancement compared to the device using the corresponding nonfused polymer analogue with a PCE of 0.2%.

Original languageEnglish
Pages (from-to)3964-3971
Number of pages8
JournalChemistry of Materials
Volume24
Issue number20
DOIs
StatePublished - 23 Oct 2012

Keywords

  • additive
  • conjugated polymers
  • forced planarization
  • solar cells

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