Self-assembled all-conjugated block copolymer as an effective hole conductor for solid-state dye-sensitized solar cells

Wei Chih Chen, Yi Huan Lee, Chia Yuan Chen, Kuo Chang Kau, Lu Yin Lin, Chi An Dai, Chun Guey Wu, Kuo Chuan Ho, Juen Kai Wang, Leeyih Wang

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

An all-conjugated diblock copolymer, poly(2,5-dihexyloxy-p-phenylene)-b- poly(3-hexylthiophene) (PPP-b-P3HT), was synthesized and applied as a hole transport material (HTM) for the fabrication of solid-state dye-sensitized solar cells (ss-DSCs). This copolymer is characterized by an enhanced crystallinity, enabling its P3HT component to self-organize into interpenetrated and long-range-ordered crystalline fibrils upon spin-drying and ultimately endowing itself to have a faster hole mobility than that of the parent P3HT homopolymer. Transient photovoltage measurements indicate that the photovoltaic cell based on PPP-b-P3HT as the HTM has a longer electron lifetime than that of the reference device based on P3HT homopolymer. Moreover, comparing the two ss-DSCs in terms of the electrochemical impedance spectra reveals that the electron density in the TiO2 conduction band is substantially higher in the PPP-b-P3HT device than in the P3HT cell. Above observations suggest that the PPP block facilitates an intimate contact between the copolymer and dye molecules absorbed on the nanoporous TiO2 layer, which significantly enhances the performance of the resulting device. Consequently, the PPP-b-P3HT ss-DSC exhibits a promising power conversion efficiency of 4.65%. This study demonstrates that conjugated block copolymers can function as superior HTMs of highly efficient ss-DSCs.

Original languageEnglish
Pages (from-to)1254-1262
Number of pages9
JournalACS Nano
Volume8
Issue number2
DOIs
StatePublished - 25 Feb 2014

Keywords

  • block copolymer
  • conjugated polymers
  • hole transport materials
  • self-assembly
  • solid-state dye-sensitized solar cells

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