Enhancement of photovoltaic properties in supramolecular polymer networks featuring a solar cell main-chain polymer H-bonded with conjugated cross-linkers

Dhananjaya Patra, Mohan Ramesh, Duryodhan Sahu, Harihara Padhy, Chih Wei Chu, Kung-Hwa Wei, Hong-Cheu Lin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

Stille polymerization was employed to synthesize a low-band-gap (LBG) conjugated main-chain polymer PBTH consisting of bithiazole, dithieno[3,2-b:2′,3′-d]pyrroles (DTP), and pendent melamine derivatives. Novel supramolecular polymer networks PBTH/C and PBTH/F were developed by mixing proper molar amounts of polymer PBTH (containing melamine pendants) to be hydrogen-bonded (H-bonded) with complementary uracil-based conjugated cross-linkers C and F (i.e., containing two symmetrical uracil moieties connected with carbazole and fluorene units through triple bonds). The formation of multiple H-bonds between polymer PBTH and cross-linkers C or F was confirmed by FT-IR measurements. In contrast to polymer PBTH, the supramolecular design with multiple H-bonds can enhance the photovoltaic properties of polymer solar cell (PSC) devices containing H-bonded polymer networks PBTH/C and PBTH/F by tuning their light harvesting capabilities, HOMO energy levels, and crystallinities. Initially, the power conversion efficiency (PCE) values of PSC devices containing supramolecular polymer networks PBTH/C and PBTH/F as electron donors and [6,6]-phenyl-C71-butyric acid methyl ester (PC 70BM) as an electron acceptor (polymer:PC70BM = 1:1 w/w) are found to be 0.97 and 0.68%, respectively, in contrast to 0.52% for polymer PBTH. The highest PCE value of 1.56% with a short-circuit current densities (Jsc) value of 7.16 mA/cm2, a open circuit voltages (Voc) value of 0.60 V, and a fill factor (FF) of 0.36 was further optimized in the PSC device containing a supramolecular polymer network PBTH/C as polymer:PC70BM = 1:2 w/w. These results indicate that supramolecular design is an effective route towards better photovoltaic properties of Voc, Jsc, and PCE values in polymer solar cells.

Original languageEnglish
Pages (from-to)1219-1228
Number of pages10
JournalPolymer
Volume53
Issue number6
DOIs
StatePublished - 9 Mar 2012

Keywords

  • H-bonded cross-linker
  • Polymer network
  • Supramolecule

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