Title: Enhancement of photovoltaic properties in supramolecular polymer networks featuring a solar cell main-chain polymer H-bonded with conjugated cross-linkers
Authors: Patra, Dhananjaya
Ramesh, Mohan
Sahu, Duryodhan
Padhy, Harihara
Chu, Chih-Wei
Wei, Kung-Hwa
Lin, Hong-Cheu
Department of Materials Science and Engineering
Department of Photonics
Keywords: H-bonded cross-linker;Supramolecule;Polymer network
Issue Date: 9-Mar-2012
Abstract: Stille polymerization was employed to synthesize a low-band-gap (LOG) 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-C-71-butyric acid methyl ester (PC70BM) 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 (J(sc)) value of 7.16 mA/cm(2), a open circuit voltages (V-oc) 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 V-oc, J(sc), and PCE values in polymer solar cells. (C) 2012 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.polymer.2012.01.026
ISSN: 0032-3861
DOI: 10.1016/j.polymer.2012.01.026
Journal: POLYMER
Volume: 53
Issue: 6
Begin Page: 1219
End Page: 1228
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