Photoreactive low-bandgap 4H-cyclopenta[2,1-b:3,4-b′]dithiophene and 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole-based alternating copolymer for polymer solar cell

U. Ra Lee, Tae Wan Lee, Mai Ha Hoang, Nam Su Kang, Jae Woong Yu, Kyung Hwan Kim, Kyung Geun Lim, Tae Woo Lee, Jung Il Jin, Dong Hoon Choi

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Polymer solar cells (PSCs) are often fabricated using a well-known 4H-cyclopenta[2,1-b:3,4-b′]dithiophene and 4,7-di(thiophen-2-yl)benzo[c] [1,2,5]thiadiazole-based polymer as a low-bandgap polymer. Further, PSCs are also fabricated by mixing methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) with the polymer. We prepared poly[4,4-bis(2- ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene-2,6-diyl-alt-4, 7-bis(2-thienyl)-2,1,3-benzothiadiazole-5′,5′′-diyl] after anchoring the penta-1,4-diene in the side chain of the cyclopentadithiophene and investigated the long-term performance stability of a photocrosslinked bulk heterojunction (BHJ) photovoltaic (PV) cell based on the polymer. The photocrosslinking reaction was monitored via infrared spectroscopy without the use of a photoinitiator, by carrying out a spontaneous radical coupling reaction. The polymer film has a broad absorption band extending from 300 to 850 nm with an optical bandgap as low as 1.52 eV. The polymer was employed to fabricate a PSC with PC61BM. The resultant PSC device, which was treated by UV irradiation (λ = 254 nm, I = 40 mW/cm2, 5 min), had good preliminary results with an open-circuit voltage of 0.62 V, a short-circuit current density of -5.37 mA/cm2, a fill factor of 0.41, and an overall power conversion efficiency of 1.37%. All parameters of the UV-cured PSC device were more stable over the course of 300 h than those of P3HT-PC61BM devices, indicating the long-term stability of the polymer.

Original languageEnglish
Pages (from-to)269-278
Number of pages10
JournalOrganic Electronics
Volume12
Issue number2
DOIs
Publication statusPublished - 2011 Feb

Keywords

  • Bulk heterojunction
  • Long-term stability
  • Low-bandgap polymer
  • Photoreaction
  • Polymer solar cell

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

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