Acid-functionalized fullerenes used as interfacial layer materials in inverted polymer solar cells

Hyosung Choi, Junghoon Lee, Wonho Lee, Seo Jin Ko, Renqiang Yang, Jeong Chul Lee, Han Young Woo, Changduk Yang, Jin Young Kim

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Two types of carboxylic acid functionalized fullerence derivatives, 4-(2-ethylhexyloxy)-[6,6]-phenyl C61-butyric acid (p-EHO-PCBA) and bis-4-(2-ethylhexyloxy)-[6,6]-phenyl C61-butyric acid (bis-p-EHO-PCBA), were synthesized and investigated as an interfacial layer for inverted polymer solar cells (iPSCs). The -COOH groups on the PCBAs chemisorb to inorganic metal oxide (TiOX), generating fullerene-based self-assembled monolayers (FSAMs). The devices with the mono- and bis-FSAMs exhibited substantially lower series resistance (RS) values of 2.10 Ω cm2 and 1.46 Ω cm2, compared to that (4.15 Ω cm2) of the unmodified device. The TiOX films modified with mono- and bis-FSAMs showed higher contact angles of 50 and 91, respectively, than that of the pristine TiOX film (33). The increased contact angles were attributed to the enhanced hydrophobicity, improving the wetting properties with the organic photoactive layer. In addition, a comparison of device characteristics with electroactive FSAMs and non-electroactive benzoic acid SAMs clearly indicates that the FSAMs may suggest an additional pathway for photo-induced charge transfer and charge collection to ITO. After surface modification with FSAMs, the short-circuit current density (J SC) and fill factor (FF) values increased substantially. The iPSCs based on poly(5,6-bis(octyloxy)-4-(thiophen-2-l)benzo[c][1,2,5]thiadiazole) (PTBT) and [6,6]phenyl-C61-butyric acid methyl ester (PCBM) as an active layer showed remarkably improved power conversion efficiency up to 5.13% through incorporation of the FSAMs-based interfacial layer.

Original languageEnglish
Pages (from-to)3138-3145
Number of pages8
JournalOrganic Electronics: physics, materials, applications
Volume14
Issue number11
DOIs
Publication statusPublished - 2013 Aug 19
Externally publishedYes

Keywords

  • Fullerene
  • Interfacial layer
  • Inverted polymer solar cells
  • Self-assembled monolayer
  • Surface modification

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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