Solution processed WO 3 layer for the replacement of PEDOT: PSS layer in organic photovoltaic cells

Hana Choi, Bongsoo Kim, Min Jae Ko, Doh Kwon Lee, Honggon Kim, Sung Hyun Kim, Kyungkon Kim

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101 Citations (Scopus)

Abstract

Tungsten oxide layer is formed uniformly by a sol-gel technique on top of indium tin oxide as a neutral and photo-stable hole extraction layer (HEL). The solution processed tungsten oxide layer (sWO 3) is fully characterized by UV-Vis, XPS, UPS, XRD, AFM, and TEM. Optical transmission of ITO/sWO 3 substrates is nearly identical to ITOs. In addition, the sWO 3 layer induces nearly ohmic contact to P3HT as PEDOT:PSS layer does, which is determined by UPS measurement. In case that an optimized thickness (∼10 nm) of the sWO 3 layer is incorporated in the organic photovoltaic devices (OPVs) with a structure of ITO/sWO 3/P3HT:PCBM/ Al, the power conversion efficiency (PCE) is 3.4%, comparable to that of devices utilizing PEDOT:PSS as HEL. Furthermore, the stability of OPV utilizing sWO 3 is significantly enhanced due to the air- and photo-stability of the sWO 3 layer itself. PCEs are decreased to 40% and 0% of initial values, when PEDOT:PSS layers are exposed to air and light for 192 h, respectively. In contrast, PCEs are maintained to 90% and 87% of initial PCEs respectively, when sWO 3 layers are exposed to the same conditions. Conclusively, we find that solution processed tungsten oxide layers can be prepared easily, act as an efficient hole extraction layer, and afford a much higher stability than PEDOT:PSS layers.

Original languageEnglish
Pages (from-to)959-968
Number of pages10
JournalOrganic Electronics: physics, materials, applications
Volume13
Issue number6
DOIs
Publication statusPublished - 2012 Jun 1

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Keywords

  • Device stability
  • Hole extraction layer
  • Metal oxide
  • Organic photovoltaic cells

ASJC Scopus subject areas

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

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