Solution processed WO3 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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127 Citations (Scopus)


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 (sWO3) 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 sWO3 layer is incorporated in the organic photovoltaic devices (OPVs) with a structure of ITO/sWO3/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 sWO3 is significantly enhanced due to the air- and photo-stability of the sWO3 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 sWO3 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
Issue number6
Publication statusPublished - 2012 Jun

Bibliographical note

Funding Information:
This research was supported by New and Renewable Energy Program through the Korea Institute of Energy Technology Evaluation and Planning (KETEP) funded by the Ministry of Knowledge Economy (MKE) ( 008NPV08J010000 ), the Pioneer Research Center Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology ( 2009-0081500 ) and Industry Resource Technology Development Program (Contract: 10034648) from Korea Ministry of Knowledge and Economy.


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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • General Chemistry
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering


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