The effect of charge transfer state on the open-circuit voltage of small-molecular organic photovoltaic devices: A comparison between the planar and bulk heterojunctions using electroluminescence characterization

Chih Chien Lee, Wei Cheng Su, Wen Chang Chang, Bo Yao Huang, Shun Wei Liu

Research output: Contribution to journalArticle

13 Citations (Scopus)


This work studies the open-circuit voltage (VOC) of planar and bulk heterojunction organic photovoltaic (OPV) devices by means of electroluminescent (EL) technique to resolve the charge transfer (CT) states between donor and acceptor. The OPV devices containing a small part of bulk heterojunction increases the VOC as a result of the enhanced CT process as compared with a complete planar structure. Red shift of the CT charge transfer was observed by increasing the bulk volume, which indicates the increased degree of interaction between both molecules and excitons. By characterizing the EL spectra of OPV devices and relating them to the CT absorption, the interfacial property between the donor and acceptor is shown to be crucial for determining the VOC in small-molecule OPV devices. Detailed analysis of the energetic loss was also used to interpret the VOC under the effect of CT states.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalOrganic Electronics: physics, materials, applications
Publication statusPublished - Jan 1 2015
Externally publishedYes



  • Charge transfer state
  • Electroluminescence
  • Open-circuit voltage
  • Small-molecule organic photovoltaic device

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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