Charge accumulation induced S-shape J-V curves in bilayer heterojunction organic solar cells

J. C. Wang, X. C. Ren, San-Qiang Shi, Chi Wah Leung, Paddy K.L. Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

144 Citations (Scopus)


We study the origin of the S-shape effect in the current-voltage curve of bilayer heterojunction organic solar cell induced by the exciton blocking layer (EBL). By gradually increasing the BCP thickness, the J-V curves change from exponential shape to S-shape, leading to a twofold degraded in the fill factor (FF). The variations of the J-V curves are attributed to the charge accumulation effect induced by the BCP layer. The charge accumulation phenomenon is further verified by the C-V measurements and a numerical model based on continuity and transport equations is developed to qualitatively reproduce the S-shape effect. Our finding provides insight into the origin of S-shape effect in bilayer heterojunction photovoltaic devices induced by the exciton blocking layer and reveals the importance of controlling charge accumulation for high performance OPVs especially the tandem devices.
Original languageEnglish
Pages (from-to)880-885
Number of pages6
JournalOrganic Electronics: physics, materials, applications
Issue number6
Publication statusPublished - 1 Jun 2011


  • Bilayer heterojunction
  • Charge accumulation
  • Organic solar cell
  • S-shape

ASJC Scopus subject areas

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


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