Bridging donor-acceptor energy offset using organic dopants as energy ladders to improve open-circuit voltages in bulk-heterojunction solar cells

Jan Kai Chang, Ya Ching Kuo, Yu Jen Chen, An Lun Lo, I. Hsiu Liu, Wei Hsuan Tseng, Kaung-Hsiung Wu, Mei Hsin Chen*, Chih I. Wu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

A systematic way to improve the open circuit voltage of bulk-heterojunction (BHJ) organic photovoltaics is demonstrated by incorporating energy ladder material to form a ternary blend with cascade energy structures. We propose that doping organic molecules with appropriate energetic alignment to bridge the donor-acceptor energy offset can facilitate exciton dissociation and hence improve open-circuit voltage (Voc) and power conversion efficiency. The cascade energy alignment structure is measured via ultraviolet photoemission spectroscopy. The Voc and power conversion efficiency of devices using the proposed schemes can be enhanced by 10% and 20%, respectively. The results provide a new path toward higher power conversion efficiency in BHJ systems by engineering the energy structures of the materials in the active layers.

Original languageEnglish
Pages (from-to)3458-3464
Number of pages7
JournalOrganic Electronics
Volume15
Issue number12
DOIs
StatePublished - 1 Jan 2014

Keywords

  • Open-circuit voltage
  • Organic photovoltaics
  • Ternary cascade energy alignment

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