Charge transfer excitons in low band gap polymer based solar cells and the role of processing additives

Markus C. Scharber*, Christoph Lungenschmied, Hans-Joachim Egelhaaf, Gebhard Matt, Mateusz Bednorz, Thomas Fromherz, Jia Gao, Dorota Jarzab, Maria A. Loi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

60 Citations (Scopus)
444 Downloads (Pure)

Abstract

Organic semiconductor blends yielding efficient charge generation and transport are key components for the development of high performance organic bulk-heterojunction solar cells. In this paper the effect of the processing additive octane-dithiol on the charge transfer emission in poly[2,6-(4,4-bis-(2-ethylhexyl)- 4H-cyclopenta[2,1-b; 3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) is investigated. Despite the fact that blends processed with and without additive show a ground state charge transfer optical absorption only the blend processed without additive shows a corresponding charge transfer emission. The presented experimental data show that the nano-morphology of the bulk-heterojunction blends plays an important role for the formation of emissive charge transfer excitons, and that it is a loss channel in the studied solar cells.

Original languageEnglish
Pages (from-to)5077-5083
Number of pages7
JournalEnergy & Environmental Science
Volume4
Issue number12
DOIs
Publication statusPublished - Dec-2011

Keywords

  • OPEN-CIRCUIT VOLTAGE
  • BULK HETEROJUNCTIONS
  • CONJUGATED POLYMER
  • ALKANE DITHIOLS
  • TRANSFER STATES
  • EFFICIENCY
  • RECOMBINATION
  • PERFORMANCE
  • MORPHOLOGY
  • BLENDS

Cite this