Reducing exciton-polaron annihilation in organic planar heterojunction solar cells

Bregt Verreet, Ajay Bhoolokam, Alyssa Brigeman, Rijul Dhanker, David Cheyns, Paul Heremans, Andre Stesmans, Noel C. Giebink, Barry P. Rand

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We investigate the relationship between charge concentration, exciton concentration, and photocurrent generation in fullerene-containing heterojunction diodes. Impedance measurements on C60 diodes reveal a charge buildup at the C60/bathocuproine (BCP) interface that can be swept out under reverse bias. In solar cell structures, a similar charge buildup is observed in dark conditions, and increases as a function of incident light intensity. Photoluminescence measurements reveal that the C60 exciton concentration is voltage dependent, explained via the process of exciton-polaron annihilation. This process has a negative impact on the generated photocurrent of the solar cells and thereby decreases the fill factor. A combination of electroabsorption, photoluminescence, and impedance measurements reveal a decrease in charge buildup and the associated exciton-polaron annihilation through the use of a BCP/3,4,9,10-perylenetetracarboxylic bis-benzimidazole/Ag cathode.

Original languageEnglish (US)
Article number115304
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number11
StatePublished - Sep 4 2014

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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