Photobleaching Dynamics in Small Molecule vs. Polymer Organic Photovoltaic Blends with 1,7-Bis-Trifluoromethylfullerene

Wade Braunecker, Steven Christensen, Andrew Ferguson, Nikos Kopidakis, Bryon Larson, Zbyslaw Owczarczyk, Jason Pfeilsticker, Vinila Viswanathan, Colin Brook, Praveen Ramamurthy, Steven Strauss, Olga Boltalina, Logan Garner, Dylan Arias

Research output: Contribution to journalArticlepeer-review

16 Scopus Citations

Abstract

Two organic photovoltaic (OPV) donor materials (one polymer and one small molecule) are synthesized from the same constituent building blocks, namely thiophene units, cyclopentathiophene dione (CTD), and cyclopentadithiophene (CPDT). Photobleaching dynamics of these donor materials are then studied under white light illumination in air with blends of PC70BM and the bis-trifluoromethylfullerene 1,7-C60(CF3)2. For both the polymer and small molecule blends, C60(CF3)2 stabilizes the initial rate of photobleaching by a factor of 15 relative to PC70BM. However, once the small molecule:C60(CF3)2 blend bleaches to ∼80% of its initial optical density, the rate of photobleaching dramatically accelerates, which is not observed in the analogous polymer blend. We probe that phenomenon using time-resolved photoluminescence (TRPL) to measure PL quenching efficiencies at defined intervals during the photobleaching experiments. The data indicates the small molecule donor and C60(CF3)2 acceptor significantly de-mix with time, after which the blend begins to bleach at approximately the same rate as the neat donor sample. The work suggests that perfluoroalkylfullerenes have great potential to stabilize certain OPV active layers toward photodegradation, provided their morphology is stable.

Original languageAmerican English
Pages (from-to)4623-4628
Number of pages6
JournalJournal of Materials Chemistry A
Volume6
Issue number11
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5900-70695

Keywords

  • donor materials
  • OPV
  • organic photovoltaics

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