Effect of annealing on exciton diffusion in a high performance small molecule organic photovoltaic material

Yun Long, Gordon James Hedley, Arvydas Ruseckas, Mithun Chowdhury, Thomas Jean Roland, Luis Serrano, Graeme Cooke, Ifor David William Samuel

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21 Citations (Scopus)
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Abstract

Singlet exciton diffusion was studied in the efficient organic photovoltaic electron donor material DTS(FBTTh2)2. Three complementary time-resolved fluorescence measurements were performed: quenching in planar heterojunctions with an electron acceptor; exciton-exciton annihilation; and fluorescence depolarization. The average exciton diffusivity increases upon annealing from 1.6 × 10-3 cm2 s-1 to 3.6 × 10-3 cm2 s-1, resulting in an enhancement of the mean two–dimensional exciton diffusion length (LD=√4Dτ) from 15 nm to 27 nm. About 30% of the excitons get trapped very quickly in as-cast films. The high exciton diffusion coefficient of the material leads to it being able to harvest excitons efficiently from large donor domains in bulk heterojunctions.
Original languageEnglish
Pages (from-to)14945-14952
JournalACS Applied Materials & Interfaces
Volume9
Issue number17
Early online date30 Mar 2017
DOIs
Publication statusPublished - 3 May 2017

Keywords

  • Organic solar cells
  • Organic semiconductors
  • Light harvesting
  • Excitation energy transfer
  • Bulk heterojunctions

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