Diffusion length and langevin recombination of singlet and triplet excitons in organic heterojunction solar cells

David Ompong, Jai Singh

    Research output: Contribution to journalArticle

    Abstract

    We derived new expressions for the diffusion length of singlet and triplet excitons by using the Föster and Dexter transfer mechanisms, respectively, and have found that the diffusion lengths of singlet and triplet excitons are comparable. By using the Langevin recombination theory, we derived the rate of recombination of dissociated free charges into their excitonic states. We found that in some organic polymers the probabilities of recombination of free charge carriers back into the singlet and triplet states are approximately 65.6 and 34.4 %, respectively, indicating that Langevin-type recombination into triplet excitons in organic semiconductors is less likely. This implies that the creation of triplet excitons may be advantageous in organic solar cells, because this may lead to dissociated free charge carriers that can be collected at their respective electrodes, which should result in better conversion efficiency.
    Original languageEnglish
    Pages (from-to)1281-1285
    Number of pages5
    JournalChemPhysChem
    Volume16
    Issue number6
    DOIs
    Publication statusPublished - 27 Apr 2015

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