Electronic and chemical properties of ZnO in inverted organic photovoltaic devices

Anirudh Sharma, Joseph Franklin, Birendra Singh, Gunther Andersson, David Lewis

    Research output: Contribution to journalArticle

    22 Citations (Scopus)

    Abstract

    Photo-conversion efficiency of inverted polymer solar cells incorporating pulsed laser deposited ZnO electron transport layer have been found to significantly increase from 0.8% to up to 3.3% as the film thickness increased from 4 nm to 100 nm. While the ZnO film thickness was found to have little influence on the morphology of the resultant ZnO films, the band structure of ZnO was found to evolve only for films of thickness 25 nm or more and this was accompanied by a significant reduction of 0.4 eV in the workfunction. The films became more oxygen deficient with increased thickness, as found from X-ray photoelectron spectroscopy (XPS) and valence band XPS (VBXPS). We attribute the strong dependence of device performance to the zinc to oxygen stoichiometry within the ZnO layers, leading to improvement in the band structure of ZnO with increased thickness.

    Original languageEnglish
    Pages (from-to)131-136
    Number of pages6
    JournalORGANIC ELECTRONICS
    Volume24
    DOIs
    Publication statusPublished - 3 Jun 2015

    Keywords

    • Band structure of ZnO
    • Inverted OPVs
    • Pulsed laser deposited ZnO
    • Workfunction
    • XPS and UPS

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