Influences of surface roughness of ZnO electron transport layer on the photovoltaic performance of organic inverted solar cells

Zaifei Ma, Zheng Tang, Ergang Wang, Mats R. Andersson, Olle Inganas, Fengling Zhang

    Research output: Contribution to journalArticle

    92 Citations (Scopus)

    Abstract

    Here, we demonstrate the correlation between the surface roughness of the ZnO interlayer used as an electron transporting interlayer (ETL) in organic inverted solar cells (ISCs) and the photovoltaic performance of the ISCs. Three different surfaces of the ZnO ETL are studied in ISCs with the polymer poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) mixed with [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as the active layer. The results obtained from these ISCs show that power conversion efficiency increases from 2.7% to 3.9% when the root-mean-square roughness of the ZnO layer decreases from 48 to 1.9 nm. Moreover, it is found that the short-circuit current density is higher in the ISC based on the smoother ZnO interlayer, with a larger donor/acceptor (D/A) interfacial area in the active layer that facilitates exciton dissociation. The reduced effective interfacial area between the photoactive layer and the ZnO interlayer with decreased ZnO surface roughness leads to an observed improvement in both fill factor and open-circuit voltage, which is ascribed to a reduced concentration of traps at the interface between the ZnO interlayer and the active layer.

    Original languageEnglish
    Pages (from-to)24462-24468
    Number of pages7
    JournalJournal of Physical Chemistry C
    Volume116
    Issue number46
    DOIs
    Publication statusPublished - 2012

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