Effect of a large hole reservoir on the charge transport in TiO2/organic hybrid devices

Simon Sandén, Oskar Sandberg, Xu Qian, Jan-Henrik Smått, Gytis Juška, Mika Lindén, Ronald Österbacka

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    We have fabricated hybrid devices in the form of indium tin oxide/titanium dioxide/poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester/copper (ITO/TiO(2)/P3HT:PCBM/Cu) to clarify the impact of the TiO(2)/P3HT:PCBM interface on the charge transport using the charge extraction by linearly increasing voltage (CELIV) technique. We found that a large equilibrium charge reservoir is accumulated at negative offsets at the TiO(2)/P3HT:PCBM interface leading to space charge limited extraction current (SCLC) transients. We show analytically the SCLC transient response and compare the experimental data to calculated SCLC at a linearly increasing voltage. The theoretical calculations indicate that the large charge reservoir at negative offset voltages is due to thermally generated charges combined with poor hole extraction at the ITO/TiO(2) contact, due to the hole blocking character of TiO(2).
    Original languageUndefined/Unknown
    Pages (from-to)14186–9
    JournalPhysical Chemistry Chemical Physics
    Issue number41
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed

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