Photoactivation of an ionic p-type dopant used in a triarylamine based hole transporting material for enhancing conductivity of solution processed films

•Charge transfer from a triarylamine to the iodonium salt is confirmed.•Quantitative determination of the created free charge carrier concentration.•A photoactivation treatment is introduced, increasing doping efficiency 1000-fold.•The photoactivation is addressed on a molecular level. The ionic com...

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Veröffentlicht in:Synthetic metals 2017-08, Vol.230, p.105-112
Hauptverfasser: Seim, Henning, Haase, Nils, Scheible, Katja, Heil, Holger, Böhm, Edgar, Buchholz, Herwig, von Seggern, Heinz
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Sprache:eng
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Zusammenfassung:•Charge transfer from a triarylamine to the iodonium salt is confirmed.•Quantitative determination of the created free charge carrier concentration.•A photoactivation treatment is introduced, increasing doping efficiency 1000-fold.•The photoactivation is addressed on a molecular level. The ionic compound 4-isopropyl-4′-methyldiphenyliodonium tetrakis-(penta- fluorophenyl-borate) (DPI-TPFB) has been investigated as p-type dopant in a triarylamine (TAA) based hole transporting material (HTM). Charge transfer from the HTM to the iodonium salt has been verified and translates to an increase in conductivity of up to 5 orders of magnitude compared to non-doped HTM. UV photoactivation treatment of HTM:DPI-TPFB in solution was shown to increase conductivity by additional 2–3 orders of magnitude up to 2.6·10−2S/m. The concentration of free charge carriers and the related doping efficiency of DPI-TPFB was derived from current–voltage (I–V) measurements of hole only devices. It was possible to demonstrate that the activation treatment triggers a reaction on the molecular level of the iodonium salt. Possible causes for the increased doping efficiency of the system were explored using density functional theory calculations.
ISSN:0379-6779
1879-3290
DOI:10.1016/j.synthmet.2017.05.012