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HL: Fachverband Halbleiterphysik

HL 38: Organic electronics and photovoltaics II (DS, jointly with CPP, HL, O)

HL 38.12: Vortrag

Dienstag, 12. März 2013, 12:30–12:45, H32

n-channel percolation in a pentacene-C60 ambipolar organic thin film transistor — Simon Noever, Stefan Fischer, and •Bert Nickel — Ludwig-Maximilians-Universität, Fakultät für Physik & CENS, München, D

We present [1] a well balanced ambipolar organic field effect transistor with high hole and electron saturation mobilities of 0.28 cm*/Vs and 0.18 cm*/Vs, respectively. The structure and morphology of the respective films are analyzed using AFM and GIXS methods. Furthermore, we track the formation of a pentacene-C60 heterojunction by in-situ measurements during deposition of C60. Upon percolation of the n-channel, the heterojunction charges, acting as an additional top gate for the hole conducting channel. The fact that the p-channel threshold does not shift before the n-channel develops highlights two interesting findings for bilayer ambipolar TFTs. Apparently, before the C60 film percolates, the fullerene islands are electronically floating and the charging of the interface is confined to the pentacene-C60 contact area. Secondly, the threshold voltage shift of the p-channel upon fullerene percolation implicates the generation of a second hole conducting channel at the pentacene top surface. The introduced method demonstrates a way to evaluate the electrostatic situation in operating organic heterojunction devices. [1] S. Noever, S. Fischer, B. Nickel, Advanced Materials (in press)