Thin-film transistor transport

Dinelli F, Murgia M, Levy P, Cavallini M, Biscarini F, de Leeuw DM (2004) Spatially correlated charge transport in organic thin film transistors. Phys Rev Lett 92 116802-116803... 

R. J. Chesterfield, J. C. McKeen, C. R. Newman, P. C. Ewbank, D. Filho, J.-L. Bredas, L. L. Miller, K. Mann, and C. D. Frisbie, Organic thin film transistors based on N-alkyl perylene diimides Charge transport kinetics as a function of gate voltage and temperature , Journal of Physical Chemistry B 108, 19281 (2004). 

Pentacene is attracting considerable attention as its charge transport properties are excellent [4, 48], and films of pentacene on silicon oxide are commonly used for thin film transistors in which the silicon oxide serves as gate dielectric. 

This is of particular interest since for all pentacene-based thin film transistors using high work function electrodes (such as gold) only p-type transport has been found although pentacene is intrinsically an ambipolar semiconductor. Note, that previously n-type transport has only been observed in connection with low work function electrodes such as calcium [80] (see also Chapter 24 by Benson et al.). In accord with previous findings by Friend and coworkers [78] we propose that we can observe n-conduction in our model device because the presence of any OH-groups at the SAM/pentacene interface can be safely excluded by the use of ultra-clean electrodes. 

Unlike thin film transistors, electroluminescence devices operate in a high electric field, and therefore homogeneity and low defect density of the thin films are more important than the carrier transport characteristics. In this sense, the approach to the use of nematic semiconductors by Kelly and O Neill should be reasonable. 

For application to thin film transistors (TFTs), which can operate electronic papers, high carrier mobility exceeding 0.01 cm2 V-1 s-1 is necessary. For this purpose, nematic semiconductors with low molecular order, resulting in relatively low carrier mobility, are not suitable. For application of thin films of semiconductors to TFTs, stabilization of the highly ordered smectic phases, which exhibit high carrier mobility, by photopolymerization may be desirable. Kreouzis et al. studied the carrier transport properties of photopolymer-izable phenylnaphthalene, diphenylbithiophene, and quaterthiophene derivatives having an oxetane moiety or l,4-pentadien-3-yloxy in their alkyl side chain (Fig. 21) [107,108],... 

Babel, A., Wind, J.D. and Jenekhe, S.A., Ambipolar charge transport in air-stable polymer blend thin-film transistors, Adv. Func. Mater, 14, 891-898, 2004. 

Bouchoms, I.P.M., Schoonveld, W.A., Vrijmoeth J., and Klapwijk, T.M., Morphology identification of the thin film phases of vacuum evaporated pentacene on Si02, Synth. Met. 104, 175, 1999 Knipp, D., Street, R.A., Volkel, A., and Ho, J., Pentacene thin film transistors on inorganic dielectrics Morphology, stmctural properties, and electronic transport, J. Appl. Phys. 93, 347, 2003. 

Knipp, D. et al., Pentacene thin film transistors on inorganic dielectrics Morphology, structural properties, and electronic transport, J. Appl. Phys. 93, 347-355, 2003. 

These few examples of ability to probe transport on local length scales by CP-AFM show a broadly applicable approach to quantifying the effects of microstructure and contacts on the performance of organic thin film transistors. 

Horowitz, G. and Hajlaoui, M.E., Charge transport in polycrystalline ohgothiophene thin film transistors, Synt. Met. 121, 1349-1350, 2001. 

Franco Dinelli, Mauro Murgia, Pablo Levy, Massimiliano Cavallini, Fabio Bis-carini, and Dago M. de Leeuw. Spatially Correlated Charge Transport in Organic Thin Film Transistors. Physical Review Letters, 92(11) 116802, 2004. 

---