Pentacene mobility

There have been many reports of elevated mobilities in pentacene TFTs. Table 2.2 summarizes some of these results, some of which have been discussed in the text. New reports appear frequently, continuing to push the limits for high-mobility pentacene devices. 

D. Gundlach, Y. Lin, T. Jackson, S. Nelson, D. Schlom, IEEE Electr. Dev. Lett., 1997, 18, 87. [The term fhin-film phase, was not used in this publication, but was adopted later to refer to the 15 A d-spadng observed in some, often higher mobility pentacene layers.]... 

Nelson, S. F., Lin, Y.Y., Gundlach, D.J., and Jackson, T.N., Temperature-independent transport in high-mobility pentacene transistors, Appl. Phys. Lett, 72, 1854, 1998. 

Angelis, F.D. et al.. High field-effect mobility pentacene thin-film transistors with polymethylmethacrylate buffer layer, Appl. Phys. Lett. 86, 203505, 2005. 

T. T. M. (2004) Effect of impurities on the mobility of single crystal pentacene. Appl. Phys. Lett., 84, 3061-3063. 

Klauk H, Halik M, Zschieschang U, Schmid G, Radlik W, Weber W (2002) High-mobility polymer gate dielectric pentacene thin film transistors. J Appl Phys 92(9) 5259-5263... 

Fig. 17 Temperature dependence of the hole mobility measured in an FET with (a) pentacene and (b) P3HT as active layers. Parameter Is the gate voltage. Data fitting using the Fishchuk et al. theory in [102] yields values for the mobility and the disorder potential extrapolated to zero electric field and zero carrier concentration. To is the Meyer-Nedel temperature (see text). From [102] with permission. Copyright (2010) by the American Institute of Physics...

In an attempt to combine band-Uke charge carrier motion realized in an -inevitably fragile - crystalline FET structure with structural robustness and flexibility, Sakanoue and Sirringhaus [167] prepared FETs using spin coated films of 6,13-bis(triisopropylsilylethynyl)(TIPS)-pentacene films in contact with a perfluorinated, low dielectric-constant polymer gate electrode. The (linear) hole mobility at room temperature is 0.8 cm /V s with tendency of an apparent band-like negative temperature coefficient of the mobility (d/i/dT < 0). 

Minari T, Nemoto T, Isoda S (2006) Temperature and electric-field dependence of the mobility of a single-grain pentacene field-effect transistor. J Appl Phys 99 034506... 

Ruiz R, Papadimitratos A, Mayer AC, Maliiaras GG (2005) Thickness dependence of mobility in pentacene thin film transistors. Adv Mater 17 1795-1798... 

Both synthesis and properties of functionalized pentacene and anthra-dithiophene 447 were reported (05JA4986 06MI3708). Anthradithiophenes functionalized on the thiophene ring were reported to yield good hole mobility from vapor-deposited films (on order of 0.1 cm2 V [ s [). Acenedithiophenes with absorption at 653 nm have been reported (04OL3325). Tetrathiophene anthracene derivatives have been described showing absorption at 431 nm and emission at 437 nm (07OL4187). 

Pentacene is the material most used for preparation of p-type OTFTs based on small molecules, with oligothiophenes and their derivatives being the nest most important. The highest reported mobility is up to 6 cm2 V-1 s-1 for the former [76] and 1 cm2 V-1 s-1 for the latter [77]. 

Optimization of pentacene TFTs for mobility has led to some very promising results, but implementation of pentacene circuits in product applications has been limited, because of poor understanding and limited data on operational and shelf life stability in different circuit architectures. A notable exception to this is the implementation of Philips pentacene active-matrix backplanes in Polymer Vision s... 

This chapter will give an overview of methods used to achieve higher mobilities in pentacene devices, will point out potential progress in understanding the nature of exceptional mobility in these devices, and will comment on possible routes to stabilize device performance. 

There is a very short list of organic semiconductors with reported thin-film field-effect mobilities greater than 1 cm2 V-1 s h These include pentacene, sexithio-phene [5a], and anthradithiophene [17]. If we extend this list to include single crystal and n-type materials, we can add perylene [18], rubrene [19], copper phtha-locyanine (CuPc) [20], tetracyanoquinodimethane (TCNQ) [21], and dithiophene-tetrathiofulvalene (DT-TTF) [22] - still a short list. 

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