Pentacene carrier mobilities

Mottaghi and Horowitz [164] have investigated the degradation of carrier mobility in pentacene TFTs due to effect of electric field. They fabricated pentacene-based OTFTs with bottom-gate, top-contact architecture. Alumina was used as substrate. In one set of devices pentacene was deposited directly on alumina. In the second set of devices a fatty... 

Growth Morphologies and Charge Carrier Mobilities of Pentacene Organic Field Effect Transistors with RF Spnttered Alumininm Oxide Gate Insnlators on ITO Glass... 

Growth Morphologies and Charge Carrier Mobilities of Pentacene Organic... 

Comparing the situation for PTCDA with the above discussed cases of pery-lene and pentacene which exhibit a large diffusion already at room temperature (due to their smaller sublimation enthalpy) thus indicates that the film structure of large molecules such as PTCDA prepared at room temperature may not represent the thermodynamic equilibrium structure. Finally, we note that PTCDA reveals only a rather small charge carrier mobility (for thin films values of less than 3 X 10 cmW s were reported [67]), and thus is not well suited for the fabrication of OFETs. 

As a result of the above, and of the direct competition between molecule-substrate and intermolecular interactions, the presence of the metal or insulator can induce interface polymorphs which do not exist in the bulk. Examples for this are the specific thin film phases of pentacene on insulators [16, 74, 75] or metals (e.g., Cu(llO) [16]), the a- and 3-phases of tetraeene on Ag(l 11) [69], or the square phases of PTCDA on Ag(l 11) [30] and Au(l 11) [84]. It is evident that the charge carrier mobilities of organic semiconductors will depend on the crystal phase. 

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