OFETs field-effect mobility

Figure 14-13. Evolution of the field-effect mobility of OFETs for five organic materials polythio-phenc (PT) and its derivatives, qualerthiophcne (4T), scxithio-phenc (6T), dihcxyl-sexithiophene (DH6T). and pcntaecnc.

Using naphthalenetetracarboxylic dianhydride as the semiconductor, changes in bulk conductivity, field-effect mobility, and threshold voltage were separately observed in response to exposure to water and oxygen [35, 36], Another more elaborate kind of pattern was produced by a virtual array of eleven different semiconductor OFET monitoring on-current in response to polar and nonpolar organic vapors [37]. Responses (0.8-0.3-fold reductions and 1.5-2-fold increases) were dis-... 

M = Tb, Lu) into organic thin-film transistors by LB technique and reported their field effect mobility, which represented the first report for p-type OFETs based on bis(phthalocyaninato) rare earth complexes prepared via LB method [88], Due to the highly ordered molecular arrangement of M(Pc)[Pc(OC8Hi7)g] (M = Tb, Lu) in LB films and the appropriate HOMO energy level of these double-deckers relative to the Au source-drain electrodes, the OFETs reported in that work exhibited higher hole transfer mobility of 1.7 x 10-3 cm2 V-1 s-1 in comparison with those fabricated from monomeric phthalocyanine LB films. 

The performance of OFETs has continuously improved since they were first reported in 1987 [8, 9]. The rate of the progress can be visualized in Figure 14-13, where we have plotted the field-effect mobility of five prominent organic com-pounds as a lunclion of the publication date. The data include one polymer, polythiophene and its derivatives and four small molecules (three oligothiophenes, plus pentacene). Note that the highest mobility of small molecules was reported on single crystals. 

Empolying such a Ca passivated Si02 insulator in combination with Ca drain-source electrodes, n-t5q3c pentacene OFETs can be realised as has been demonstrated by Ahles et al. [29]. This, however, holds only for thin Ca layers as will be shown in the following, where the influence of the Ca passivation thickness on the electron transport in pentacene OFETs is discussed. Illustrated in Figiue 24.8 is the electron field effect mobility in dependence of the Ca thickness. By eonsidering the mobility of pristine devices, which have not... 

Using DHPT-SC as the semiconductor in OFETs, a field effect mobility of 0.012 cmWs and a current on/off ratio of >10 can be realised, which is among the highest OFET mobilities fabricated achieved with solution-processed oligothiophenes. 

For OFETs made from BT5, we obtained a field-effect mobility of... 

Figure 6.12 Field-effect mobilities and current on/off ratios of OFET devices annealed at 120 °C for different time intervals, using DHBTP-SC (circles) and DHPT-SC (rectangles) as the semiconductors. Open symbols depict the on/off current ratio whereas solid symbols the field-effect mobility.

FIGURE 2.1.23 Pressure dependence of the field-effect mobility (a) and the threshold voltage (b) in single-crystal rubrene OFETs (solid and open symbols correspond to the increasing and decreasing pressure). (From Rang, Z. et ah, Appl. Phys. Lett., 86, 123501, 2005.)... 

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