OFET Device Fabrication

As expected, n-type OFET devices fabricated from single crystals display higher performance than those made from thin solid films because of the more... 

Fig. 1. Chemical structures of 1 and 2 and OFET device fabrication steps (a) vapor deposition of 1 or 2, (b) exposure of film 1 or 2 to Cl6Si20 vapors to complete the v-SAND structure, (c) vapor deposition of pentacene, and (d) vapor deposition of Au electrodes through a shadow mask.

Stille coupling has been used by Li et al to synthesize the donor-acceptor co-polymer P23 consisting of dithienyl-DPP and fused thienothiophene (TT) units. OFET devices fabricated from this polymer showed a high hole mobility of 0.94 cm V s due to significant intermolecular %-% donor-acceptor interactions between TT and DPP fused heterocyclic units.Additionally, a stannyl derivative of dithienothiophene has been recently co-polymerized by Shahid et al. with bis(5-bromo-2-thiophenyl)- and bis(5-bromo-2-selenophe-nyl)-DPP comonomers. Both polymers exhibited ambipolar characteristics in OFET devices. The thiophene-based co-polymer analog showed a higher... 

The device scheme of the OFET employed is shown in the inset of Fig. 1 (a). Details of device fabrication of the C60 OFETs are reported previously [1,5]. The deposition of the C60 was done at RT using a Leybold Univex system at base pressure of 10 6 mbar. The completed devices were loaded in the Oxford cryostat under N atmosphere inside the glove box to avoid exposure to ambient conditions. 

CPB Materials. Various types of silane crosslinkers were employed to fabricate crosslinked polymer blend (CPB) dielectrics in this study (Fig. 4). The reactivity of each crosslinker was tested via in situ NMR kinetic studies. The CPB dielectrics were fabricated on various substrates using mixture of polymer and crosslinker solution via spin-coating and gravure-printing. Organic semiconductors and source/ drain electrodes were vacuum-deposited to complete the OFET device. Dielectric and OFET properties were measured under vacuum and ambient as described previously. 

Organic field effect transistor (OFET) devices have been fabricated from pBTTT polymer solutions and hole mobility values of up to 0.8cm /V s were reported in a nitrogen atmosphere. These values approach that of high performing evaporated small molecule devices and are comparable to amorphous silicon. In bottom gate, bottom-contact devices, in which the active semiconductor layer is the exposed top surface, the effect of different ambient conditions has been evaluated. Exposure to unpurified, ambient air in which the humidity is -50%, results in an initial increase in the off-current of the device. In filtered, low humidity air, transistor devices remain very stable over time. 

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