In this study, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) films were prepared by electrostatic spray deposition (ESD) for fabrication of bottom-contact organic field-effect transistors (OFETs) having the channel length of 5 µm. Since the crystalline quality of TIPS pentacene film strongly depends on the nature of the spray droplets, we investigated preparation condition of TIPS pentacene solution with mixed organic solvents. Large crystal domains were obtained by using a 1,2-diclorobenzene (o-DCB):ethanol mixed solvent. On the other hand, the film deposited using the toluene:ethanol mixed solvent was composed of small domains. Due to larger crystal domains obtained in the film deposited using the o-DCB:ethanol mixed solvent (i.e., reducing domain boundaries), we could fabricate the bottom-contact OFET exhibiting the field-effect mobility of 1.6×10-2 cm2/(V·s) which was almost 100 times higher than that based on the film deposited using the toluene:ethanol mixed solvent [2.0×10-4 cm2/(V·s)].

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This paper demonstrates that electrostatic spray deposition (ESD) method is a promising solution process to fabricate highly-crystalline organic films (6,13-bis(triisopropylsilylethynyl) pentacene; TIPS pentacene) for the use in bottom-contact organic field-effect transistors (OFETs). We obtained large crystalline domains (i.e., molecularly-oriented domains) by using an o-DCB:acetone mixed solvent (1:1), and observed good transistor behavior in an OFET having the channel length of 20 μm.