National Synchrotron Light Source Lunch Time Seminar

Various organic thin film transistors (OTFTs) containing conjugated materials are now becoming commercially available in the form of light emitting diodes, and proto-type electronic polymer circuits of pi-pi conjugated polymers or oligomers. Successful uses of these devices are presently being demonstrated. Thin films for OTFT applications can be fabricated through various film processing techniques, such as vacuum deposition and solution casting. Since the performance of OTFT devices is inherently related to the local ordered structure of these semiconducting films, it is important to achieve a greater control of the self-assembly of semiconducting materials on functionalized dieletric substrates. Specifically, the desire to make nanometer scale devices for future electronic applications further emphasizes a preferential orientation of pi-pi conjugated crystal planes, as a hole-transporting path in p- or n-type semiconductor-based OTFTs. Herein, I introduce the effects of crystalline structures in pentacene, oligothiophene derivative, PTCDI-C13, TES-ADT, TIPS pentacene, F8T2, PQT12, and poly (3-alkyl thiophene) thin films, as organic semiconductors, on their charge-transport behaviors in OTFTs using two-dimensional grazing-incidence X-ray diffraction and atomic force microscopy (AFM). Interconnection between crystal grains, as a prerequisite for high performance OTFT applications, is highlighted via conducting-AFM characterization.