Since bulk conductivity in organic crystals was discovered in the 1960s, high mobilities for single-crystal organic semiconductors have been reported with 35 cm2 V−1s−1 for pentacene. Similarly high mobilities have been measured for other aromatic organic semiconductors. However, these large aromatic molecules are generally insoluble for solution-processing. Optimized films have been prepared by solution-processing derivatized molecules, such as TIPS-pentacene. However, optimized devices using modified pentacene can reach a carrier mobility of only 6 cm2 V−1s−1. Pure pentacene can be deposited by vacuum sublimation, but it requires complicated and expensive equipment. Recently, we have demonstrated that pentacene and C60 can be directly solution processed in a standard chemistry laboratory without complicated equipment. We are working at improving the method to produce thin films for organic field-effect transistors. We are developing methods for doctor-blading these thin films, e.g., precise chemical etching into a substrate, where we can then deposit our pentacene solution to make a thin film with controlled thickness in the pattern on the etched substrate. This enables patterned deposition of a controlled thickness of organic semiconductors that is compatible with standard semiconductor processes. We will discuss our progress on this method.

Benchtop deposition of patterned thin films of pentacene

253rd National Meeting (2017)

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