A study on the importance of isolation of the active regions for high performance organic circuits

ABSTRACTThe authors present electrical comparisons on an array of test structures including organic lateral diodes and thin film transistors (OTFT), fabricated with a range of disordered and polycrystalline organic semiconductors, to examine the increasing need for effective isolation for organic-based circuits. As the minimum feature size decreases, circuit components become closely positioned, which leads to increased electrical crosstalk. The organic semiconductors utilised for this work include solution-processable organic semiconductors such as disordered polymers P3HT and PTAA, and a polycrystalline material TIPS-pentacene. In order to predict the magnitude required for isolation for the different semiconductors, simple test structures have been designed consisting of two gold electrodes separated by a distance ranging from 4 μm up to 2000 μm. The bulk conductivity from such test structures provides the limits at which circuit components may be placed for crosstalk free operation. The work presented culminates in the development of an isolation layer to help reduce the off-currents and gate leakages of the OTFTs.