Effect of molecular weight of gate dielectric (Polyvinylalcohol) and solvents on operational stability of organic field effect transistors

The effects ofmolecularweight and the solvents used for gate dielectric deposition on output and transfer characteristics ofOFETdeviceswith bottomgate contact have been studied. Polyvinylalcohol (PVA)withmolecularweights 30000 and 145000 g/ mol (PVA1 and PVA2, respectively)was used as gate dielectric and deionized-water and dimethylsulfoxide (DMSO) as solvents.This studydemonstratedthat both themolecularweight and solvent affect the output and transfer characteristics of theOFETdevices.Consider-ableimprovement inthresholdvoltagehasbeenachieved for eachmolecularweight in the case ofDMSOused as solvent. The observed clockwise hysteresis fromthe Vgs-Ids curves and their solvent dependence implies that the presence of the polar groups inside the gate dielectric can control device characteristics.