Organic thin film devices with stabilized threshold voltage and mobility

The main claim of the patent is the use of ion implantation on organic semiconductors to modify and control their electrical, structural and chemical properties. By properly selecting the ion energy and dose, we are able to: a) effectively enhance the device lifetime by providing a surface protection effect for the organic active thin film against atmosphere and water vapors. (see details in the submitted manuscript) b) implant and chemically activate ions that can form bonds with the hydrocarbon matrix and locally modify the charge distribution within the organic thin film (see details in the submitted manuscript, relative to one species, N ions) c) increase the conductivity of selectively patterned areas of the organic thin film possibly by modifying the -orbital stacking of the aromatic rings. This effects is also stable with time (up to 2000 hours after the irradiation) and is induced by both 14N+ and with Ne+ ions. (figure 1) The large contact resistance RC, in organic electronics is one of the major issues in the improvement of the device performance, particularly important for OFETs with short channel length. Some methods to reduce RC have been proposed, based either on the introduction of self assembled monolayers at the metal/organic interface or on chemical treatment of the metal electrode prior to the organic deposition. However, these methods are rather demanding to implement in term of large scale reliable fabrication processes. Since ion irradiation has proven to effectively increase the current that flows in pentacene layers (over 5 orders of magnitude), we want to exploit this effect to reduce the RC in OFETs by selectively irradiating the electrical contact areas, thus locally decreasing the material conductivit