NOVELTY - The device i.e. organic thin film transistor (OTFT) (10), has an organic thin film layer (20) with a side for implantation of ions. An end of the film layer is in contact with a electrode i.e. source electrode (16), and other end of the film layer is in contact with another electrode i.e. drain electrode (18), where the layer is modified by ion implantation into the side with a selected dose of ions with selected energy. The organic thin film layer is in contact with the former electrode and the latter electrode.    USE - Organic thin film device i.e. OTFT such as pentacene OTFT (all claimed), for controlling current flow between a source electrode and a drain electrode under imposed bias. Can also be used for an LED, a solar cell and a radio frequency identification (RFID).    ADVANTAGE - The device prolongs service life of the OTFT without increasing thickness of the OTFT. The ion implantation can be safely carried out on fully operational devices, and the implantation modifies the structure of the top portion of the organic thin film layer. The implantation produces a barrier that reduces sensitivity to oxygen and water vapor and stabilizes carrier mobility and device threshold voltage over an extended operational lifetime in the atmosphere. The device can selectively pattern exposed and modified areas of the organic thin film layer without lithographic mask, thus allowing to locally reduce contact resistance of the organic thin film layer with controlled reproduction of the desired patterns, and hence enhancing carrier injection efficiency and improving performance of the device electrodes that are fabricated.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for increasing the operating lifetime of an organic thin film device.    DESCRIPTION OF DRAWING(S) - The drawing shows a cut-away perspective view of an organic thin film device.    OTFT (10)    Doped silicon substrate (12)    Source electrode (16)    Drain electrode (18)    Organic thin film layer (20)