Method of fabricating substrateless thin film field-effect devices and an organic thin film transistor obtainable by the method

Abstract

A method for the manufacture of a thin-film field-effect device comprising, on a mechanical support layer, source and drain electrodes (S, D), a layer of semiconductor material (SC) for the formation of a conduction channel, and a gate electrode (G) insulated from the channel region, is described. The method provides for the use of a mechanical support layer in the form of a film (INS) of flexible, electrically-insulating material; for the formation of the source and drain electrodes (S, D) in accordance with a predetermined configuration on a first surface of the insulating film; and for the formation of the gate electrode (G) on the opposite surface of the insulating film (INS) in accordance with a predetermined configuration complementary with the configuration of the source and drain electrodes (S, D), that configuration being achieved by a lithographic technique by selective masking determined by the source and drain electrodes (S, D) which are formed on the first surface of the film (INS).

1 . An organic thin-film, field-effect transistor comprising, on a mechanical support layer including a flexible, transparent film (INS) of electrically-insulating material, a pair of source and drain electrodes (S, D) formed spaced apart on a first surface of the film (INS), and a layer of organic semiconductor material (SC) disposed between the electrodes (S, D) for the formation of a conduction channel the resistance of which is modulated by the application of a predetermined control voltage to a gate electrode (G) which is insulated from the channel region and formed on the part of the surface of the film (INS) opposite to the surface carrying the source and drain electrodes (S, D) in an arrangement complementary with that of the source and drain electrodes (S, D). 
     
     
         2 . A transistor according to  claim 1  in which the flexible, transparent, electrically-insulating film (INS) is a polyethylene terephthalate film. 
     
     
         3 . A transistor according to  claim 2  in which the thickness of the film (INS) is less than one micron. 
     
     
         4 . A sensor device for detecting predetermined chemical species which are present in the surrounding environment, having a flexible mechanical structure and comprising a thin-film field-effect transistor according to  claim 1  in which the gate electrode (G) or the layer of semiconductor material (SC) comprises at least one layer of molecules which are selective with respect to the chemical species to be detected, or at least one layer of molecules which are selective with respect to the chemical species to be detected is interposed between the gate electrode (G) and the insulating film (INS), and is chemically or physically anchored thereto. 
     
     
         5 . A deformation sensor device having a mechanically flexible structure and comprising a thin-film field-effect transistor comprising on a mechanical support layer including a flexible, transparent film (INS) of electrically-insulating material, a pair of source and drain electrodes (S, D) formed spaced apart on a first surface of the film (INS), and a layer of organic semiconductor material (SC) disposed between the electrodes (S, D) for the formation of a conduction channel the resistance of which is modulated by the application of a predetermined control voltage to a gate electrode (G) which is insulated from the channel region and formed on the part of the surface of the film (INS) opposite to the surface carrying the source and drain electrodes (S, D) in an arrangement complementary with that of the source and drain electrodes (S, D).