Plastic Electronic Devices Through Line Patterning of Conducting Polymers

A novel method for the preparation of transparent conducting‐polymer patterns on flexible substrates is presented. This method, line patterning, employs mostly standard office equipment, such as drawing software, a laser printer, and commercial overhead transparencies, together with a solution or dispersion of a conducting polymer. The preparation of a seven‐segment polymer‐dispersed liquid‐crystal display using electrodes of the conducting polymer poly(3,4‐ethylenedioxythiophene) doped with poly(4‐styrene sulfonate) (PEDOT/PSS) is described in detail. Furthermore, a method to fabricate an eleven‐key push‐button array for keypad applications is presented. Properties of the electrode films and patterns are discussed using microscopy images, atomic force microscopy, conductivity measurements, and tests of film stability. The method of “line patterning” for producing transparent conducting‐polymer patterns employs standard office equipment such as a laser printer and commercial overhead transparencies. A seven‐segment liquid‐crystal display (see Figure) and an 11‐key keypad, prepared from a common conducting‐polymer blend, are described in detail.