A novel plastic substrate for flexible displays was developed. The substrate consisted of a polycarbonate (PC) base film coated with a gas barrier layer and a transparent conductive thin film. PC with ultra-low intrinsic birefringence and high temperature dimensional stability was developed for the base film. The retardation of the PC base film was less than 1 nm at a wavelength of 550 nm (film thickness, 120 mu m). Even at 180 degrees C, the elastic modulus was 2 GPa, and thermal shrinkage was less than 0.01%. The surface roughness of the PC base film was less than 0.5 nm. A silicon oxide (SiO(x)) gas barrier layer was deposited on the PC base film by a roll-to-roll DC magnetron reactive sputtering method. The water vapor transmission rate of the SiO(x) film was less than 0.05 g/m(2)/day at 40 degrees C and 100% relative humidity (RH), and the permeation of oxygen was less than 0.5 cc/m(2) day atm at 40 degrees C and 90% RH. As the transparent conductive thin film, amorphous indium zinc oxide was deposited on the SiO(x) by sputtering. The transmittance was 87% and the resistivity was 3.5 x 10(-4) ohm cm. (C) 2009 Elsevier B.V. All rights reserved.