Innovative transparent electrode for flexible displays

Abstract

This paper presents a new transparent electrode (TE) for flexible displays and energy saving windows. The TE is a room temperature vacuum-deposited multi-layer thin-film system. Both highly transparent rigid materials including glass and ceramics as well as flexible polymeric materials such as polyethylene terephthalate (PET) and polypropylene can serve as substrates for the TE. The TE is deposited as a flexible coating that can be rolled around a 0.5cm diameter cylinder with little or no reduction in electrical conductivity and that can assume pre-extension states after an applied stress is relieved. The TE exhibits high visible transmittance without color. The transmission spectrum of the TE, which matches the eye sensitivity curve, allows the viewing of true background colors through the coating. The photopic transmittance of the TE is 88% and it is a UV inhibiter. The new transparent conductor has 3-5 Ohm/sq of sheet resistance. The environmental stability of the TE was evaluated in a wedeometer with the coating on a PET substrate withstanding 150 hours at 50^oC, 95% humidity, and ultraviolet (UV), without changing its original performance. The coating can be patterned using standard etching procedures.. In this paper, the properties of the TE are compared with those of common transparent conductive oxides (TCO) including ITO, ZnO: Al and SnO2:F. In addition to the technical description, the paper analyzes potential markets and applications of the TE with emphasis on the replacing current TCO coatings, specifically ITO for flexible display electrode and energy saving window applications.