NOVELTY - The optical-functional thin film element (1) has an optical-functional thin film (4) interposed between electrodes (3,5). Refractive-index adjusted layers (6-8) are formed by adjusting the refractive index of interface (I) of electrode (I) and thin film, interface (II) of thin film and electrode (II), and/or interface (III) of electrode (I) and air.    USE - Optical-functional thin film element is used for displays, illuminating components, solar cells (all claimed), light sources used for optical communication, meters, signals, indicators, and field emission displays used in televisions, mobile telephones, electronic paper, personal computers, and motor vehicles.    ADVANTAGE - The optical-functional thin film element has improved light-emission performance.    DETAILED DESCRIPTION - The optical-functional thin film element (1) has an optical-functional thin film (4) interposed between electrodes (3,5). Refractive-index adjusted layers (6-8) are formed by adjusting the refractive index of interface (I) of electrode (I) and thin film, interface (II) of thin film and electrode (II), and/or interface (III) of electrode (I) and air. The optical-functional thin film consists of pi -conjugated-type material chosen from quinolinol derivative, fluorene derivative, phthalocyanine derivative, triphenyldiamine derivative, polyparaphenylene derivative, oxadiazole derivative, pyrazoline derivative, polythiophene derivative, poly(N-alkylcarbazole) derivative, polyphenylacetylene derivative, polyphenylene ethynylene derivative, and polyphenylene butadiynylene derivative. The electrode(s) contains doped polypyrrole, doped polyaniline, doped polythiophene, doped polyacetylene, doped polyisothianaphthene, and/or their derivatives. An INDEPENDENT CLAIM is included for manufacture of optical-functional thin film element.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view of the optical-functional thin film element. (Drawing includes non-English language text)    Optical-functional thin film element (1)    Electrodes (3,5)    Optical-functional thin film (4)    Refractive-index adjusted layer (6-8)    Power supply (9)