Fluorescent composition having the ability to change wavelengths of light, shaped article of said composition as a light wavelength converting element, and device for converting optical energy to electrical energy using said element

摘要

A fluorescent composition consisting essentially of (1) a polymerhaving a solubility parameter of at least about 9, such as polyethylene terephthalate etc., and;(2) one or more organic fluorescentsubstances, at leastone of said fluorescent substances showing difficult solubility, such as anthraquinonic pigments, such that when 0.5 part by weight of said at least one fluorescent substance and 100 parts by weight of polypropylene are mixed in the molten state at 300°C for 10 minutes and formed into a film having a thickness of about 1 mm, the film has a non-transmission index ETi (%), as defined by the following equation, of at least 7,wherein EAs is the percent light absorption of said film at 800 nm, and EAb is the percent light absorption at800 nm of a film of polypropylene having a thickness of about 1 mm,;said fluorescent composition being characterized by the fact that when it is formed into a film having a thickness of about 1 mm,the film has a non-transmission index PTi (%), as defined by the following equation, of not more than 10,wherein PAs is the percent light absorption at 800 nm of said film of the fluorescent composition, and PAb is the percent light absorption at 800 nm of a film having a thickness of about 1 mm of the polymer in the fluorescent composition.;Preferably, the composition is of a non-radiation type and contains at least two organic fluorescent substances, at least one of which shows difficult solubility, and at least two of which are such that the emission spectrum of one organic fluorescent substance has a wavelength common to the absorption spectrum of another organic fluorescent substance.;A shaped article composed of the composition is useful for light wavelength conversion.