other than cucl were observed precipitated the high molecular compound cubr composite film thus obtained had a sufficiently small precipitate particle diameter and thus was transparent and light yellowish the absorption spectrum of the film is shown in fig6 the measurement of absorption spectrum was conducted at room temperature as a result a z 12 exciton absorption sub band structure of cubr was definitely observed at 410 nm a z 3 exciton absorption sub band structure of cubr was definitely observed at 390 nm as indications of the comparison between absorption by exciton and other undesirable absorptions abs exciton abs 500 nm abs exciton abs 450 nm and abs exciton abs 400 nm were calculated as in example 1 the results are set forth in table 2 the procedure of example 1 was followed to prepare a solution of a high molecular compound represented by the foregoing general formula 5 to the high molecular compound solution thus obtained was then added 0 22 g of cubr the mixture was then stirred to obtain a bluish green transparent solution the foregoing stirring steps were all conducted in an atmosphere of dried nitrogen the solution thus obtained was then spin coated onto a glass substrate in an atmosphere of dried nitrogen to obtain a light bluish green transparent film the film thus obtained was then subjected to heat treatment at a temperature of 250 u00b0 c under a pressure of 1 u00d7 10 5 torr for 30 minutes the film thus treated was then examined for the presence of precipitate by x ray diffractometry as a result it was confirmed that the foregoing heat treatment had caused the precipitation of cubr see fig7 no crystals other than cubr were observed precipitated the high molecular compound cubr.