its regeneration at a desired instant by temperature control i e thermal operation sulfides and silicates of zn were prepared to which a small amount of one of the metal elements cu mn b bi etc was added thin films and fine particles made of these materials accumulate and store light energy in a wavelength region from 1800 to 7000 u00e5 which they receive at a temperature under 50 u00b0 c at a desired instant after irradiation by light energy the light energy thus stored could be regenerated in the form of visible light by raising the temperature of the thin films and fine particles of the aforementioned materials to a temperature which was equal to or higher than room temperature wavelength of this regenerated light was measured and it was found to be 5260 u00e5 results obtained with calcium sulfide to which a small amount of one of the aforementioned elements was added were similar to those previously described light energy was accumulated and stored at 50 u00b0 c light used for irradiation was solar light light was regenerated by raising the temperature to room temperature and the wavelength of the regenerated light was 4800 u00e5 results of experiments similar to those described above are summarized in table 3 in which column a indicates phosphors used column b the condition for storing and regeneration of light energy column c the wavelength region of the regenerated light and column d the wavelength at the peak of the regenerated light spectrum table 3______________________________________a b emission spectraphosphors temp u00b0 c c range d max peak______________________________________zn sub 2 sio sub 4 50 u2192 r t 4800 u02dc 7000 u00e5 5200 u00e5 zns 39 cu 50 u2192 r.