Example 4
A suitable amount of the toluene solution of the CsPbBr3 quantum dots (the CsPbBr3 quantum dots are about 5 mg) in Preparation Embodiment 4, 20 ml of a toluene solvent, and 0.5 g of polyvinyl butyral are taken, and stirred and mixed in glassware at 80 degrees Celsius, so that the CsPbBr3 quantum dots are dispersed in swollen polyvinyl butyral, after the toluene is removed, a wavelength converting film with a thickness of about 300 microns is prepared by compressing in a mold.
A suitable amount of the toluene solution of the CsPbBr3 quantum dots (the CsPbBr3 quantum dots about 0.5 g) in Preparation Embodiment 4 and 500 g of a UV-curable acrylic resin are taken and mixed, an organic solvent is removed in vacuum, coating is performed by using a blade coater, and ultraviolet light curing is performed to prepare a wavelength converting film with a thickness of about 300 microns.
A suitable amount of the toluene solution of the CsPbBr3 quantum dots (the CsPbBr3 quantum dots are about 0.5 g) in Preparation Embodiment 4 and 500 g of a thermocuring epoxy resin are taken and mixed, an organic solvent is removed in vacuum, coating is performed by using a blade coater, and heat-curing is performed to prepare a wavelength converting film with a thickness of about 300 microns.
The wavelength converting films in Embodiment 4, Contrast Example 4-1, Contrast Example 4-2 and Contrast Example 4-3 are placed in an oven with a humidity of 95% and a temperature of 60° C., and 447 nm of a blue backlight source of which an intensity is 50 mW per square centimeter is used to illuminate, the brightness of the wavelength converting films are respectively tested at 0 h, 24 h, 48 h, 96 h, 168 h, 336 h, 672 h, and 1000 h, and the initial brightness of the wavelength converting film is marked as 1, ratios of the brightness at different times to the initial brightness are recorded, and test results are shown in Table 5. An instrument used to test the brightness is a PR-670 spectrophotometric radiometer.
It may be seen from Table 5 that compared with the existing common swelling method (Contrast Example 4-1), ultraviolet light curing acrylic resin (Contrast Example 4-2), and thermocuring epoxy resin (Contrast Example 4-3), after the wavelength converting film prepared by using the method (Embodiment 4) of dispersing the CsPbBr3 quantum dots in the molten polyvinyl butyral is aged for 1000 h in the oven with 95% of the humidity and 60° C. of the temperature, the ratios of the brightness and the initial brightness are respectively 0.98, 0.34, 0.33 and 0.56, namely the brightness of the wavelength converting film in Embodiment 4 is kept basically unchanged. It is indicated from the above that the fluorescent nanomaterial-polymer composite and the wavelength converting film prepared by this method have the excellent stability.
