White luminescence characteristics of red/green silicate phosphor-glass thick film layers printed on glass substrate

Remote phosphor thick film layers consisting of red/green silicate phosphors embedded in a glass matrix were investigated in terms of the feasibility of a printing process onto a soda lime silicate glass substrate and the resultant performance of white luminescence. Densification of the phosphor layers via a viscous flow of the glass matrix at a low temperature of 400 °C was a key element of the success since the low temperature avoids chemical degradation of the phosphors. Photoluminescence and luminous efficacy were dependent on the relative content of the red/green phosphors. As an optimal example, the thick film containing 30 wt% red and 70 wt% green phosphors demonstrated the best efficiency of ~55.1 lm/W with excellent chromaticity coordinates.