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KxNa1-xLuS2:Eu2+ are wide-spectrum luminescent materials for white LEDs with an application potential for construction of a circadian light source. A simultaneous excitation of the sulfide KxNa1-xLuS2:Eu2+ by UV LED and blue LED it is possible at changing the intensity ratio of UV and blue LEDs to tune a coloured temperature of the resulting white light from the cold white to the warm white.
Description
CIE 1931 color coordinates calculated for samples under 390 nm excitation (cross marks) and 450 nm excitation (circles). Blue LED at 460 nm and UV LED at 395 nm were added for comparison. Dashed lines denote the colors available by mixing multiple materials under 390 nm resp. 455 nm excitation. Spectrum of the sample 4 is mixed with blue and UV excitation LEDs to show the resulting white light with CCT color temperatures of 3600 K and 5800 K.