Patent ID: 8907558
Filing Date: 2014-12-09
Classification: C09K,H01L,Y02B

Abstract:
1. A white light emitting device, comprising: a light emitting element having a peak wavelength in a wavelength range of 430 nm or more and 460 nm or less; and a fluorescent layer formed above the light emitting element and contains a red fluorescent material and a green-yellow fluorescent material, wherein when a peak wavelength of a fluorescent material, a full width at half maximum of light emitted from a fluorescent material, an effective wavelength width of a spectrum for light emitted from a fluorescent material, and an external quantum efficiency of a fluorescent material are respectively denoted by λp, FWHM, EWW, and η, the red fluorescent material has the characteristics of: the green-yellow fluorescent material has the characteristics of: the red fluorescent material has a composition of formula (1): wherein, in formula (1), A is at least one element selected from K (potassium) and Cs (cesium), M is at least one element selected from Si (silicon) and titanium (Ti), and a, b, and s are numerical values which respectively satisfy 1.7≦a≦2.1, 5.3≦b≦6.3, and 0<s≦0.05, the green-yellow fluorescent material has a composition of formula (2) or (3): wherein, in formula (2), c, d, u, v, and w represent numerical values which respectively satisfy 2.8≦c≦3.2, 11.5≦d≦12.5, 0≦u≦0.2, 0.02≦v≦0.15, and 0≦w≦0.3, wherein, in formula (3), e, f, x, y, and z represent numerical values which respectively satisfy 1.9≦e≦2.1, 3.6≦f≦4.1, 0.15≦x≦0.4, 0≦y≦0.1, and 0<z≦0.15, and wherein the white light emitting device has an Ra value from 86 to 90 and a white efficiency from 196 to 218 lm/excitation light W.