Mie-scattering theory WLEDs Color rendering index luminous efficacy Dual-layer phosphor Luminous efficacy Mn2+ Triple-layer phosphor color rendering index dual-layer phosphor (Y Ba2Li2Si2O7:Sn3+ Bright efficacy Color quality scale Dual-layer remote phosphor geometry Gd)BO3:Eu Luminous flux MgSr3Si2O8:Eu2+ Mie-scattering NaB2O4:Mn2+ Remote phosphor SrBaSiO4:Eu2+ White LED color quality color uniformity lambert-beer law luminous flux mie-scattering theory remote-phosphor remote phosphor package triple-layer phosphor triple-layer structure