Advancing Human-Centric LED Lighting Using Na₂MgPO₄F:Eu²⁺

Abstract

The proliferation of energy-efficient light-emitting diode (LED) lighting has resulted in continued exposure to blue light, which has been linked to cataract formation, circadian disruption, and mood disorders. Blue light can be readily minimized in pursuit of “human-centric” lighting using a violet LED chip (λem ≈ 405 nm) downconverted by red, green, and blue-emitting phosphors. However, few phosphors efficiently convert violet light to blue light. This work reports a new phosphor that meets this demand. Na2MgPO4F:Eu2+ can be excited by a violet LED yielding an efficient, bright blue emission. The material also shows zero thermal quenching and has outstanding chromatic stability. The chemical robustness of the phosphor was also confirmed through prolonged exposure to water and high temperatures. A prototype device using a 405 nm LED, Na2MgPO4F:Eu2+, and a green and red-emitting phosphor produces a warm white light with a higher color rendering index than a commercially purchased LED light bulb while significantly reducing the blue component. These results demonstrate the capability of Na2MgPO4F:Eu2+ as a next-generation phosphor capable of advancing human-centric lighting.

Ca[B8O11(OH)4] : Eu2+ – A Highly Efficient Deep Blue‐Emitting Phosphor Prepared by Low‐Temperature Self‐reduction

“…The PLQY of CBH : 2 %Eu 2+ is higher than those of the perovskite type of CsPbBr x Cl 3−x (PLQY=89 %), [61] the UCr 4 C 4 type of RbNa 3 (Li 3 SiO 4 ) 4 : Eu 2+ (PLQY=53 %), [15] commercial phosphor of BaMgAl 10 O 17 : Eu 2+ (PLQY=92.4 %) [14] and other aluminate of BaAl 12 O 19 : Eu 2+ (PLQY=90 %), [59] borates of Ba 3 Y 2 B 6 O 15 :Ce 3+ (PLQY=84 %), [62] BaAlBO 3 F 2 : Eu 2+ (PLQY=76 %), [63] Ba 2 (Y 1−x Lu x ) 5 B 5 O 17 :Ce 3+ (x=0∼1) (PLQY=90 %), [64] and phosphate of Sr 4.99 (PO 4 ) 3 Cl:0.01Eu 2+ (PLQY=80.5 %) [16] . The external quantum efficiency (EQE) of CBH : Eu 2+ is measured to be 31.1 %, which is higher than those of the recently reported blue phosphor of (Na 2−2x Eu x )MgPO 4 F (EQE=18.1 %), [65] Na 0.58(4) K 0.42(4) Li 3 SiO 4 : Eu 2+ (EQE=30.0 %), [66] and KMg 4 (PO 4 ) 3 : Eu 2+ (EQE=18.6 %), [67] but lower than those of K 2 YZr(PO 4 ) 3 : Eu 2+ (EQE=40 %), [68] and Sr 3.61(1−x) Eu 3.61 xLiSi 14.27 Al 5.61 O 6.19 N 23.25 (EQE=37 %), [69] and commercial BAM : Eu 2+ phosphor (EQE=37 %) [67] …”

Enabling Wide-Gamut Human-Centric Display Lighting

“…This approach has already been successfully applied to create a prototype humancentric warm white LED light bulb with better color rendering than a commercial bulb with a minimal blue light component. 19 Curiously, a similar approach for LED-based display backlighting has not yet been discussed, but it undoubtedly needs to be addressed considering that American children spend an estimated 7.5 hours daily looking at screens. 20 One factor limiting the widespread conversion to human-centric displays is the lack of phosphors that possess the small Stokes' shift necessary to achieve blue emission upon violet excitation.…”

Role of Architectural Design in Creating Circadian-Effective Interior Settings

“…The concept of HCL is derived from the evolution of the intensity and CCT of natural light throughout the day, and how it stimulates humans' circadian rhythms [83,84]. It is focused on manipulating light-related factors (i.e., intensity, spectrum, directionality, and duration) within the built environment to benefit human health and comfort [82].…”