Realizing Wide‐Gamut Human‐Centric Display Lighting with K₃AlP₃O₉N:Eu²⁺

Abstract

Computers, televisions, and smartphones are revolutionized by the invention of InGaN blue light‐emitting diode (LED) backlighting. Yet, continual exposure to the intense blue LED emission from these modern displays can cause insomnia and mood disorders. Developing “human‐centric” backlighting that uses a violet‐emitting LED chip and a trichromatic phosphor mixture to generate color images is one approach that addresses this problem. The challenge is finding a blue‐emitting phosphor that possesses a sufficiently small Stokes’ shift to efficiently down‐convert violet LED light and produce a narrow blue emission. This work reports a new oxynitride phosphor that meets this demand. K3AlP3O9N:Eu2+ exhibits an unexpectedly narrow (45 nm, 2206 cm−1), thermally robust, and efficient blue photoluminescence upon violet excitation. Computational modeling and temperature‐dependent optical property measurements reveal that the narrow emission arises from a rare combination of preferential excitation and site‐selective quenching. The resulting chromaticity coordinates of K3AlP3O9N:Eu2+ lie closer to the vertex of the Rec. 2020 than a blue LED chip and provides access to ≈10% more colors than a commercial tablet when combined with commercial red‐ and green‐emitting phosphors. Alongside the wide gamut, tuning the emission from the violet LED and phosphor blend can reduce blue light emissions to produce next‐generation, human‐centric displays.

Colossal Chromatic Shift in the Ba2Ca2B4O10:Ce3+ Phosphor

“…Site-selective quenching is a curious phenomenon that is occasionally observed in phosphors. 19,50,51 Not only does it affect the luminescence efficiency but it can also significantly impact the phosphor's observed emission color, as observed here. A closer examination of the optical properties in (Ba 1.97 Ce 0.02 )Ca 2 B 4 O 10 shows a significant temperature-induced blue shift of the emission spectra, further impacting the phosphor's emission color.…”

“…However, BAM:Eu 2+ still experiences a decrease in luminescence intensity over prolonged usage due to oxidation of the luminescent center from Eu 2+ to Eu 3+ . The material is also sensitive to long-term water exposure, resulting in a red shift accompanied by a broadening of the emission spectrum …”

“…18 The material is also sensitive to long-term water exposure, resulting in a red shift accompanied by a broadening of the emission spectrum. 19 Additional issues arise in devices containing a trichromatic phosphor blend when considering the operating temperatures of modern high-power pc-LED lights. Temperature-driven fluctuations can cause significant changes in the vibrational molecular dynamics and electron−phonon interactions within the rare-earth−host structure combination, leading to perturbations in the emission intensity, full width at halfmaximum (fwhm), and peak position (λ em,max ) of each phosphor.…”

Non-concentration quenching and energy transfer enhanced green emission in Ca8SrGd(PO4)7:Eu2+,Tb3+ for near-UV white LEDs with a high color rendering index

“…Therefore, it is desirable to explore green phosphors that can be excited using near-ultraviolet light. [12][13][14] Some green phosphors containing Ce 3+ and Eu 2+ ions, such as La 3 Br(SiS 4 ) 2 :Ce 3+ and BaSi 7 N 10 :Eu 2+ , have limitations due to their structural instability and harsh synthesis conditions. 15,16 On the other hand, Tb 3+ acts as a typical activator for green emission, resulting from its typical 5 D 4 -7 F 5 transition (B545 nm).…”

High performance of broad excitation and narrow emission green phosphor NaAl11O17:Eu2+, Mn2+for backlight displays

“…Continuous blue LED irradiation could affect the production of melatonin, thus severely compromising human slumber and mood. [1][2][3] Based on the purpose of human-centered lighting, a method to convert the devices to a violet LED coupled with trichromatic (red, green and blue) phosphor mixtures is presented to minimize the negative effects of continuous blue LED chip irradiation to a great extent. [4][5][6][7][8] The development of phosphors, indispensable materials in WLED backlight technology, with excellent luminescence properties is important.…”