Preferential Neighboring Substitution-Triggered Full Visible Spectrum Emission in Single-Phased Ca_10.5–xMg_x(PO₄)₇:Eu²⁺ Phosphors for High Color-Rendering White LEDs

Abstract

Manipulating the distribution of rare-earth activators in multiple cation lattices can achieve versatile color output for single-phased phosphor-converted white light-emitting diodes (LEDs). However, successful cases are barely reported, owing to the uncertain distribution of rare-earth activators and the special combination of three primary colors for white LEDs. Herein, we took whitlockite β-Ca(PO) as a multiple cation lattice host to manipulate the redistribution of Eu activators, and the surprising Mg-guided redistribution of Eu activators among different Ca sites is reported for the first time to regulate the photoluminescence (PL) behavior in series CaMg (PO):Eu phosphors. The preferential neighboring substitution of smaller Mg cations in Ca(5) and Ca(4) sites triggers a discontinuous evolution of local structure along c axis and induces covalent variable Ca(1), Ca(2), and Ca(3) cation sites for the accommodation of Eu activators. The unique optical feature enables the single-phased CaMg(PO):Eu phosphor-converted white LED to exhibit quite high color-rendering index R (85) and R (91) values. The preferential neighboring-cation substitution reported here can not only manipulate the migration of Eu activators among different cation sites for tunable PL properties, but also carve out a new way for next-generation high-quality solid-state lighting.

Trap distribution and photo‐stimulated luminescence in LaSrAl3O7:Eu2+ long‐lasting phosphors for optical data storage

“…The PLE, PL, together with DR spectra of LSA:0.02Eu 2+ are shown in Figure A. Two distinct characteristic excitation bands of Eu 2+ ions ranging from 250 to 350 nm are observed, which originate from the ground state 4 f 7 to the higher‐lying and lowest lying 4 f 6 5 d 1 states transition of Eu 2+ . It is also found that the PLE is in accordance with the DR spectrum.…”

“…Two distinct characteristic excitation bands of Eu 2+ ions ranging from 250 to 350 nm are observed, which originate from the ground state 4f 7 to the higher-lying and lowest lying 4f 6 5d 1 states transition of Eu 2+ . [32][33][34][35] It is also found that the PLE is in accordance with the DR spectrum. From the inset of Figure 4D, the sample can emit intense green light under the UV (320 nm) excitation, and the maximum emission peaks at 518 nm with a full width at half maximum (FWHM) of approximately 1351 cm −1 .…”

High-throughput DFT screening enables the discovery of a super-broadband white-emitting phosphor for high-CRI white LEDs

“…The development of new high-performance phosphor materials will promote the advance of white LEDs and thus further extend the impact of solid-state lighting technology in lighting, displays and other applications. Currently, the white LEDs fabricated by using blue LED chips and YAG:Ce 3+ yellow phosphors suffer from low color-rendering index (CRI < 80) and high correlated color temperature (CCT ≈ 6494 K) owing to the cyan gap and lack of the red-light component [4,5], whereas the alternative white LED devices based on the combination of ultraviolet (UV) LED chips with tricolor (red, green, and blue) phosphors encounter serious problems such as inevitable energy reabsorption and color variation [6][7][8][9]. Accordingly, it is urgent and challenging to discover new high-quality single-phased white-light-emitting materials with fullvisible-spectrum emission to construct high-CRI white LEDs.…”

A broadband emitting Sr8MgGa(PO4)7:Eu2+ phosphor for application in white light-emitting diodes with excellent color rendering index

“…Based on the above reasons, excellent performance and broadband emitting yellow phosphors [13][14][15][16][17][18] were prepared and investigated in detail by many researchers in recent years. For example, Wang's group reported a yellowemitting Li 2 CaSi 2 N 4 :Ce 3+ nitride phosphor with tunable extra-broad emitting and zero-thermal-quenching property [19].…”