Novel Blue-Emitting Na_xCa_1-xAl_2-xSi_2+xO₈:Eu²⁺(x= 0.34) Phosphor with High Luminescent Efficiency for UV-Pumped Light-Emitting Diodes

Abstract

A novel blue-emitting phosphor, Na(0.34)Ca(0.66)Al(1.66)Si(2.34)O(8):Eu(2+) (NCASO:Eu(2+)), was prepared by a wet chemical synthesis method based on the hydrolysis of tetraorthosiliate (TEOS) and confirmed the formation of NCASO:Eu(2+) from Rietveld analysis. Photoluminescence (PL) results showed that the phosphor can be efficiently excited by UV light from 250 to 420 nm, and emitted bright broad blue emission, which has maximum intensity at around 445 nm. Under 365 nm excitation, the PL emission intensity area of optimized NCASO:Eu(2+) was found to be 99.72% of that of a commercial BaMgAl(10)O(17):Eu(2+) (BAM:Eu(2+)) phosphor. Moreover, the optical absorbance, internal quantum efficiency, and external quantum efficiency of NCASO:Eu(2+) were calculated to be 112%, 94%, and 105% of that of the commercial BAM:Eu(2+) phosphor, respectively. The WLEDs were fabricated using the blue NCASO:Eu(2+) phosphor, a green-emitting β-SiAlON:Eu(2+), and a red-emitting CaAlSiN(3):Eu(2+) phosphors with a near-UV chip. The WLED device exhibited an excellent color-rendering index R(a) of 94 at a correlated color temperature of 5956 K with CIE coordinates of x = 0.323, y = 0.335. These results suggest that NCASO:Eu(2+) is a promising blue-emitting phosphor for UV LED applications.

Solid-state reaction preparation and photoluminescence properties of Na2Ba6(Si2O7)(SiO4)2:Eu2+ phosphors

“…According to Liebau's nomenclature, this compound belongs to a mixed anion silicate and the structure of Na 2 Ba 6 (Si 2 O 7 )(SiO 4 ) 2 consists of a three-dimensional framework based on mixed tetrahedral and octahedral [14,15]. Si atoms in two sites are bonded with O atoms, forming a Si 2 O 7 dimer and two SiO 4 tetrahedral.…”

Single-phase white-emitting phosphors Ba3Ce(1−x−y)(PO4)3:xTb3+,yMn2+ and Ba3Ce(1−x−z)(PO4)3:xTb3+,zSm3+: structure, luminescence, energy transfer and thermal stability

“…One of the methods for achieving white emission is co-doping different ions in a single-phase compound. [5][6][7] This can not only overcome the shortcomings of high correlated color temperature and low color rendering index, but also avoid reabsorption in the host. [8][9][10][11] Generally, energy transfer plays an important role in the optical properties of co-doped luminescent materials, from which we can obtain a tunable color or white emission.…”

Tunable emission and the systematic study on energy-transfer properties of Ce3+- and Tb3+-co-doped Sr3(PO4)2 phosphors

“…shows low-color-rendering index (Ra \ 80), high color temperature (T c [ 7000 K) and thermal quenching because of the deficiency of red light component. It usually results in chromatic aberration, poor color stability with longer working time and the emitting color cannot meet the operating requirements of indoor lighting well [8][9][10][11]. Doubly doped luminescent material based on ET is considered as an effective alternative way for fabricating phosphor-converted (pc) w-LEDs to get higher-color-rendering index and tunable color temperature.…”