An Intense Green/Yellow Dual-Chromatic Calcium Chlorosilicate Phosphor Ca[sub 3]SiO[sub 4]Cl[sub 2]:Eu[sup 2+]–Mn[sup 2+] for Yellow and White LED

Abstract

A series of intense green/yellow phosphors Ca 3 SiO 4 Cl 2 :Eu 2+ ,Mn 2+ was synthesized by a high-temperature solid-state reaction. Their luminescent properties were characterized by means of powder diffuse reflection, photoluminescence excitation and emission spectra, and lifetime and temperature-dependent emission spectra in the temperature range of 10-450 K. The phosphors Ca 3 SiO 4 Cl 2 :Eu 2+ ,Mn 2+ show intense broad absorption bands between 250 and 450 nm, matching well with the near-ultraviolet ͑380-420 nm͒ emission band of InGaN-based chips, and exhibit two dominating bands situated at 512 and 570 nm, ascribed to the allowed 5d → 4f transition of the Eu 2+ ion and the 4 T 1g ͑ 4 G͒ → 6 A 1g ͑ 6 S͒ transition of the Mn 2+ ion, respectively. The lifetime of the Eu 2+ ion decreases with increasing the concentration of the Mn 2+ ion, strongly supporting an efficient energy transfer from Eu 2+ to Mn 2+. By combining with near-ultraviolet ͑ϳ395 nm͒ InGaN chips, intense yellow light-emitting diodes ͑LEDs͒ with a much lower ultraviolet light leakage were successfully fabricated based on the Ca 3 SiO 4 Cl 2 :Eu 2+ ,Mn 2+ phosphor, and intense white LEDs were made based on a blend of blue chlorophosphate phosphor and the green/yellow phosphor Ca 3 SiO 4 Cl 2 :Eu 2+ ,Mn 2+. The color coordinate, correlated color temperature T c , general color-rendering index R a , and luminous efficiency of the fabricated white LEDs are ͑0.3281, 0.3071͒, 6065 K, 84.5, and 11 lm/W, respectively.

Eu2+–Mn2+ energy transfer in white-light-emitting T-phase (Ba,Ca)2SiO4:Eu2+, Mn2+ phosphor

“…5. Similar phenomena were observed in other Eu 2 + /Mn 2 + -codoped phosphors and were attributed to Eu 2 + /Mn 2 + close paring [7,[14][15][16][17]. Here, we suggest the simple reason for this interesting observation is the local inhomogeneous distribution of Eu 2 + ions around Mn 2 + sites which can give rise to the perturbation of these sites and thus violation of the Mn 2 + selection rules and enhance the Mn 2 + red emission.…”

Photoluminescence properties and energy-transfer of thermal-stable Ce3+, Mn2+-codoped barium strontium lithium silicate red phosphors

“…This nonradiative transition probability by thermal activation is strongly dependent on temperature, resulting in the decrease of the emission intensity [45]. Comparatively, the thermal quenching temperature of Mn 2+ was higher than that of Ce 3+ , indicating a weaker electron-phonon interaction or higher thermal activation energy in the host [19].…”

The synthesis and photoluminescence of a single-phased white-emitting NaAlSiO 4 : Ce 3+ , Mn 2+ phosphor for WLEDs

“…The white light is usually attributed to different activators or one kind of activator at different crystal sites [9][10][11][12]. Recently, the single-phased color-tunable with white light-emitting phosphors have been obtained by co-doping Ce 3+ and Mn 2+ in proper hosts, such as Ca 2 SrAl 2 O 6 [8], NaCaBO 3 [13], and Ca 2 Gd 8 (SiO 4 ) 6 O 2 [14].…”