Crystal structure and luminescence properties of (Ca_2.94−xLu_xCe_0.06)(Sc_2−yMg_y)Si₃O₁₂ phosphors for white LEDs with excellent colour rendering and high luminous efficiency

Abstract

Lu-modified (Ca 2.94−x Lu x Ce 0.06)(Sc 2−y Mg y)Si 3 O 12 (CLSMS : Ce 3+) yellow emitting phosphors are prepared by a solid-state reaction. Controllable luminescent intensity and emitting colour are studied as a function of Lu and Mg contents. Fixing the Mg content to be 1, the effect of Lu content on crystal phase formation, luminescence properties and temperature characteristics is studied. It is revealed that the Lu-induced luminescent enhancement is the result of an increase in absorbance of Ce 3+ rather than the internal quantum efficiency. Intense and broadband emission is realized by controlling the Lu content to obtain a pure CLSMS crystal phase. The maximum luminescence intensity is obtained at x = 0.54, which is as high as 156% of the Lu-free phosphor. The Lu-containing phosphor also exhibits better temperature characteristics for its big activation energy (0.20 eV) than the Lu-free one (0.18 eV). Combining the present phosphor with a blue light-emitting diode (LED) chip, a white LED with an excellent colour rendering index R a of 86 and a high luminous efficiency of 86 lm W −1 is obtained. The results of the present study demonstrate that the CLSMS : Ce 3+ phosphors show a good performance and are attractive candidates for commercial applications when used in white LEDs.

Efficient Near-Infrared Downconversion and Energy Transfer Mechanism of Ce3+/Yb3+ Codoped Calcium Scandate Phosphor

“…The Ce 3+ emission can be decomposed into two Gaussian bands centered at about 511 nm (19 570 cm –1 ) and 563 nm (17 762 cm –1 ), which are attributed to the transitions from the lowest Stark level of the 5d excited state to different Stark levels ( 2 F 5 / 2 and 2 F 7 / 2 ) of the 4f ground state of Ce 3+ , respectively. The energy difference is about 1808 cm –1 , which is very close to the splitting of the 4f ground state of Ce 3+ ion . In the NIR region (900–1100 nm), a strong emission band around 1000 nm is observed for the Ce 3+ and Yb 3+ codoped samples, which is originated from the Yb 3+ : 2 F 5/2 → 2 F 7/2 transition.…”

Origin and Luminescence of Anomalous Red-Emitting Center in Rhombohedral Ba9Lu2Si6O24:Eu2+ Blue Phosphor

“…Phosphor-converted white LEDs are widely applied in illumination and display fields due to their advantages of energy saving, high efficiency, long lifetime, etc. , Phosphors play important roles in determining the performances of white LEDs, because they convert the light emitted from near-UV (NUV) or blue LEDs into white light. − For the NUV-based white LEDs, blue phosphor is a critical item, as the blue light not only participates in the synthesis of white light but also can be used as an excitation light for green and/or red phosphors. Currently, the emission light of efficient NUV-LED chips is around 400 nm.…”

Luminescence in external dopant-free scandium-phosphorus vanadate solid solution: a spectroscopic and theoretical investigation

“…as the luminescent center, or the activators coupled by arrangement of these RE and/or non-RE ions. [1][2][3][4][5][6][7] Besides, some solid solutions, such as (La,Gd)Sr 2 AlO 5 :Ce 3+ , 1 Ca 1Àx Li x Al 1Àx Si 1+x N 3 :Eu 2+ , 2 La 2 Mg (1Àw) Zn w TiO 6 :Bi 3+ ,Mn 4+ , 4 and (Ca 1Àx Sr x ) 16 Si 17 N 34 :Eu 2+ , 6 are found to show unexpected photoluminescence (PL) properties, which include, for instance, the enhanced PL intensity and/or the improved thermally induced PL quenching stability. However, RE-and non-RE-free inorganic solid solutions, which exhibit spectral tuning, enhanced PL intensity, and improved thermal PL stability simultaneously, have still not been reported so far.…”