Porous Ce:YAG ceramics with controllable microstructure for high‐brightness laser lighting

Abstract

In order to meet the increasing demand for high‐power laser diode lighting and displays, phosphor converters with high‐brightness and high‐directionality ought to be constructed to enhance the luminance and luminous efficacy. However, the pores formed during the sintering of phosphor ceramics affect the scattering effect and directionality of light. Therefore, porosity optimization and pore size regulation need to be explored. In this work, a series of Ce:YAG ceramics with various porosities and pore sizes were prepared. The influences of porosity and pore size on the microstructure, light confinement ability, and optical properties of Ce:YAG ceramics were studied. The ceramic phosphor with a porosity of 10 vol.% and a pore size of 3 μm exhibits a good spot confinement ability and shows a high luminous flux value of 3430 lm and a central luminance (1669 592 cd/m2) under blue laser excitation. The 10 vol.% Ce:YAG ceramic phosphor with a pore size of 5 μm has the highest emission intensity and gives a maximum luminous efficacy of 268 lm/W and a luminous flux of 4020 lm under 30 W/mm2 blue laser excitation. Thus, the porous Ce:YAG ceramics are expected to be a promising candidate for high‐brightness laser lighting and projection applications.

Patterned phosphor-in-glass films with efficient thermal management for high-power laser projection displays

“…It was found that PL and PLE spectral profiles of the samples remained almost invariable after co-sintering, which indicates that prepared PiGF maintains luminescent properties of the pristine phosphor. All PL and PLE spectra of them show typical broad emission/excitation bands from Ce 3+ /Eu 2+ :5d↔4f parity-allowed transitions [22,37,38]. The emission around 690-700 nm is caused by Cr 3+ emission attributed to 2E→4A transition in the Al 2 O 3 substrate [29].…”

“…From the perspective of the color converters, phosphors in silicone (PiS) commonly used in white LED will carbonize under high-power density laser excitation and become no longer applicable because of its poor heat resistance and low thermal conductivity [9,13,14]. In this context, three kinds of all-inorganic color converters-single crystals [15][16][17], transparent ceramics [18][19][20][21][22], and phosphors in glass (PiG) [23][24][25][26][27][28][29][30][31][32] have replaced phosphor-organic polymer binders, and become core materials for laser-driven lighting sources due to their robustness. By contrast, PiG and phosphor-in-glass film (PiGF) have advantages of cost-effective fabrication, flexible design, and tunable luminescence by mixing multi-phase phosphors.…”

High recorded color rendering performance of single-structured Ce,Mn:Y 3(Al,Sc) 2Al 3O 12 phosphor ceramics for high-power white LEDs/LDs

“…The fourth-generation solid-state lighting source (LEDs/LDs) has become the most promising lighting technology for its high efficiency, good stability, long working life, environmental protection and other advantages compared to traditional lighting structure [1][2][3][4][5]. Nowadays, the mainstream technical solution for white light generation is to combine blue LED/LD with phosphor conversion materials, and this new conversion materials mainly include phosphor ceramics (PCs), single crystals (SCs) and phosphor-in-glass (PIG) [6][7][8][9][10]. Among them, the preparation process for SCs is complex and costly, making it difficult to produce on a large scale.…”

Al2O3–Ce:YAG composite phosphor ceramics for white laser lighting: Novel preparation and regulatable properties

“…6 Compared with phosphors and phosphor glasses, Ce:YAG phosphor ceramics possess unique advantages and potentials, which have excellent thermal properties, good mechanical properties, and high chemical stability, as well as the advantages of adjustable microstructure and simple preparation process. [7][8][9][10] However, the pure-phase Ce:YAG phosphor ceramics face the problems of low blue light absorption efficiency and low thermal conductivity (9-14 W m −1 K −1 ), resulting in low luminous efficiency and thermal quenching with increasing blue LD power density for solid-state lighting application. 11,12 The effective strategy of adding the second-phase Al 2 O 3 as the scattering center in Ce:YAG phosphor ceramics has been proven to improve the luminous efficiency and the luminescence uniformity.…”

“…Moreover, Ce:YAG material is an integral part of solid‐state laser‐driven lighting due to its high quantum conversion efficiency and strong absorption ability in the blue light band 6 . Compared with phosphors and phosphor glasses, Ce:YAG phosphor ceramics possess unique advantages and potentials, which have excellent thermal properties, good mechanical properties, and high chemical stability, as well as the advantages of adjustable microstructure and simple preparation process 7–10 . However, the pure‐phase Ce:YAG phosphor ceramics face the problems of low blue light absorption efficiency and low thermal conductivity (9–14 W m −1 K −1 ), resulting in low luminous efficiency and thermal quenching with increasing blue LD power density for solid‐state lighting application 11,12 …”