Compatibility of Photoluminescence Properties in ScPO4:Eu3+, Tb3+ Phosphor for White Light Emitting Diodes

2021 ◽  
Vol 21 (12) ◽  
pp. 5890-5895
Author(s):  
Jian Zhou ◽  
Jian-Wen Zhao ◽  
Si-Li Ren ◽  
Jun Dong
Keyword(s):  
The Body ◽  
Color Temperature ◽  
White Led ◽  
Photoluminescence Properties ◽  
Light Emitting ◽  
Co Doping ◽  
Emission Color ◽  
Single Matrix ◽  
White Light Emitting Diodes ◽  
Color Rendering

ScPO4:Eu3+, Tb3+ phosphors with tuned emission color were prepared through high temperature solid-state reaction. The structure, morphology and photoluminescence properties of the title samples were collected by XRD, SEM and fluorescence spectrophotometer, respectively. Co-doping Eu3+ and Tb3+ in ScPO4 does not change the body-centered tetragonal structure of the host. And the morphology remains essentially unchanged except for slight agglomeration. Changing the ratio of Tb3+/Eu3+, the tuned emission can be achieved, the color could be adjusted from green through yellow to orange-red. The ScPO4:0.03Tb3+, 0.03Eu3+ phosphor with high thermal stability as the single matrix phosphor can be suitable for the NUV-pumped white LED. The white LED with a color rendering index of 86.5 and a correlated color temperature of 3470 K has been generated by packaging BAM:Eu2+ with ScPO4:0.03Tb3+, 0.03Eu3+ on an NUV-InGaN chip.

scholarly journals Light Output, Thermal Properties, and Reliability of Using Glass Phosphors in WLED Packages

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 239
Author(s):  
Chin-Chuan Huang ◽  
Tsung-Han Weng ◽  
Chun-Liang Lin ◽  
Yan-Kuin Su
Keyword(s):  
Thermal Properties ◽  
Yttrium Aluminum Garnet ◽  
Saturated Vapor ◽  
Light Output ◽  
Junction Temperature ◽  
Color Temperature ◽  
Light Emitting ◽  
Chromaticity Coordinate ◽  
White Light Emitting Diodes ◽  
Color Rendering

White-light-emitting diodes (WLED) based on yttrium aluminum garnet (YAG) phosphors sintered with glass (PiG) and with silicone (PiS) are compared in terms of their light properties, temperature properties and reliability.The complete YAG phosphor was doped with an encapsulant traditional WLED (PiS WLED), and the WLED was covered with PiG (PiG WLED). PiG was made by sintering glass powder and YAG phosphor at the ratio of 87:13 (%), and the correlated color temperature (CCT) was 5564 K. The CCT of the PiG WLED with the YAG doping concentration of 8.5 wt.% approximated 5649 K. The initial light output of the PiG WLED was 6.4% lower than that of the PiS WLED. Under 1008 h and 350 mA aging, PiG WLED and PiS WLED’ light output, CCT and color rendering index variation rates were all within 1%. In the saturated vapor-pressure test, no sample exhibited red ink infiltration, light nor peeling between the encapsulant and the lead-frame. Compared with that of the PiS WLED, the junction temperature of the PiG WLED reduced from 88.4 °C to 81.3 °C. Thermal resistance dropped from 37.4 °C/W to 35.6 °C/W. The PiG WLED presented a better CIE (Commission Internationale de l’Eclairage) 1931 chromaticity coordinate (x,y) concentration and thermal properties than the PiS WLED.

An efficient rare-earth free deep red emitting phosphor for improving the color rendering of white light-emitting diodes

2017 ◽  
Vol 5 (11) ◽  
pp. 2927-2935 ◽  
Author(s):  
Sisi Liang ◽  
Mengmeng Shang ◽  
Hongzhou Lian ◽  
Kai Li ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Rare Earth ◽  
White Light ◽  
Light Emitting Diodes ◽  
Photoluminescence Properties ◽  
Red Emission ◽  
Light Emitting ◽  
White Light Emitting Diodes ◽  
Color Rendering ◽  
Red Emitting Phosphor

The Mn4+doped Mg14Ge5O24phosphor produces deep red emission, and the structure, photoluminescence properties, thermal stability and the performance of fabricated WLED are all investigated.

Luminescence properties of single-phase color-tunable Li4SrCa(Si2O4N8/3):Eu2+ phosphor for white light-emitting diodes

RSC Advances ◽  
2016 ◽  
Vol 6 (45) ◽  
pp. 38731-38740 ◽  
Author(s):  
Chenxia Li ◽  
Jian Dai ◽  
Hua Yu ◽  
Degang Deng ◽  
Jun Huang ◽  
...  
Keyword(s):  
White Light ◽  
Single Phase ◽  
Light Emitting Diodes ◽  
Color Temperature ◽  
White Led ◽  
Light Emitting ◽  
Color Coordinates ◽  
Uv Led ◽  
Color Tunable ◽  
White Light Emitting Diodes

A white LED consisting of a LSCSN:0.03Eu2+ phosphor and a 375 nm UV LED chip had CIE color coordinates of (0.3568, 0.3111) and achieved a Ra of 82.5 around the correlated color temperature of 3318 K.

scholarly journals Facile Preparation of Stable Solid-State Carbon Quantum Dots with Multi-Peak Emission

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 303 ◽  
Author(s):  
Yanning Zheng ◽  
Jingxia Zheng ◽  
Junli Wang ◽  
Yongzhen Yang ◽  
Taiping Lu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Solid State ◽  
Carbon Quantum Dots ◽  
Color Temperature ◽  
Light Emitting ◽  
One Step ◽  
White Light Emitting Diodes ◽  
Color Rendering ◽  
Peak Emission

Aggregation-caused quenching (ACQ) effect, known as the main cause to restrain solid-state luminescence of carbon quantum dots (CQDs), hinders further application of CQDs in white light-emitting diodes (WLED). Here, a complex of CQDs and phthalimide crystals (CQDs/PC) was prepared through a one-step solvothermal method. CQDs/PC prevented CQDs from touching directly by embedding the CQDs in phthalimide crystal matrix in situ, which effectively reduced the ACQ effect. Furthermore, CQDs/PC exhibited multi-peak fluorescence spectra that span the green, yellow and orange spectral regions. Finally, a WLED fabricated based on CQDs/PC achieved a color-rendering index of 82 and a correlated color temperature of 5430 K. This work provides a quick and effective strategy to apply CQDs to WLED.

Room-temperature synthesis, controllable morphology and optical characteristics of narrow-band red phosphor K2LiGaF6:Mn4+

CrystEngComm ◽  
2018 ◽  
Vol 20 (15) ◽  
pp. 2183-2192 ◽  
Author(s):  
Haiming Cheng ◽  
Yan Song ◽  
Feng Hong ◽  
Guixia Liu ◽  
Dan Li ◽  
...  
Keyword(s):  
Room Temperature ◽  
Narrow Band ◽  
Color Temperature ◽  
Temperature Synthesis ◽  
Red Phosphor ◽  
Light Emitting ◽  
Yellow Phosphor ◽  
Red Phosphors ◽  
White Light Emitting Diodes ◽  
Color Rendering

The white light-emitting diodes fabricated by mixing GaN chips with yellow phosphor (Y3Al5O12:Ce3+) and red phosphors (K2LiGaF6:Mn4+) exhibit good performance with lower color temperature and higher color rendering index.

Packaging of Phosphor Based High Power White LEDs: Effects of Phosphor Concentration and Packaging Configuration

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
Yuan-Chang Lin ◽  
Jiun Pyng You ◽  
Nguyen T. Tran ◽  
Yongzhi He ◽  
Frank G. Shi
Keyword(s):  
Optical Power ◽  
Luminous Efficiency ◽  
Color Temperature ◽  
Light Emitting ◽  
White Leds ◽  
Chromaticity Coordinate ◽  
Air Interface ◽  
Output Only ◽  
White Light Emitting Diodes ◽  
Color Rendering

Two types of packaged white light emitting diodes in which one has a flat-top (FT) emitting surface and the other is a flat-top-with-lens (FTWL) type are fabricated by using the same leadframe and investigated on their optical properties, such as optical power, luminous efficiency, correlated color temperature (CCT), chromaticity coordinate, and color-rendering index (CRI), as a function of phosphor concentration in silicone encapsulant. It is found out that the optical power, CRI, and CCT decrease steadily as the phosphor ratio increases, while the luminous efficiency increases up to a level and then drops after a certain value of the phosphor ratio for both types of packages. Due to the totally internal reflection (TIR) at the encapsulant-air interface, the FT package shows a 10∼11% power (in mW) reduction compared with the FTWL package at the same phosphor concentration. However, it is demonstrated that the FT package provides a more efficient way of utilizing phosphor than the FTWL package based on the same targeted chromaticity coordinates due to the TIR effect inside, resulting in a reduced phosphor usage with a lumen output only about 3% lower than that of the FTWL package.

scholarly journals An Emerging White LED Technology and associated Thermal Issues – A Review

2019 ◽  
pp. 106-120
Keyword(s):  
High Efficiency ◽  
Heat Sinks ◽  
Light Sources ◽  
White Led ◽  
Color Gamut ◽  
Light Emitting ◽  
White Leds ◽  
Long Life ◽  
White Light Emitting Diodes ◽  
Color Rendering

White light emitting diodes (white-LEDs) are the promising light sources of new lighting technology due to their high efficiency, energy saving, long life and environmentally friendly. In this review, different techniques proposed for the development of white-LEDs have been discussed in terms of their performance efficiency and potential usage. The Phosphor based white-LEDs are widely used LEDs, as compared to RGB based white-LEDs, due to their luminous efficacy, service life, display color gamut and the color rendering. Furthermore, thermal issues related to high power white-LEDs have been discussed as it greatly impacts the performance efficiency. To resolve thermal issues, heat sinks having high thermal conductivity are most widely used among others.

scholarly journals COLOR AND SPECTRAL CHARACTERISTICS OF WHITE LIGHT EMITTING DIODES AND THEIR VARIATION DURING AGING

Doklady BGUIR ◽  
2019 ◽  
pp. 39-45
Author(s):  
A. L. Gurkii ◽  
M. V. Masheda
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Spectral Characteristics ◽  
Color Temperature ◽  
Luminescence Spectra ◽  
White Led ◽  
Green Band ◽  
Blue Band ◽  
Light Emitting ◽  
White Light Emitting Diodes

The relation between numerical values of photometric characteristics (total luminous flux TLF, correlated color temperature CCT, color rendering index CRI) of white light emitting diodes (LED) and the variation of the spectral shape of their radiation during aging has been investigated. All the measurements were made on internationally adopted test methods, taking into account environmental conditions, electrical parameters and evaluated measurement uncertainty. Every piece of test and measurement equipment has actual verification or calibration with traceability to national and international references. It was demonstrated that in the luminescence spectra consisting of the “blue” band around 450 nm originating from the semiconductor heterostructure, and the broad “yellow” band from luminophor, the last band is nonelementary and consists of at least two bands: the “green” one around 530 nm and the “orange” one around 580 nm. The most unstable “green” band has the highest impact on photometric characteristics. As a consequence, further investigation should be performed on how instability of elementary bands and its quantity will link not only with photometric characteristics, but with production conditions and material properties of LED heterostructure and luminophor itself. In particular, for improvement of the color stability of white LED, the parameters of luminophor forming the “green” band should be stabilized. А unified method for accelerated testing of LED products and method for long-time lifetime prediction shall be developed, taking into account not only depreciation of TLF, but also shift of other photometric and spectral characteristics of white LED.

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