scholarly journals Fractional Contributions of Defect-Originated Photoluminescence from CuInS2/ZnS Coreshells for Hybrid White LEDs

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Quinton Rice ◽  
Sangram Raut ◽  
Rahul Chib ◽  
Zygmunt Gryczynski ◽  
Ignacy Gryczynski ◽  
...  
Keyword(s):  
Thermal Quenching ◽  
Defect State ◽  
White Led ◽  
Time Resolved ◽  
Light Emitting ◽  
White Leds ◽  
Slow Decay ◽  
Interface Defect ◽  
Donor Acceptor ◽  
White Light Emitting Diodes

The wide optical tunability and broad spectral distribution of CuInS2/ZnS (CIS/ZnS) coreshells are key elements for developing the hybrid white light emitting diodes where the nanoparticles are stacked on the blue LEDs. TwoCIS/ZnS555 nmandCIS/ZnS665 nmcoreshells are utilized for the hybrid white LED development. The time-resolved spectroscopy ofCIS/ZnS555 nmandCIS/ZnS665 nmreveals the correlation between the fast, intermediate, and slow decay components and the interface-trapped state and shallow- and deep-trapped states, although the fractional amplitudes of photoluminescence (PL) decay components are widely distributed throughout the entire spectra. The temperature-resolved spectroscopy explains that the PL from deep-trapped donor-acceptor (DA) state has relatively large thermal quenching, due to the relative Coulomb interaction of DA pairs, compared to the thermal quenching of PL from interface defect state and shallow-trapped DA state. A good spectral coupling between the blue diode excitation and the PL from CIS/ZnS leads to the realization of hybrid white LEDs.

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.

Design of High Power RGB White Light Emitting Diodes

2013 ◽  
Vol 423-426 ◽  
pp. 2645-2650
Author(s):  
Wei Chen ◽  
Lang Wang ◽  
Lian Qiao Yang ◽  
Jian Hua Zhang
Keyword(s):  
Simulation Method ◽  
Thermal Simulation ◽  
Optimization Approach ◽  
White Led ◽  
Optical Performance ◽  
Light Emitting ◽  
White Leds ◽  
High Efficient ◽  
Volume Method ◽  
White Light Emitting Diodes

In this paper, thermal performance of RGB white LED packages was optimized by thermal simulation using the Finite Volume method. A Monte Carlo photon simulation method was utilized for the analysis of optical performance of LED in quantitative terms. It was found that the distribution of RGB chips has great effect both on the thermal and optical performance of the RGB white LEDs. The tilted angle, material of the reflection cup, and the shape of encapsulant were found to be the key factors which determine the extraction efficiency of LED package. It is demonstrated that the combination of optical and thermal simulation provides a comprehensive optimization approach for a design of high efficient RGB white LED package.

scholarly journals NUV-pumped luminescence of thermally stable samarium-activated alkali metal borophosphate phosphor

2021 ◽  
Author(s):  
Zhenyu Fang ◽  
Dan Yang ◽  
Youkui Zheng ◽  
Jialiang Song ◽  
Tongsheng Yang ◽  
...  
Keyword(s):  
Thermal Quenching ◽  
Particle Morphology ◽  
Color Temperature ◽  
Quenching Mechanism ◽  
Light Emitting ◽  
White Leds ◽  
Near Ultraviolet ◽  
Chromatic Properties ◽  
White Light Emitting Diodes ◽  
Powder Phase

AbstractExploring outstanding rare-earth activated inorganic phosphors with good thermostability has always been a research focus for high-power white light-emitting diodes (LEDs). In this study, we report a Sm3+-activated KNa4B2P3O13 (KNBP) powder phase. Its particle morphology, photoluminescence properties, concentration quenching mechanism, thermal quenching mechanism, and chromatic properties are demonstrated. Upon the near-ultraviolet (NUV) irradiation of 402 nm, the powder phase exhibits orange-red visible luminescence performance, originating from typical 4G5/2→6HJ/2 (J = 5, 7, 9) transitions of Sm3+. Importantly, the photoluminescence performance has good thermostability, low correlated color temperature (CCT), and high color purity (CP), indicating its promising application in the NUV-pumped warm white LEDs.

Growth and Light Properties of Fluorescent SiC for White LEDs

2012 ◽  
Vol 717-720 ◽  
pp. 87-92
Author(s):  
Mikael Syväjärvi ◽  
Rositza Yakimova ◽  
Motoaki Iwaya ◽  
Tetsuya Takeuchi ◽  
Isamu Akasaki ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
White Light ◽  
Energy Savings ◽  
Red Light ◽  
Visible Range ◽  
White Led ◽  
Light Emitting ◽  
Blue Led ◽  
White Leds ◽  
New Type

The LED technology started to developed many years ago with red light emitting diodes. To achieve the blue LED, novel growth technologies and process steps were explored, and made it possible to demonstrate efficient blue LED performance from nitrides. The efficiency was further developed and blue LEDs were commercially introduced in the 1990’s. The white LED became possible by the use of the blue LED and a phosphor that converts a part of the blue light to other colors in the visible range to combine into white light. However, even today there are limitations in the phosphor-based white LED technology, in particular for general lighting, and new solutions should be explored to speed the pace when white LEDs will be able to make substantial energy savings. In this paper we overview gallium nitride materials evolution and growth concepts for LEDs. We describe the fluorescent silicon carbide material prepared by a novel growth technology for a new type of white LED in general lighting with pure white light. This paper introduces an interesting research in fundamental growth and optical properties of light emitting silicon carbide.

Three-dimensional GaN dodecagonal ring structures for highly efficient phosphor-free warm white light-emitting diodes

Nanoscale ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 4686-4695 ◽  
Author(s):  
Young Chul Sim ◽  
Seung-Hyuk Lim ◽  
Yang-Seok Yoo ◽  
Min-Ho Jang ◽  
Sunghan Choi ◽  
...  
Keyword(s):  
White Light ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Three Dimensional ◽  
Light Emitting ◽  
White Leds ◽  
Highly Efficient ◽  
Warm White Light ◽  
Ring Structures ◽  
White Light Emitting Diodes

Multifaceted dodecagonal ring structures emit light of various colours with high efficiency and are demonstrated to be phosphor-free white LEDs.

Novel polygonal structure Mn4+ activated In3+-based Elpasolite-type hexafluorides red phosphor for warm white light-emitting diodes (WLEDs)

2019 ◽  
Vol 48 (4) ◽  
pp. 1376-1385 ◽  
Author(s):  
Feng Hong ◽  
Haiming Cheng ◽  
Chao Song ◽  
Guixia Liu ◽  
Wensheng Yu ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Synthetic Methods ◽  
Red Phosphor ◽  
Light Emitting ◽  
White Leds ◽  
Red Phosphors ◽  
Polygonal Structure ◽  
Warm White Light ◽  
White Light Emitting Diodes

Red phosphors (NH4)2NaInF6:Mn4+ with controllable morphology were synthesized via different synthetic methods, which can be fabricated for warm white LEDs.

Synthesis, structure and luminescence properties of new blue-green-emitting garnet-type Ca3Zr2SiGa2O12:Ce3+ phosphor for near-UV pumped white-LEDs

RSC Advances ◽  
2016 ◽  
Vol 6 (3) ◽  
pp. 2155-2161 ◽  
Author(s):  
Jiyou Zhong ◽  
Weidong Zhuang ◽  
Xianran Xing ◽  
Ronghui Liu ◽  
Yanfeng Li ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diodes ◽  
Luminescence Properties ◽  
Light Emitting ◽  
White Leds ◽  
White Light Emitting Diodes

A new blue-green-emitting garnet-type phosphor Ca3Zr2SiGa2O12:Ce3+ has been explored for n-UV pumped white light-emitting diodes.

scholarly journals Preparation of Bismuth Oxide Photocatalyst and Its Application in White-light LEDs

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yen-Chang Chu ◽  
Gang-Juan Lee ◽  
Chin-Yi Chen ◽  
Shih-Hsin Ma ◽  
Jerry J. Wu ◽  
...  
Keyword(s):  
Bismuth Oxide ◽  
White Light ◽  
Front Surface ◽  
Color Temperature ◽  
Spray Pyrolysis Method ◽  
Light Emitting ◽  
White Leds ◽  
Air Purifier ◽  
Cie Chromaticity ◽  
White Light Emitting Diodes

Bismuth oxide photocatalysts were synthesized and coated on the front surface of phosphor-converted white light-emitting diodes to produce a safe and environmentally benign lighting source. Bismuth oxide photocatalyst powders were synthesized with a spray pyrolysis method at 500°C, 600°C, 700°C, and 800°C. Using the absorption spectrum in the blue and UV regions of the bismuth oxide photocatalysts, the blue light and UV leakage problems of phosphor-converted white LEDs can be significantly reduced. The experimental results showed that bismuth oxide photocatalyst synthesized at 700°C exhibited the most superior spectrum inhibiting ability. The suppressed ratio reached 52.33% in the blue and UV regions from 360 to 420 nm. Related colorimetric parameters and the photocatalyst decomposition ability of fabricated white-light LEDs were tested. The CIE chromaticity coordinates(x,y)were (0.349, 0.393), and the correlated color temperature was 4991 K. In addition, the coating layer of photocatalyst can act as an air purifier and diffuser to reduce glare. A value of66.2±0.60 ppmv of molecular formaldehyde gas can be decomposed in 120 mins.

Eu2+-activated full color orthophosphate phosphors for warm white light-emitting diodes

RSC Advances ◽  
2014 ◽  
Vol 4 (62) ◽  
pp. 33114-33119 ◽  
Author(s):  
Chenglong Zhao ◽  
Zhiguo Xia ◽  
Molin Li
Keyword(s):  
White Light ◽  
Potential Application ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
White Leds ◽  
Full Color ◽  
Warm White Light ◽  
White Light Emitting Diodes

Eu2+-activated full-color versatile orthophosphate phosphors can find potential application in warm white LEDs.

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