Selecting the optimal synthesis parameters of InP/Cd[x]Zn[1-x]Se quantum dots when combined with different broad band phosphors to optimize color rendering and efficiency of a remote phosphor white LED

White light-emitting diodes (WLEDs) composed of blue LED chip, yellow phosphor, and red quantum dots (QDs) are considered as a potential alternative for next-generation artificial light source with their high luminous efficiency (LE) and color-rendering index (CRI). While, QDs’ poor temperature stability and the incompatibility of QDs/silicone severely hinder the wide utilization of QDs-WLEDs. To relieve this, here we proposed a separated QSNs/phosphor structure, which composed of a QSNs-on-chip layer with a yellow phosphor layer above. A silica shell was coated onto the QDs surface to solve the compatibility problem between QDs and silicone. With CRI > 92 and R9 > 90, the newly proposed QDs@silica nanoparticles (QSNs) based WLEDs present 16.7 % higher LE and lower QDs working temperature over conventional mixed type WLEDs. The reduction of QDs’ temperature can reach 11.5 °C, 21.3 °C and 30.3 °C at driving current of 80 mA, 200 mA and 300 mA, respectively.

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High color rendering index white LEDs fabricated using InP/ZnS green-emitting quantum dots and InP/ZnSe/ZnS red-emitting quantum dots

2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) ◽

10.1109/sslchinaifws49075.2019.9019770 ◽

2019 ◽

Author(s):

Doudou Zhang ◽

Yuxian Yan ◽

Fan Cao ◽

Gongli Lin ◽

Xuyong Yang ◽

...

Keyword(s):

Quantum Dots ◽

White Leds ◽

Color Rendering Index ◽

Color Rendering

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(Y,Gd)BO3:Eu red phosphor for dual-layer phosphor structure to enhance the optical performance of white light-emitting diodes

Bulletin of Electrical Engineering and Informatics ◽

10.11591/eei.v10i4.2909 ◽

2021 ◽

Vol 10 (4) ◽

pp. 1930-1935

Author(s):

Phan Xuan Le ◽

Le Hung Tien

Keyword(s):

White Light ◽

Light Emitting Diodes ◽

Red Light ◽

Phosphor Layer ◽

Light Emitting ◽

Conformal Coating ◽

Color Quality ◽

Remote Phosphor ◽

White Light Emitting Diodes ◽

Color Rendering

Among the structures using for fabricating white light-emitting diodes (WLEDs) such as the conformal coating or in-cup geometries, the remote phosphor structure gives the highest luminous efficacy. However, in terms of color quality, its performance is not as good as the others. The red-light compensation has been reported as the effective solution for enhancing the color quality of WLEDs. Hence, this study adopted the idea and applied to the dual-layer phosphor structure. The phosphor used to boost the red color in light formation is (Y,Gd)BO3:Eu particle. The dual-layer remote phosphor structure was simulated with the red (Y,Gd)BO3:Eu phosphor layer above the original yellow phosphor YAG:Ce3+ one. The WLEDs with different correlated color temperatures of 5600 K, 6600 K and 7700K were experimented. Mie-theory and Lambert-Beer law were applied to examine the results. The growth in color rendering index (CRI) and color quality scale (CQS) with the increase of (Y,Gd)BO3:Eu phosphor concentration was observed. Nevertheless, the lumen efficacy would be degraded if the concentration was over a certain number. The information provided in this article is useful for the development of high-power WLED production with greater color quality.

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