Ca1−xLixAl1−xSi1+xN3:Eu2+ solid solutions as broadband, color-tunable and thermally robust red phosphors for superior color rendition white light-emitting diodes

Abstract

Color rendition, luminous efficacy and reliability are three key technical parameters for white light-emitting diodes (wLEDs) that are dominantly determined by down-conversion phosphors. However, there is usually an inevitable trade-off between color rendition and luminescence efficacy because the spectrum of red phosphor (that is, spectral broadness and position) cannot satisfy them simultaneously. In this work, we report a very promising red phosphor that can minimize the aforementioned trade-off via structure and band-gap engineering, achieved by introducing isostructural LiSi2N3 into CaAlSiN3:Eu2+. The solid solution phosphors show both substantial spectra broadening (88→117 nm) and blueshift (652→642 nm), along with a significant improvement in thermal quenching (only a 6% reduction at 150 °C), which are strongly associated with electronic and crystal structure evolutions. The broadband and robust red phosphor thus enables fabrication of super-high color rendering wLEDs (Ra=95 and R9=96) concurrently with the maintenance of a high-luminous efficacy (101 lm W−1), validating its superiority in high-performance solid state lightings over currently used red phosphors.

Controllable synthesis of glass ceramics containing YF3:Eu3+ nanocrystals: Well‐preserved Eu and prolonged lifetime

“…With an increase in YF 3 :Eu 3+ content, the emission intensity rises firstly and reaches its maximum when the concentration is 3 wt%, followed with a slight decrease. This decrease was a consequence of the increased non‐radiative transition from thermal quenching caused by the increased sintering temperature . Besides, the transparency declined gradually with the increased content of YF 3 :Eu 3+ NCs, which also affected the emission intensity to a certain extent.…”

The Enhanced Red Emission and Improved Thermal Stability of CaAlSiN3:Eu2+ Phosphors by Using Nano-EuB6 as Raw Material

“…The traditional way used to obtain white light is combing blue InGaN LEDs chip with the yellow phosphor Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ). However, using a single yellow phosphor leads to low color rendering index (Ra < 80) due to the insufficient red component in the spectra, making them unsuitable for high-quality “warmer” white lighting [4,5,6,7]. Therefore, a red emitting phosphor is thus essentially needed to enhance the red spectral part to achieve much higher color rendering indices.…”

Facile synthesis of the desired red phosphor Li2Ca2Mg2Si2N6:Eu2+ for high CRI white LEDs and plant growth LED device

“…The desirable red emission spectra of Li 2 Ca 2 Mg 2 Si 2 N 6 :1.0%Eu 2+ is an attractive candidate for high CRI white LEDs. To demonstrate the potential application of Li 2 Ca 2 Mg 2 Si 2 N 6 :1.0%Eu 2+ , the white LEDs (2) device was fabricated by combining the commercial yellow phosphor (Y 3 Al 5 O 12 :Ce 3+ ) with the as-prepared red phosphor on a blue LED chip. And the same time, a commercial white LEDs (1) was also fabricated using a blue LED chip combined with commercial yellow Y 3 Al 5 O 12 :Ce 3+ phosphor for comparison.…”

“…To pursue high luminous efficacy and reduce energy consumption caused by low eye sensitivity in the infrared region, red phosphors with suitable peak wavelength and narrow band are urgently needed for high color rendering index (CRI) white LEDs. 1,2 There is a trade-off between luminous efficacy and high CRI in all types of white LEDs, which means that the improvement in one usually brings about the reduction of the other. The emission peak should be at ~630 nm with relatively narrow band for the optimum balance.…”