InGaN Blue Chip Research Articles

The Near-infrared luminescence properties and applications of Ca3Lu2Ge3O12:Cr3+ phosphor

The near-infrared (NIR) phosphor-converted LEDs have more merits such as small size, long life and environmental protection to apply in security monitoring, spectrum analysis and biological identification fields. It is necessary to develop high performance NIR luminescent materials matching the commercial blue InGaN chip. This paper reports a broadband emission near-infrared Ca3Lu2Ge3O12:Cr3+ phosphor. Upon 468 nm excitation, the phosphor demonstrates broadband NIR emission centered at ∼793 nm with a large full width at half maximum of ∼130 nm（ΔE=0.258eV). The Cr3+ doped Ca3Lu2Ge3O12 phosphor exhibits good temperature characteristics. The pc-LED device using Ca3Lu2Ge3O12:Cr3+ phosphor excited by a 460 nm commercial blue light chip shows a strong broad NIR emission with output power (38.8 mW at 320 mA). The Cr3+ doped Ca3Lu2Ge3O12 phosphor merged into pc-LED device may be applied in the near-infrared fields.

High stability in color chromaticity of warm White emitting Diode with Dual-Hue SrSi2O2N2:Eu2+,Yb2+ Oxynitridosilicate Phosphorus

<span>In this study, we analyzed and developed a phosphor with a nitridiosilicate based and emitting color changing from green to orange to apply to our white-light-emitting diodes (WLEDs). Eu<sup>2+</sup> and Yb<sup>2+</sup> trap sites of two-doped SrSi<sub>2</sub>O<sub>2</sub>N<sub>2</sub>:Eu<sup>2+</sup>,Yb<sup>2+</sup> (SrYb) nitridosilicate emit a wide emission in the region between green and orange. Through calculating the decompose time of the green-emission power donor, we could determine the converted energy between the active ions. Furthermore, we also analyzed the impact of co-doping with varied active ion ratios on the photoluminescence (PL) characteristics. As the concentration of Yb<sup>2+</sup> increases, the red emission dominates the green. This was because the obtained phoshor's emission depended on the activator ion components. To generate white light, a combination of the acquired phosphor and the InGaN blue LED chip with a 450 nm wavelength was used. With only two steps, we could detect the hue balance management. Firstly, by modifying the Eu<sup>2+</sup> and Yb<sup>2+</sup> concentration, we can conduct a green-to-orange proportion optimization. Following that, the commission onillumination (CIE) coordinates were transformed to [0.4071; 0.3789] from the original position, which was [0.2805; 0.2014] by enhancing the phosphor powder amount. An environment which has a CRI of around 89 is the optimum condition for conducting white light.</span>

Enhancement of the lighting quality for white light-emitting diodes with CaSc2O4:Ce3+ phosphor

<span>For the task of realizing greater progress for the light output in white light-emitting diodes (WLEDs), t</span><span lang="EN-GB">his study focuses on the luminescence temperature subordination feature of CaSc<sub>2</sub>O<sub>4</sub>:Ce<sup>3+</sup> phosphor (abbreviated to CaS for this study). Some other aspects of the phosphor were also included in this piece of paper: Huang-Rhys coupling factor, Stokes shift, triggering power, abatement temperature and especially, abatement behavior in CaSc<sub>2</sub>O<sub>4</sub>:Ce<sup>3+</sup>. Creating the bluish-green LEDs by the combination of blue InGaN chip and CaSc<sub>2</sub>O<sub>4</sub>:Ce<sup>3+</sup> is the primary purpose. CaSc<sub>2</sub>O<sub>4</sub>:Ce<sup>3+</sup> appears to be a decent green phosphor that can be used in WLEDs made of blue InGaN chip. </span><span>Production tasks may be based on our investigation for the task of making desirable WLED devices that meet the production demands.</span>

High-efficiency green and red phosphors enable a broader hue-gamut light-emitting diode backlight for brighter displays

<p><span><span>In this article, </span></span>we suggest combining a blue InGaN chip with strait-band green <span><span>(β-sialon:Eu<sup>2+</sup>), red (K<sub>2</sub>SiF<sub>6</sub>:Mn<sup>4+</sup>) </span></span>phosphors to create WLED devices with a wide hue range and high effectiveness that may be utilized in LCD backlighting. The highest radiation wavelength of a gas-pressure sinted<span><span><br /></span></span><span>β-sialon:Eu<sup>2+ </sup></span>is 535 nm, the full width at half maximum (FWHM) is 54 nm, and the outside quantum performance is 54.0% lower than the 450 nm stimulation. We created K<sub>2</sub>SiF<sub>6</sub>:Mn<sup>4+</sup> in two steps. The phosphor possesses a sharp line radiation spectrum accompanied by the most intense maximum point under 631 nm, an FWHM reaching roughly 3 nm, as well as an exterior quantum effectiveness of 54.5%. When computed at 120 mA, the manufactured three-range wLEDs had an illuminating performance of 91–96 lm/W and a large color temperature of 11,184–13,769 K (i.e., 7,828–8,611 K in LCD screens). The hue range represented by the CIE 1931 and CIE 1976 hue gaps is 85.5-85.9% and 94.3-96.2% of the NTSC requirement, respectively. The optic characteristics outperform those of phosphor-transformed wLED backlights utilizing broad-range green or red phosphors, indicating the two strait-range phosphors studied are the best luminous substances for producing brighter and livelier screens.</p>

Effect of perovskite composition regulation on its crystallization in SiO2–Al2O3–Li2CO3–AlF3–LiF glass system

The green light-emitting aluminosilicate glass with CsPbBr3 quantum dots (QDs) is prepared by the melt-quenching and heat-treatment method. The effect of perovskite composition modulation on the crystallization of CsPbBr3 QDs in glass matrix is discussed in detail. By optimizing the perovskite composition in the fluorosilicate SiO2–Al2O3–Li2CO3–AlF3–LiF glass system, the photoluminescence quantum yield (PLQY) of QDs glass under 365 nm excitation reaches 26.51%. The obtained CsPbBr3 QD glass shows outstanding uniformity, thermal stability and water resistance. White light-emitting diode (WLED) fabricated by using the green QDs glass powder and red nitride commercial phosphor with blue InGaN chip displays luminous efficiency of 24.68 lm/W with CIE coordinates of (0.3361, 0.3300) and correlated color temperature of 5322 K at 10 mA.

Interstitial Li+ Occupancy Enabling Radiative/Nonradiative Transition Control toward Highly Efficient Cr3+-Based Near-Infrared Luminescence.

Highly efficient and stable broadband near-infrared (NIR) emission phosphors are crucial for the construction of next-generation smart lighting sources; however, the discovery of target phosphors remains a great challenge. Benefiting from the interstitial Li+ occupancy-induced relatively large distorted octahedral environment for Cr3+ and suppressed nonradiative relaxation of the emission centers, an NIR emission fluoride phosphor Na3GaF6:Cr3+,Li+ peaking at 758 nm with a high internal quantum efficiency of 95.8% and an external quantum efficiency of 38.3% is demonstrated. Moreover, it exhibits a good thermal stability (84.9%@150 °C of the integrated emission intensity at 25 °C) and excellent moisture resistance as well. A high-power light-emitting diode (LED) with a record watt-level NIR output (974.12 mW) and a photoelectric conversion efficiency of 20.9% is demonstrated by combining Na3GaF6:Cr3+,Li+ and a blue InGaN chip, and a special information encryption/decryption technology suitable for rapid and long-distance identification of machines is further presented based on this device. This study not only advances the development of efficient NIR emission phosphors for broadband NIR LEDs but also for NIR-related emerging applications and devices.

Stable and efficient luminescence of Cs4PbBr6-xIx PQDs glass: a potential material for wide color gamut display.

Zero-dimensional Cs4PbBr6-xIx perovskite quantum dots (PQDs) glass is successfully prepared via a melt quenching method, which provides infinite possibilities for achieving the whole family of zero-dimensional PQDs glass. The test results demonstrate excellent thermal stability and high photoluminescence quantum yields (PLQYs) of Cs4PbBr6-xIx PQDs glass (up to 50%). Finally, the combination of Cs4PbBr6-xIx PQDs glass with an InGaN blue chip is used to fabricate white light-emitting diodes (WLED), which show good color stability at a large operating current, and the color gamut area reaches 137% of NTSC. The above results indicate that zero-dimensional Cs4PbBr6-xIx PQDs glass materials have a broad application prospect in the display lighting field.

A garnet-structured (Y, Ca)3(Al, Mg)2(Al, Si)3O12:Ce3+ phosphor-in-glass engineering for use in high color rendering white LEDs

White light emitting diodes (LEDs) suffer from two most common drawbacks: the deficiency of the red component and the poor thermal stability of silicone. Ce3+-doped garnet phosphors with tailor-made luminescence properties can be achieved by variations in {A}, {B}, and {C} cation sites. Herein, a simultaneous ion co-substitution design strategy has been adopted to synthesize a series of (Y, Ca)3(Al, Mg)2(Al, Si)3O12 garnet phosphors and corresponding phosphor-in-glass (PiG) films. The co-substitution is finely restricted to the assigned sites. The emission peak is shifted from 529 to 565 nm, which is beneficial to obtain low color temperatures and high color rendering using a single phosphor for white LEDs. By employing the as-synthesized phosphor, the corresponding PiG films were fabricated by the low temperature co-sintering technology using the SiO2–B2O3–ZnO–Na2O glass system characterized with excellent thermal stability and moisture resistance. The morphological and elemental analyses demonstrated that the as-made phosphor powders were uniformly distributed in the glass host without any interfacial reactions. Finally, modular white LEDs with a high color rendering (Ra = 82.7) is achieved through the as-synthesized PiG film on an InGaN blue chip. This study may open up a facile approach to obtain high quality luminescence based on the mono-luminescence center, avoiding excitation energy wastage and low quantum efficiency aroused by multi-luminescence centers or color compensation phosphors in glass.

Synthesis and optical properties of a new double-perovskite Rb2KInF6:Mn4+ red phosphor used for blue LED pumped white lighting

High-efficiency narrow-band red phosphor plays a profound part in stimulating illumination quality for white light-emitting diodes (WLEDs). In this work, a series of novel double-perovskite Rb2KInF6:Mn4+ red phosphors was successfully prepared by using a facile co-precipitation technique. The crystallization, particle morphology, photoluminescence properties, and thermal quench behavior of the as-synthesized powder samples were investigated systematically. During the illumination with blue (λmax = 468 nm) and ultraviolet light (λmax = 370 nm), the prepared Rb2KInF6:Mn4+ phosphors emited a series of narrowband red signals in the range 590–660 nm with strong zero-phonon line (ZPL) emission. Meanwhile, the optimum Mn4+ concentration of at the 2Eg→4A2g transitions was also studied. Moreover, the fluorescence decay lifetimes of the prepared Rb2KInF6:Mn4+ products were milliseconds. Finally, by coating Rb2KInF6:Mn4+ with commercially yellow Y3Al5O12:Ce3+ (YAG:Ce3+) phosphors on the commercially available InGaN blue chip, the intense warm white light with suitable correlated color temperature (CCT, 3491 K) and high color-rendering index (Ra, 85.1) can be manufactured at a driving current of 20 mA. All of these consequences point out that the novel double-perovskite red-emitting Rb2KInF6:Mn4+ phosphors are promising in the perspective of WLEDs applications.

Enhancement of the luminescent thermal stability and water resistance of K2TiF6:Mn4+ by organic inorganic hybrid matrix and surface passivation

Due to their attractive luminescent properties, Mn4+-activated fluoride red-emitting phosphors are significant for improving correlated color temperature (CCT) and color rendering index (Ra) of white light-emitting diodes (WLEDs). However, the inherent poor moisture resistance of these phosphors limits their further application in WLEDs. Herein, KTF:TEAH+,Mn4+-P (KTF:TEAH+,Mn4+ = K2TiF6:0.10(C2H5)3NH+,0.04Mn4+, P = passivation with citric acid solution) red emitting phosphor with good water resistance, high luminous intensity and good luminescent thermal stability was generated by combining ion exchange and surface passivation method. The experimental results show that: (a) Emission intensities of samples are improved by using an organic-inorganic hybrid matrix and surface passivation; (b) Water resistances of samples are greatly increased by surface passivation; (c) Negative thermal quenching (NTQ) effect of the samples are enhanced by using an organic-inorganic hybrid matrix and surface passivation. The reason for improvement of water resistance is assigned to the formation of a Mn4+ -rare protective layer on the surface of the sample after surface passivation. Furthermore, the mechanism of the strong NTQ effect is attributed to the increase of electron traps by using an organic-inorganic hybrid matrix and surface passivation. A WLED prototype capable of emitting warm white light (luminous efficiency = 108.6 lm/W, CCT = 3725 K, Ra = 88.4) was assembled by coating a mixture of KTF:TEAH+,Mn4+-P, epoxy resin and YAG:Ce3+ on a blue InGaN chip. These excellent properties indicate that the KTF:TEAH+,Mn4+-P has important application value in blue-excited WLEDs.

Application of green-emitting Sr<sub>3</sub>WO<sub>6</sub>:U phosphor to enhance lumen efficiency of WLEDs

The article demonstrates a sample of spectrum in the phosphor-covered WLED (abbreviated as p-WLED) containing one blue chip, one red chip along with phosphors of green and yellow colors. We acquired the p-WLEDs’ ideal spectrum in the CCTs, which is short for correlated color temperature range from 2700 K to 6500 K using a nonlinear program in order to optimize the radiation’s lumen efficiency (LER) when the R9 strong red's color rendering indexes (CRIs) and special CRIs exceed 98. From the outcomes of the recreation, p-WLEDs containing an InGaN blue chip with 450 nm wavelength, an AlGaInP red chip with 634 nm wavelength, along with green and yellow silicate phosphors with the value of 507 and 580 nm wavelength correspondingly; can produce white lights with CRI values of around 98 and particular CRI values of R9 for intense reds above 98. For saturated red, yellow, green, and blue colors, the average values of the particular CRIs R9 through R12 exceed 95. In CCT values of 2700 K to 6500 K, the R13 value in female figures is around 100, with LER values reaching 296 lm/W.

High Water Resistance and Luminescent Thermal Stability of LiyNa(2-y)SiF6: Mn4+ Red-Emitting Phosphor Induced by Codoping of Li.

Mn4+-doped fluoride phosphors are efficient narrowband red-emitting phosphors for white light-emitting diodes (WLEDs) and backlight displays. However, erosion by moisture is the main obstacle that limits their application. In this work, LNSF:Mn4+ (Li0.06Na1.94Si0.94Mn0.06F6) with high quantum yield (QY), luminescent thermal stability, and waterproofness was synthesized using the H2O2-free reaction method at room temperature. Compared to NSF:Mn4+(Na2Mn0.06Si0.94F6), the QY value, luminescence thermal stability, and water resistance of LNSF:Mn4+ are obviously improved by codoping of Li+ because of the formation of charge-carrier transfer (CT) and rare-Mn4+ layer induced by codoping of Li+. The former produces the negative thermal quenching (NTQ) effect, which results in the improvement of the luminescent thermal stability. The latter can inhibit the hydrolysis of Mn4+ on the surface of the sample, which leads to the enhancement of waterproofness. The formation mechanism of the rare-Mn4+ layer is discussed. A prototype WLED emitting the ideal warm white light (CCT = 3173 K, Ra = 90.4) was assembled by coating a mixture of LNSF:Mn4+, yellow emitting phosphor (YAG:Ce3+), and epoxy resin on the blue light InGaN chip, indicating that the performance of the WLED can be improved by using LNSF:Mn4+.

Luminescence properties of Cr3+-doped near-infrared emissive fluoroyttrates for light-emitting diodes.

In this work, a series of Cr3+-doped A2NaYF6 (denoted as ANYF:Cr; A = K, Rb, and Cs) fluoroyttrate double-perovskites with broad blue excitation and near-infrared (NIR) emission bands were prepared using a high-temperature solid-state reaction method. The physicochemical and spectroscopic properties of the as-prepared products, including crystal structure, bandgap, morphology, luminescence behaviour and optical performance, were studied in detail. The results show that the Cr3+ activators undergo a decreasing crystal field in ANYF in the direction from K to Cs, yielding a red shift of the emission peak position from 758 to 786 nm, whilst the full-width-at-half-maximum (FWHM) expands from 98 to 104 nm. By virtue of the broadband NIR emission, clear structural images of the tangerine section, mini LED flashlight and circuit board were obtained by merging the optimal RNYF:Cr phosphor on a blue InGaN chip, implying its potential use in light-emitting diodes for non-destructive testing.

Achieving a tunable and ultra-broadband near-infrared emission in the Ga2-2xZnxGexO3:Cr3+ phosphor.

Near-infrared (NIR) spectroscopy (700-1100 nm) based on a phosphor-converted light-emitting diode (pc-LED) has multi-functional applications in bio-imaging, night-vision, and food quality analysis, simulating the development of efficient and ultra-broadband NIR phosphors. Herein, a series of tunable and ultra-broadband NIR phosphor Ga2-2xZnxGexO3:Cr3+ was successfully produced by a [Zn2+-Ge4+] unit co-substituting a [Ga3+-Ga3+] unit in Ga2O3:Cr3+. With the increasing amount of [Zn2+-Ge4+] incorporation, the emission peak can be tuned from 726 to 808 nm, and the maximum FWHM can be extended from 126 to 190 nm. However, the excitation peak position remained nearly unchanged in the blue light region, enabling this material to perfectly match the InGaN blue LED chip. Although the gradually enhanced electron-lattice coupling and low energy barrier for thermal quenching caused by this co-substitution lead to a decrease in the photoluminescence quantum yield (PLQY) and thermal stability, respectively, the absolute values of these two criteria can be well maintained. Finally, to evaluate the practical applications, prototype NIR pc-LEDs were fabricated using these materials combined with 450 nm LED chips. Under the same conditions, the NIR output power and photoelectronic conversion efficiency of these devices are superior to those fabricated using the well-known ScBO3:Cr3+ phosphor. These results demonstrate that this series of materials with tunable and ultra-broadband NIR emissions has great potential for NIR pc-LED applications.

Photoluminescence enhancement of orange-emitting Ca5(PO4)2SiO4:Sm3+ phosphor through charge compensation of A+ (Li+, Na+ and K+) ions for white light-emitting diodes.

The orange-emitting Ca5-x(PO4)2SiO4:xSm3+ (C5PSO:Sm3+) phosphor was prepared via a simple solid-state method, and the charge compensators A+ (A = Li, Na and K) were codoped into C5PSO:Sm3+ for improving the luminescence performance. The influences ofSm3+doping and Sm3+/A+ codoping on the crystal structure and the luminescence performance of the C5PSO:Sm3+ phosphor were investigated in detail. The X-ray diffraction results exhibited that all the as-prepared samples were assigned to the standard structure Ca5(PO4)2SiO4 possessing the P63/m space group. Upon near-ultraviolet excitation at 401 nm, the characteristic emission peaks of the C5PSO:Sm3+ phosphors are located at 558 nm, 605 nm and 656 nm, respectively, which are derived from the 4G5/2 → 6HJ (J = 5/2, 7/2, and 9/2) electron transitions of Sm3+ ions. Furthermore, a significant luminescence improvement of the C5PSO:Sm3+ phosphor was attained through charge compensation of codoped A+ ions, and the emission intensity is enhanced by 1.79-, 1.45-, and 1.14-fold for K+, Na+, and Li+, respectively. In addition, the actual orange-red LED and w-LED fabricated with the as-prepared C5PSO:Sm3+,K+ phosphor showed excellent optical performance. All the results demonstrated that the C5PSO:Sm3+,K+ orange-emitting phosphor could act as a potential orange-red component in the w-LEDs illumination field.

3D quantum dot-lens fabricated by stereolithographic printing with in-situ UV curing for lighting and displays

3D polymer/quantum dots (QDs) nanocomposite QD-lens is fabricated by stereolithography (SLA) 3D printer with in-situ UV curing system. Various UV-curable polymer precursors are mixed with QDs to investigate their printability and optical performance. 2D QD-thin film and 3D QD-lens are printed and attached to a blue InGaN chip to form a light-emitting diode (LED) device. An air gap between the 3D QD-lens and the chip provides more uniform light emission at different angles and better heat dissipation. Compared with conventional QD-on-chip LED, the 3D QD-lens LED operated at 20 mA has ∼100% enhancement of half-lifetime (T 50 ) in a standard reliability test. The LED T 50 can be further improved 75% by coating the QD-lens with hydrophobic parylene as a gas barrier layer against water and oxygen. By mixing both green- (G-) and red- (R-) QDs in the 3D QD-lens, a white light-emitting 3D QD-lens LED is demonstrated to possess a color gamut of ∼130% NTSC standard.

Enhancement of the luminescent thermal stability and water resistance of K2SiF6:Mn4+,Na+ by double coating of GQDs and K2SiF6

Nowadays, it is still a big challenge to synthesize Mn4+-doped fluoride red phosphors with high water resistance, luminescent intensity and thermal stability simultaneously. Therefore, KSF:M,N@GQDs@KSF (K2SiF6:0.06Mn,0.10Na@GQDs (12 mg/mol)@K2SiF6(0.2 wt), KSF: K2SiF6, GQDS: OH-contained graphene quantum dots) with high luminescent intensity, high luminescent thermal stability and water resistance have been synthesized via a combination of H2O2-free room temperature reaction method, hydrothermal coating method and room temperature surface coating process. Experimental results show that enhancement of negative thermal quenching (NTQ) effect and water resistance can be synergistically induced by double coating of GQDs and KSF. After being immersed in deionized water for 360 min, emission intensities of the KSF:M,N@GQDs and KSF:M,N@GQDs@KSF are decreased from 100% to 70.57% and 91.63%, respectively, indicating that water resistance of the latter is obviously improved by coating of KSF. The improved water resistance is attributed to preventing hydrolysis of [MnF6]2- on sample’s surface by insoluble coating shell of KSF. A prototype WLEDs (white light-emitting diodes) emitted warm white light (CCT = 4546 K and Ra = 91.3, at a driving current of 20 mA) has been assembled by coating mixture of KSF:M,N@GQDs@KSF, yellow emitting phosphor (YAG:Ce3+) and epoxy resin on blue light InGaN chips. The good performances of the WLEDs suggest that the KSF:M,N@GQDs@KSF has potential applications in blue-based warm WLEDs.

(Ce, Gd):YAG-Al2O3 composite ceramics for high-brightness yellow light-emitting diode applications

(Ce,Gd):YAG-Al2O3 composite ceramics were prepared for high-brightness yellow LED (565−590 nm) applications. Phase fraction, microstructure, thermal quenching effect, and luminescent properties of composite ceramics with varying compositions were studied in detail. Collaborating composite ceramics with InGaN blue chips, the relationship between thermal conductivity, temperature rise during LED-driven phosphor conversion, and steady-state luminous efficiency were elucidated. As the proportion of Al2O3 increases from 0 to 40 wt%, the steady-state luminous efficiency of yellow LED is enhanced from 100.88–109.49 lm W−1, benefiting from the increased thermal stability and reduced operating temperature of ceramics (from 141.1–132.2 °C). Additionally, scattering behavior and extraction efficiency of composite ceramics with different thicknesses were investigated.

Stable Dy-doped CsPbBr3 quantum dot glass with enhanced optical performance

Using conventional melt-quenching and heat treatment method, Dy3+ -doped CsPbBr3 perovskite quantum dots were successfully prepared in a borosilicate glass matrix. Under suitable Dy2O3 doping conditions, Dy3+ ions can effectively promote the nucleation and growth of CsPbBr3 quantum dots in the glass matrix, and the PLQYs increased from 35.9 to 62.5%. Using the CsPbBr3: xDy3+ glass powder and commercial K2SiF6: Mn4+ red phosphor to coat blue InGaN chips can prepare white LEDs. Driven by a current of 40 mA, the white LED of the CIE coordinates is (0.2881, 0.3001) and have a wide color gamut about 126.3% NTSC value. Therefore, CsPbBr3 perovskite quantum dot glass doped with Dy3+ has shown great potential in light-emitting devices.

Cost-Effective Strategy for the Synthesis of Air-Stable CH3NH3PbX3 (X = Cl, Br, and I) Quantum Dots with Bright Emission.

Lead halide perovskite quantum dots (QDs) are known as prospective optoelectronic device materials because of their excellent luminescence, extraordinary photoelectric performance, and specific octahedron framework. Herein, we report a cost-effective approach for synthesizing highly stable CH3NH3PbBr3 QDs in low-polarity binary solvents without nitrogen protection. The CH3NH3PbBr3 QDs are tunable from 1.2 to 4.2 nm by adjusting the proportion of oleic acid and oleylamine as capping ligands. The photoluminescence quantum yield of CH3NH3PbBr3 QDs can reach 87.4%. The fluorescence can maintain over 80% of its earliest emission intensity under the atmosphere after 5 days, which is much better than that (∼10%) of QDs with ligand-assisted reprecipitation. The possible reaction mechanism of preparing CH3NH3PbBr3 QDs was also addressed. Notably, such a strategy can be applied extensively in the preparation of other lead halide perovskite QDs. Furthermore, the as-prepared thick PMMA-coated CH3NH3PbBr3 QDs were further conjoined with a red luminescence powder on a blue InGaN chip to obtain a powerful efficiency (45.4 lm W-1) warm white light-emitting diode.