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With increasing ecological and environmental concerns, tin (Sn)‐based perovskite light‐emitting diodes (PeLEDs) are competitive candidates for future displays because of their environmental friendliness, excellent photoelectric properties, and low‐cost solution‐processed fabrication. Nonetheless, their electroluminescence (EL) performance still lags behind that of lead (Pb)‐based PeLEDs due to the fast crystallization rate of Sn‐based perovskite films and undesired oxidation from Sn2+ to Sn4+, leading to poor film morphology and coverage, as well as high density defects. Here, we propose a ligand engineering strategy to construct high‐quality phenethylammonium tin iodide (PEA2SnI4) perovskite films by using L‐glutathione reduced (GSH) as surface ligands toward efficient pure red PEA2SnI4‐based PeLEDs. We show that the hydrogen‐bond and coordinate interactions between GSH and PEA2SnI4 effectively reduce the crystallization rate of the perovskites and suppress the oxidation of Sn2+ and formation of defects. The improved pure red perovskite films not only show excellent uniformity, density, and coverage but also exhibit enhanced optical properties and stability. Finally, state‐of‐the‐art pure red PeLEDs achieve a record external quantum efficiency of 9.32 % in the field of PEA2SnI4‐based devices. This work demonstrates that ligand engineering represents a feasible route to enhance the EL performance of Sn‐based PeLEDs. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbX3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) have great application prospects in many fields due to their excellent photoelectric properties. However, CsPbX3 NCs are extremely sensitive to water, heat, light, and oxygen, which leads to dramatic photoluminescence quenching and seriously restricts their future commercial applications. Herein, a novel, simple one‐step solution strategy for synthesizing high‐quality CsPbBr3 NCs was reported. By the combination of the hot‐injection process with the mesoporous template confinement effect of the KIT‐6 matrix, the space‐confined growth of NCs was precisely achieved. The CsPbBr3 NCs encapsulated by KIT‐6 (CsPbBr3@KIT‐6 composite) exhibited a uniform size, a high photoluminescence quantum yield (PLQY) of up to 82%, and a narrow full width at half‐maximum (FWHM) of 24 nm. Most importantly, CsPbBr3@KIT‐6 powder composites had dramatically enhanced light, thermal and water stability in comparison with colloidal CsPbBr3 NCs due to the dual protection of organic ligands and matrix templates. Ultimately, a white light‐emitting diode (LED) device was successfully fabricated by encapsulating a mixture of green‐emitting CsPbBr3@KIT‐6 composite and red‐emitting K2SiF6:Mn4+ phosphor onto a blue‐emitting InGaN LED chip. A color coordinate of (0.327, 0.337) and a wide color gamut of 128% NTSC well demonstrate their potential applications in lighting and display. [ABSTRACT FROM AUTHOR]

All-inorganic perovskite nanocrystals (NCs) have attractive potential for applications in display and lighting fields due to their special optoelectronic properties. However, they still suffer from poor water and thermal stability. In this work, green CsPbBr3-alginic acid (CsPbBr3-AA) perovskite composites were synthesized by an in situ hot-injection process which showed a high photoluminescence quantum yield (PLQY) of 86.43% and improved moisture and thermal stability. Finally, white light-emitting diodes (WLEDs) were fabricated by combining the green CsPbBr3-AA perovskite composites with red K2SiF6:Mn4+ phosphors and blue InGaN LED chips. The WLEDs show a relatively high luminous efficacy of 36.4 lm/W and a wide color gamut (124% of the National Television System Committee). These results indicate that the green CsPbBr3-AA perovskite composites have great potential applications in backlight displays. [ABSTRACT FROM AUTHOR]

All-inorganic halide perovskite nanomaterials have a high application potential in the field of display and lighting because of unique photoelectric properties. However, these materials suffer from problems related to poor water and thermal stabilities. In this study, green Eu3+-doped CsPbBr3/Cs4PbBr6 perovskite composites that were synthesized by a saturated recrystallization method at room temperature showed an enhanced photoluminescence quantum yield of 87% and superior water and thermal stabilities to that of undoped perovskites. Finally, green Eu3+-doped CsPbBr3/Cs4PbBr6 perovskite composites were fabricated into white light-emitting diodes (WLEDs) with a wide color gamut (124% of the National Television System Committee standard) and a high efficiency of 43.06 lm/W. [ABSTRACT FROM AUTHOR]

Abstract: A series of high‐quality Cu‐doped Zn–In–S nanocrystals (d‐NCs) were prepared by a conventional hot injection process. The full‐visible spectrum emission from 480 to 648 nm can be easily achieved by adjusting the Cu doping concentration in the Zn–In–S system, but not by varying the ratio of In/Zn in the alloyed host material. After wrapping the ZnS shell around the Zn–In–S:Cu d‐NCs core, the resultant Zn–In–S:Cu/ZnS core/shell d‐NCs not only exhibited an enhanced prominent photoluminescent quantum yield (PLQY) up to 65% but also possessed the excellent thermal, photochemical stability, and longer PL lifetime. Furthermore, high color rendition white light was generated from a single color converter Zn–In–S:Cu/ZnS core/shell NCs‐assisted white light‐emitting diodes (LEDs). Under operation of 38 mA forward bias current, the fabricated white LEDs emitted bright natural white light with a luminous efficiency of 62 lm/W, and the correlated color temperature of 5658 K. Simultaneously, the good color stability was accompanied by the CIE color coordinates of (0.3287, 0.3527) under different forward bias currents. [ABSTRACT FROM AUTHOR]

This article reports a low-cost yellow-emitting Y3Al5- xB xO12- xN x: Ce3+ phosphor with an enhanced luminescent intensity and excellent thermal stability for white light-emitting diodes ( LEDs). It was synthesized by a simple gas-pressure sintering ( GPS) process. The effect of B3+- N3− incorporation on the optical properties of Y3Al5O12: Ce3+ phosphor was investigated. The addition of appropriate amounts of boron nitride (BN) leads to a marked increase in photoluminescent intensity and a slight shift of its emission spectra toward the blue region, which is assigned to the improved crystallinity and increased particle size. Especially, the prepared oxynitride phosphor does not exhibit any thermal quenching under high temperature, and the emission intensity at 250°C even increases up to 175% of that measured at 20°C. Finally, the white LED flat lamp with luminous efficiency as high as 101 lm/W, color rendering index of 72, and correlated color temperature of about 6600 K is successfully realized by using YAG: Ce3+ phosphor doped with 0.5 molar ratio BN, which is acceptable and promising for general indoor illuminations to replace fluorescent or incandescent lamps. [ABSTRACT FROM AUTHOR]

Graphical abstract The high quality CsPbBr 3 -Cs 4 PbBr 6 perovskite composites solids were synthesized by a single atomic supersaturated recrystallization method. Abstract Here, we present a single atomic supersaturated recrystallization method to synthesize the green-emitting CsPbBr 3 -Cs 4 PbBr 6 perovskite composites in solid state with the highest PLQY of 40.8% in pure polar solvent. The component, morphology, and optical properties of the microcrystals can be tuned by varying growth time, the content of ammonium bromide, and bromine source. The developed method provides a new route to large-scale synthesize high quality perovskite composites emitters for light-emitting diodes. [ABSTRACT FROM AUTHOR]

Abstract The yellow-emitting carbon dots (CDs) were successfully synthesized by a simple one-step hydrothermal route using o-phenylenediamine (o-PD) as the starting material. The emssion peak of CDs shifted from 535 to 563 nm and the corresponding photoluminescence quantum yield (PLQY) enhanced from 10.4% to 23.1% when the reaction solvent of ethanol was replaced by deionized water and reaction temperature was increased by 20 °C. After CDs were effectively and uniformly attached to starch particles by hydrogen bonding and physical adsorption, a new type of environmentally friendly and yellow CDs-based phosphors has been developed. Effective dispersion of small CDs on the surface of large starch particles can lengthen the distance among CDs, as a result, the non-radiative decay process and photoluminescence quenching were steadily hindered. Highly efficient solid-state CDs phosphors with a PLQY of 66.9% were acquired. Combing with the excellent thermal stability and photostability, a daylight white LED based on a single color converter of yellow CDs phosphors was fabricated with a CRI of 83, luminous efficiency of 30.54 lm/W, and CIE coordinates of (0.3429, 0.2817). Suggesting that as-prepared CDs-based phosphors have a great potential in phosphor-based light-emitting devices. [ABSTRACT FROM AUTHOR]

Eu 2+ and Eu 3+ co-doped Ga 2 O 3 nanocrystals (Ga 2 O 3 :Eu NCs) were synthesized in an organic phase at a low reaction temperature of 300 °C. The surface of Ga 2 O 3 :Eu NCs was passivated by oleylamine (OAm) and acetylacetone (acac). The coexistence of Eu 2+ and Eu 3+ as well as passivation by acac and OAm enable Ga 2 O 3 to be excited in the broad spectral range of 200–500 nm. The broadened absorption band is attributed to the strong acac → Ln(III) ligand to the metal charge transfer transition at ∼370 nm, Eu(III) f-f allowed 7 F 0  →  5 L 6 transition at 395 nm, and 7 F 0  →  5 D 2 transition at 465 nm, as well as the efficient electronic transition of Eu(II) 4f → 5d at ∼400 nm. Under near-ultraviolet excitation, white light emission can be achieved by combining orange-red light from f-f electronic transition of Eu(III) with blue-green-yellow light from Ga 2 O 3 oxygen defects levels. Furthermore, the resultant Ga 2 O 3 :Eu NCs with optimized quantum yield of 14.5% were coated onto 395 nm near-ultraviolet chips to fabricate a white light emitting diode. It exhibits a luminous efficiency of 34 lm/W, CIE colour coordinate of (0.2964, 0.2831) and high colour rendering index of 80. [ABSTRACT FROM AUTHOR]

Non-rare-earth, red-emitting CaAl 12 O 19 :Mn 4+ nanofiber phosphors have been successfully prepared by an electrospinning technique followed by an annealing process. The as-prepared precursor fibers have smooth surfaces with an average diameter of 5 µm. After annealing at high temperature, the diameter of the fibers gradually reduces due to the decomposition of the organic polymers. The photoluminescence and crystalline properties of the fibers were investigated as a function of Mn 4+ concentration and the annealing temperature. Under ultraviolet and blue light excitation, CaAl 12 O 19 :Mn 4+ exhibits a characteristic red emission at 655 nm with three satellite peaks due to the 2 E→ 4 A 2 transition of Mn 4+ . The highest PL intensity is achieved at a 0.5% Mn 4+ concentration and a firing temperature of 1400 °C. In comparison to CaAl 12 O 19 :Mn 4+ prepared by a usual solid-state reaction, the luminescence of the as-prepared nanofiber phosphors in the present work has been strongly enhanced by optimizing the morphology and improving the crystallinity and phase purity. The absorption band in the blue region and a bright emission in the red region make the CaAl 12 O 19 :Mn 4+ nanofiber phosphor a candidate for achieving high color rendering in YAG:Ce-based WLEDs. A warm WLED with a high CRI of 88.5 at a CCT of 4553 K has been successfully achieved by coating YAG:Ce with CaAl 12 O 19 :Mn 4+ nanofiber phosphors on blue InGaN chips. [ABSTRACT FROM AUTHOR]

A yellow-orange emitting Lu 3 Al 5− x Si x O 12− x N x :Ce 3+ phosphor with excellent color rendering, high luminescent efficiency and high thermal stability was reported in this paper. It was synthesized by a conventional solid-state reaction method. The effect of Si 4+ –N 3− incorporation on the optical properties of Lu 3 Al 5 O 12 :Ce 3+ phosphor was investigated and compared to YAG:Ce 3+ with the same compositions. Similarly, the addition of α-Si 3 N 4 leads to a distinct redshift and broadening of photoluminescent spectrum, which is assigned to the increased covalency and crystal field strength caused by N 3− . Nevertheless, an excellent thermal stability and a higher integrated intensity presented by α-Si 3 N 4 -doped LuAG:Ce 3+ are distinctive. Further, the emission intensity can be greatly enhanced by adding NaF flux. Finally, the white LED flat lamp with a CRI as high as 83 and a luminous efficiency of 85 lm/W is successfully realized by using a single LuAG-based oxynitride phosphor combined with a blue LED chip, which is completely feasible for general indoor illuminations to replace the traditional fluorescent or incandescent lamps. [ABSTRACT FROM AUTHOR]

Abstract: Thiol-capped and red-emitting CdSe quantum dots (QDs) have been successfully synthesized in the air without hot-injection by one-step microwave method with friendly environment. The size and optical properties can be tuned by changing the reaction time, growth temperature, microwave power, and the Cd2+/Se molar ratio. The as-prepared CdSe QDs were mixed with the yellow-emitting YAG:Ce phosphor and coated onto a blue LED chip, a white LED with an excellent color rendering property was obtained. It exhibited a luminous efficiency of 67lm/W and a Ra as high as 85, which is acceptable for general lighting. It indicates that the combination of the phosphor and QD in LEDs should be a good solution to obtain white light sources with high color rendering. [Copyright &y& Elsevier]

Multi-color carbon dots (CDs) were obtained from cis -butenedioic acid (C-BA) and urea by a simple one-step solvothermal route. This is the first report about using C-BA as the raw material to synthesize CDs. The fluorescent properties of as-prepared CDs vary with the ratio of C-BA to urea. And the sample with 1:1 of C-BA and urea exhibits the optimal yellow emission and highest photoluminescence quantum yield (PLQY) of 16.17%. Further investigations indicate that the variation of PL properties comes from the different content of surface functional groups such as C C, C O, –COOH, and graphitic N. Both of C O and graphitic N cause the PL redshift, whereas the C C and –COOH groups lead to the blueshift. Based on the above, a solid-state luminescent CDs-based phosphor was obtained by adding alkaline Ca(OH) 2 powder to as-prepared yellow CDs solution. In this case, PL intensity is increased to 1.78 times, the corresponding emission redshifts from 553 to 568 nm, and PLQY is improved from 16.17% to 35.12%. Simultaneously, CDs@Ca(OH) 2 hybrid phosphor exhibits good thermostability. Finally, a white light-emitting diode (LED) was successfully fabricated by combining the yellow-emission CDs-based phosphor with a blue LED chip. It exhibits a high CRI of 86.9, the CCT of 5388 K, and a luminous efficacy of 15.12 lm/W. The CIE coordinate locates at (0.3341, 0.3075) which is very close to the pure white light of (0.33, 0.33). Thus, as-prepared CDs-based solid-state phosphor is a potential candidate for practical lighting devices. • This is the first report about using C-BA as the raw material to synthesize CDs. • The PL intensity of CDs @Ca(OH) 2 hybrid phosphors is increased to 1.78 times compared with the CDs solution. • The PL intensity of CDs @Ca(OH) 2 hybrid phosphors could be maintained to 34.4% when heated in the air from 30 to 240 °C. • The CIE coordinate locates at (0.3341, 0.3075), very close to the pure white light of (0.33, 0.33). [ABSTRACT FROM AUTHOR]

• Zn2+ ions were successfully doped into CsPbBr 3 NCs with a high PLQY of 91.3% and a narrow FWHM of 15.5 nm. • The doped NCs not only have improved optical properties but also exhibit excellent stability. • The CsPbBr3:Zn2+ NCs based WLED shows wide color gamut (137% of NTSC). All-inorganic cesium lead halide perovskite nanocrystals (NCs) are considered as an excellent candidate material for light-emitting devices (LED) displays because of their great photo-physical properties. However, the efficiency and stability of these materials are still unsatisfactory, which is the main disadvantage hindering the commercialization of the perovskite NCs based LED displays. On the other hand, the poisonous element lead (Pb) restricted the large-scale application of the perovskite NCs. Here we reported a hot-injection method by doping zinc ions into the CsPbBr3 NCs with enhanced photoluminescence (PL) properties and stability in ambient air. The doped NCs exhibit the highest photoluminescence quantum yield (PLQY) of 91.3% and a narrow full width at half-maximum (FWHM) of 15.5 nm. The improved the optical properties and stability of the doped NCs may result from the enhanced formation energies of perovskite lattices and the surface passivation. Finally, a white light-emitting diode (WLED) was fabricated by combining the green-emitting CsPbBr 3 :Zn2+ doped NCs and red-emitting K 2 SiF 6 :Mn6+ phosphors along with a blue LED chip, which exhibits a luminous efficiency of 36 lm/W, a chromaticity coordinate of (0.327, 0.336), a color temperature (CCT) of 5760 K and a wide color gamut (137% of the National Television System Committee). [ABSTRACT FROM AUTHOR]