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Phosphor-glass composites (PGC) are excellent candidates for highly efficient and stable photonic converters; however, their synthesis generally requires harsh procedures and long time, resulting in additional performance loss and energy consumption. Here we develop a rapid synthetic route to PGC within about 10 seconds, which enables uniform dispersion of Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce) phosphor particles through a particle self-stabilization model in molten tellurite glass. Thanks for good wettability between YAG:Ce micro-particles and tellurite glass melt, it creates an energy barrier of 6.94 × 10 5 zJ to prevent atomic-scale contact and sintering of particles in the melt. This in turn allows the generation of YAG:Ce-based PGC as attractive emitters with high quantum efficiency (98.4%) and absorption coefficient (86.8%) that can produce bright white light with luminous flux of 1227 lm and luminous efficiency of 276 lm W −1 under blue laser driving. This work shows a generalizable synthetic strategy for the development of functional glass composites. Phosphor-glass composites can serve as efficient and stable photonic converters, but their synthesis generally requires harsh and time-consuming procedures. Here, the authors report an alternative synthesis route that requires only a few seconds and is based on particle self-stabilization.

Innovative materials for phosphor converted white light-emitting diodes are in high demand owing to the huge potential of the light-emitting diode technology to reduce energy consumption worldwide. As the primary blue diode is already highly optimized, the conversion phosphors are of crucial importance for any further improvements. We report on the discovery of the high performance red phosphor Sr[Li 2 Al 2 O 2 N 2 ]:Eu 2+ meeting all requirements for a phosphor’s optical properties. It combines the optimal spectral position for a red phosphor, as defined in the 2016 Research & Development-plan of the United States government, with an exceptionally small spectral full width at half maximum and excellent thermal stability. A white mid-power phosphor-converted light-emitting diode prototype utilising Sr[Li 2 Al 2 O 2 N 2 ]:Eu 2+ shows an increase of 16% in luminous efficacy compared to currently available commercial high colour-rendering phosphor-converted light-emitting diodes, while retaining excellent high colour rendition. This phosphor enables a big leap in energy efficiency of white emitting phosphor-converted light-emitting-diodes. Developing innovative materials for reduced energy consumption in phosphor converted white light-emitting diodes remains a challenge. Here, the authors report a narrow band red-emitting oxonitride material with a highly symmetrical Sr2 + coordination for energy efficient white light-emitting diodes.

Perovskite light-emitting diodes (PeLEDs) based on three-dimensional (3D) polycrystalline perovskites suffer from ion migration, which causes overshoot of luminance over time during operation and reduces its operational lifetime. Here, we demonstrate 3D/2D hybrid PeLEDs with extremely reduced luminance overshoot and 21 times longer operational lifetime than 3D PeLEDs. The luminance overshoot ratio of 3D/2D hybrid PeLED is only 7.4% which is greatly lower than that of 3D PeLED (150.4%). The 3D/2D hybrid perovskite is obtained by adding a small amount of neutral benzylamine to methylammonium lead bromide, which induces a proton transfer from methylammonium to benzylamine and enables crystallization of 2D perovskite without destroying the 3D phase. Benzylammonium in the perovskite lattice suppresses formation of deep-trap states and ion migration, thereby enhances both operating stability and luminous efficiency based on its retardation effect in reorientation. Ion migration can induce overshoot of luminance in normal 3D perovskite light-emitting diode devices and results in reduced lifetime. Here Kim et al. show that the ion migration and overshoot can be suppressed in 3D/2D hybrid perovskites, leading to 21 times longer operational lifetime.

Inorganic phosphors have been crucial in enabling energy-efficient, phosphor-converted light-emitting diode (LED) lighting and display technologies. The push to increase the luminous efficacy and improve the colour quality of these lights has led to a surge in reports of different combinations of phosphor host structures and activators, with many claiming that the new materials have transformative properties. This Perspective article outlines the optical property requirements phosphors must meet to impact the field. Additionally, the tools that have been developed to accelerate the discovery of exceptional phosphors that meet these requirements are summarized, including crystal–chemical design rules, proxies, data-driven approaches, first-principles calculations and combinatorial methods. We also highlight open challenges in the field of phosphor discovery. Finally, we discuss the reality that these methods are unlikely to identify a perfect phosphor that satisfies all the requirements. Instead, we propose a workflow for phosphor discovery that prioritizes the properties necessary to produce next-generation phosphor materials. Phosphors are important for optimizing the energy efficiency and colour quality of modern light-emitting diode light bulbs and displays. This Perspective article discusses the optical properties required for a phosphor to be viable for commercialization and the synthetic and data-driven methods that have been developed to accelerate the discovery of phosphor materials with these properties.

Perovskite light-emitting diodes have drawn great attention in the fields of displays and lighting, especially for applications requiring high efficiency and high brightness. While three-dimensional perovskite light-emitting diodes hold promise for achieving higher brightness compared to low-dimensional counterparts, efficient blue three-dimensional perovskite light-emitting diodes have remained a challenge due to defect formation during the disordered crystallization of multiple A-cation perovskite. Here we demonstrate an all-site alloy method that enables sequential A-site doping growth of formamidinium and cesium hybrid perovskite. This approach significantly reduces the trap density of the perovskite film by approximately one order of magnitude. Consequently, we achieve efficient and bright blue perovskite light-emitting diode with an external quantum efficiency of 23.3%, a luminous efficacy of 33.4 lm W −1 , and a luminance of approximately 5700 cd m −2 for the emission with a peak at 487 nm. This work provides a strategy for growing high-quality multicomponent perovskite for optoelectronics. Chen et al. report all-site alloying for 3D perovskites where B-site strontium doping retards the crystallisation and induces sequential A-site doping with annealing. The controllable crystallisation enables blue LEDs with peak efficiency of 23.3% at 487 nm and tuneable emission to 463 nm.

HighlightsThis article reviews the recent progress in the patterning techniques of metal halide perovskites for full-color displays.Patterning techniques of perovskites are subdivided into in situ crystallization and patterning of colloidal perovskite nanocrystals, including photolithography, inkjet printing, thermal evaporation, laser ablation, transfer printing, and so on.The strength and weakness of each patterning methods are discussed in detail from the viewpoint of their applications in full-color displays.Metal halide perovskites have emerged as promising light-emitting materials for next-generation displays owing to their remarkable material characteristics including broad color tunability, pure color emission with remarkably narrow bandwidths, high quantum yield, and solution processability. Despite recent advances have pushed the luminance efficiency of monochromic perovskite light-emitting diodes (PeLEDs) to their theoretical limits, their current fabrication using the spin-coating process poses limitations for fabrication of full-color displays. To integrate PeLEDs into full-color display panels, it is crucial to pattern red–green–blue (RGB) perovskite pixels, while mitigating issues such as cross-contamination and reductions in luminous efficiency. Herein, we present state-of-the-art patterning technologies for the development of full-color PeLEDs. First, we highlight recent advances in the development of efficient PeLEDs. Second, we discuss various patterning techniques of MPHs (i.e., photolithography, inkjet printing, electron beam lithography and laser-assisted lithography, electrohydrodynamic jet printing, thermal evaporation, and transfer printing) for fabrication of RGB pixelated displays. These patterning techniques can be classified into two distinct approaches: in situ crystallization patterning using perovskite precursors and patterning of colloidal perovskite nanocrystals. This review highlights advancements and limitations in patterning techniques for PeLEDs, paving the way for integrating PeLEDs into full-color panels.

LED is widely used due to its many advantages. As the fourth generation lighting source, it has always been limited by its luminous efficiency. How to improve the luminous efficiency of LED is one of the current research hotspots. The paper aims to conduct a limited analysis of the luminous efficiency of LED and provide theoretical support for LED luminescence research. Firstly, theoretical analysis and derivation were conducted on the luminous efficiency of LED, and it was found that the main factor determining its luminous efficiency is the light extraction efficiency of LED. Then, the optical path of internal photons during LED emission was analyzed, and the calculation formula for the limit value of traditional rectangular LED luminous efficiency was derived. Based on the formula, it was found that GaN LED has the highest luminous efficiency limit among the most common LEDs, but it is only 27.3%. Finally, two methods to break through the limit of LED luminous efficiency were proposed in theory, and simulation verification was carried out using TracePro software. By selecting a semiconductor material with a refractive index of 2.2 to make the luminous layer of LED, the luminous efficiency limit of LED can be increased to 30%. The improvement of the LED luminous efficiency limit can also be achieved by changing the light path of photons in the LED. In this paper, two different LED shapes from traditional rectangular shapes were simulated, and their luminous efficiency limit values were greatly improved, reaching a maximum of 40.7%. The limit calculation theory in the paper can provide theoretical support for most current research on LED luminous efficiency.

Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue perovskite LED remains a significant challenge. Three-dimensional mixed-halide perovskites have potential to achieve high brightness electroluminescence, but their emission spectra are unstable as a result of halide phase separation. Here, we reveal that there is already heterogeneous distribution of halides in the as-deposited perovskite films, which can trace back to the nonuniform mixture of halides in the precursors. By simply introducing cationic surfactants to improve the homogeneity of the halides in the precursor solution, we can overcome the phase segregation issue and obtain spectrally stable single-phase blue-emitting perovskites. We demonstrate efficient blue perovskite LEDs with high brightness, e.g., luminous efficacy of 4.7, 2.9, and 0.4 lm W -1 and luminance of over 37,000, 9,300, and 1,300 cd m -2 for sky blue, blue, and deep blue with Commission Internationale de l’Eclairage (CIE) coordinates of (0.068, 0.268), (0.091, 0.165), and (0.129, 0.061), respectively, suggesting real promise of perovskites for LED applications.

Organic light-emitting diodes (OLEDs) suffer from notorious light trapping, resulting in only moderate external quantum efficiencies. Here, we report a facile, scalable, lithography-free method to generate controllable nanostructures with directional randomness and dimensional order, significantly boosting the efficiency of white OLEDs. Mechanical deformations form on the surface of poly(dimethylsiloxane) in response to compressive stress release, initialized by reactive ions etching with periodicity and depth distribution ranging from dozens of nanometers to micrometers. We demonstrate the possibility of independently tuning the average depth and the dominant periodicity. Integrating these nanostructures into a two-unit tandem white organic light-emitting diode, a maximum external quantum efficiency of 76.3% and a luminous efficacy of 95.7 lm W −1 are achieved with extracted substrate modes. The enhancement factor of 1.53 ± 0.12 at 10,000 cd m −2 is obtained. An optical model is built by considering the dipole orientation, emitting wavelength, and the dipole position on the sinusoidal nanotexture. For organic light-emitting diodes (OLEDs) to reach their potential for lighting applications, improved light out-coupling using industry-compatible methods are required. Here, the authors report reactive ion etching-induced quasi-periodic nanostructures for improved light extraction in white OLEDs.

A series of Y 2.985 Al 5– x Ga x O 12 :0.015Ce (YAGG:Ce, x = 0, 1, 2, 3, 4, 5) transparent ceramics were prepared via a solid-state reaction method. Two-step sintering technique was proved to be an effective approach to prepare functional ceramics with high Ga concentration, and Y 3 Ga 5 O 12 (YGG) transparent ceramic was successfully prepared for the first time. According to the variation of Al/Ga ratio, regulation of band structure and luminescence properties of YAGG:Ce transparent ceramics were effectively investigated. When Ga substitutes Al sites, the tetrahedral site is more favorable compared to the octahedral site for Ga to occupy according to the first-principle calculation. A continuous blue shift of the emission from 565 to 515 nm was achieved as Ga was gradually introduced into Y 3 Al 5 O 12 :Ce matrix. High quality green light was obtained by coupling the YAGG:Ce ceramics with commercial blue InGaN chips. Transparent luminescence ceramics accomplished in this work can be quite prospective for high power LED application.