High‐Performance White Emission from Cu‐Based Perovskite Compound

Self-trapped exciton (STE) emission stands out for its large Stokes shift, broad emission spectrum, and high photoluminescence quantum yield (PLQY). In this work, we developed an Sb3+-doped low-dimensional layered halide, Cs2CdBr2Cl2, as a system to achieve efficient broadband emission. By fine-tuning the Sb3+ doping concentration, we induced moderate lattice distortion, resulting in a suitable Huang–Rhys factor (S = 18.00) and a high exciton binding energy (Eb = 144.73 meV), which collectively enabled strong yellow STE emission with a PLQY of nearly 80%. Experimental and theoretical investigations reveal that the emission originates from STE states associated with distorted [SbCl4Br2]3– octahedra. This highly efficient luminescent material, when combined with commercial phosphors, achieves a high color rendering index (Ra) of 90.8 and exhibits excellent radiation resistance and great potential for X-ray imaging applications.

Microwave synthesis of composite of AgInS2 quantum dots and zeolitic imidazolate framework-8 for application in white light emitting diodes

Lead‐free organic–inorganic metal halides (OIMHs) are highly desirable owing to their remarkable properties including low toxicity, structural diversity, high stability, and solution processability. Nevertheless, the development of their single‐component white emissive films remains a formidable challenge for remote white light‐emitting diodes (WLEDs) application. In this work, (C 16 H 36 N) 2 Cu 2 I 4 /polyvinylidene fluoride (PVDF) white emissive composite film is successfully fabricated through an in situ solvent evaporation crystallization process at room temperature. The elemental analysis and bonding between (C 16 H 36 N) 2 Cu 2 I 4 and PVDF are demonstrated by X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) measurements. In addition, this composite film exhibits a broadband white emission with two peaks. Notably, the best photoluminescence quantum yields (PLQYs) of the PVDF based composite film reaches an impressive 96.7%. A (C 16 H 36 N) 2 Cu 2 I 4 /PVDF based remote UV‐pumped WLEDs with an impressive color rendering index of 95.5 is realized. Finally, the in situ fabrication method is expanded to fabricate (C 16 H 36 N) 2 Cu 2 I 4 /polyacrylonitrile (PAN) composite films, and we further realized their single component remote WLEDs.

Unity emission in organic phosphonium antimony halide for high color rendering white LED

Achieving highly fluorescent and stable perovskite materials has remained a significant challenge in recent years. While several works have reported high photoluminescence and moderate stability in various perovskite systems, this study reports for the first time a photoluminescence quantum yield of 100% with exceptional stability through lanthanide doping of the Cs2Na0.9Ag0.1In0.95Bi0.05Cl6 double perovskite. The lanthanide doping process resulted in a strong and efficient broadband self-trapped exciton (STE) emission. Remarkably, the Yb3+-doped Cs2Na0.9Ag0.1In0.95Bi0.05Cl6, and Er3+-doped Cs2Na0.9Ag0.1In0.95Bi0.05Cl6 sample exhibited a warm-white light emission with near-unity PLQY of 99.8% and 100%, respectively, while the pristine sample delivered a 2.3% PLQY only. Structural characterization confirmed the high purity of the samples with near-stoichiometric composition of the materials, with no detectable evidence for secondary phases. The samples maintained their superior emission properties over extended periods of testing. When assembled into a white-light-emitting diode (WLED), the materials generated a strong broadband luminescence (EL) with an excellent color rendering index (CRI) of 91.3 and a correlated color temperature (CCT) of 2826 K, achieving a highly efficient and stable performance. This study highlights that lead-free double perovskites can be reliable and highly efficient materials for commercial LED devices, paving the way for a more sustainable and efficient lighting solution.

Easy-to-perform organic-solvent-free synthesis of carbon dots with strong green photoluminescence

Developing single-component materials with bright-white emission is required for energy-saving applications. Self-trapped exciton (STE) emission is regarded as a robust way to generate intrinsic white light in halide perovskites. However, STE emission usually occurs in low-dimensional perovskites whereby a lower level of structural connectivity reduces the conductivity. Enabling conventional three-dimensional (3D) perovskites to produce STEs to elicit competitive white emission is challenging. Here, we first achieved STEs-related emission of white light with outstanding chromaticity coordinates of (0.330, 0.325) in typical 3D perovskites, Mn-doped CsPbBr3 nanocrystals (NCs), through pressure processing. Remarkable piezochromism from red to blue was also realized in compressed Mn-doped CsPbBr3 NCs. Doping engineering by size-mismatched Mn dopants could give rise to the formation of localized carriers. Hence, high pressure could further induce octahedra distortion to accommodate the STEs, which has never occurred in pure 3D perovskites. Our study not only offers deep insights into the photophysical nature of perovskites, it also provides a promising strategy towards high-quality, stable white-light emission.

The outstanding emission of halide perovskites make them ideal candidates for white emission light-emitting diodes (LEDs) for lighting applications. However, many perovskites contain toxic or scarce elements and have unsatisfactory stability. Here, we report a target-driven approach, based on active learning (AL) techniques, to discover halide perovskites suitable for commercial LED applications. Based on the similarity between halide and oxide perovskites, a model trained on an oxide perovskite dataset plus six AL-selected halide perovskites exhibited excellent performance for photoluminescence quantum yield (PLQY) predictions of oxide and halide perovskites. The model proposed a strong relationship between ionic radii and PLQY, postulated to be due to the self-trap excitons derived from the Jahn-Teller deformation. A novel halide perovskite phosphor, Cs4Zn(Bi0.85Sb0.15)2Cl12:0.01Mn, was designed and synthesized with the aid of the model. It exhibited an 88 % PLQY and outstanding thermal and luminescent stability. A simple white LED was fabricated from this material, exemplifying its commercial potential. This study demonstrates how machine learning techniques can accelerate discovery of next-generation phosphors for high performance single emitter-based white-light emitting devices.

Complementary ligand decorated cesium lead bromide nanoplatelets for high performance light-emitting diodes

Luminescent metal nanoclusters are of great importance as an alternative to rare-earth phosphors for white light-emitting diodes (WLEDs), but they usually show low photoluminescence quantum yield (PLQY) due to a lack of effective control over relaxation and radiation induced by kernel-ligand interaction. Here, a hydrolysis-delayed coordination synthetic strategy is developed in 8-hydroxyquinoline-based tin-oxo clusters covering from doubly vertex-missed icosahedral Sn10 to icosahedral Sn12 and Sn12-Me. 99.29% ultrabright green PLQY is achieved in Sn12, exhibiting a 6.4-fold enhancement compared to 15.43% in Sn10. Femtosecond transient absorption spectroscopy and time-dependent density functional theory reveal a kernel-regulated ligand-centered emission mechanism: the rigid kernel suppresses nonradiative decay through core-to-shell confinement effects, while structural deformation in an unstable kernel disrupts electronic coupling, thereby reducing radiative transitions. Sn12-based WLEDs demonstrate a high color rendering index of up to 87.7, as well as adjustable correlated color temperature. This work provides key insight into high PLQY and suitable solid-state lighting luminescent nanoclusters via kernel regulation.

Lead‐free low‐dimensional organic–inorganic metal halides have gained increasing attention in a wide range of applications due to their low toxicity, outstanding optical performance, and structural tunability. In this work, a general method of incorporating organic molecule into sodium antimony bromides is introduced. The 1D Na3SbBr6(C2H6OS)6 and Na3SbBr6(C4H8OS)6 single crystals exhibit bright yellow and orange emission with PL peaks at 610 and 664 nm, and high photoluminescence quantum yields (PLQYs) of 85% and 60%, respectively. These two compounds can be reversibly converted into each other by the removal and addition of the organic components. Their exceptional luminescent performance enables them to be used as solid‐state phosphors for the fabrication of yellow and orange down‐conversion LEDs. A white LED with a high color rendering index (CRI) of 95 is also fabricated by using Na3SbBr6(C2H6OS)6 as the yellow phosphor. The universality of this method is demonstrated by synthesizing other members of this family with diverse A‐groups, including methylammonium (MA) and formamidinium (FA). This work provides an effective strategy for the development of diverse lead‐free and high‐performance organic–inorganic hybrid materials and indicates these organic–inorganic hybrid compounds are promising luminescent materials for lighting or displays.

Phosphor‐converted white‐light‐emitting diodes (pc‐wLED) have been widely used for general lighting because of their advantages of energy saving, high efficiency, long lifetime, environmentally friendly, etc. However, it is still a great challenge to obtain full‐spectrum wLEDs with super‐high color rending index (CRI) due to the cyan cavity (a gap between the blue and green emissions in the range of 480–520 nm). The lead‐free all‐inorganic cesium copper halide phosphor β‐Cs3Cu2Cl5 shows an interesting cyan‐green emission. Herein, a novel synthesis method based on low‐temperature evaporation recrystallization is demonstrated. β‐Cs3Cu2Cl5 shows an intense and broad emission band centered at 526 nm, a full width at half maximum (FWHM) of 112 nm, and a photoluminescence quantum yield (PLQY) of 97.3%. The broad‐band cyan‐green emission is assigned to the self‐trapping excitons (STEs) based on the calculation and experimental results. Super‐high color rendering wLEDs can be created by pumping the β‐Cs3Cu2Cl5, BaMgAl10O17:Eu2+ (blue), and (Sr,Ca)AlSiN3:Eu2+ (red) phosphor mixtures by a 365 nm UV LED chip, which exhibits a CRI of 96 (R9 = 83 and R12 = 93) and a correlated color temperature (CCT) of 4203 K. It demonstrates that the cyan‐green‐emitting β‐Cs3Cu2Cl5 phosphor would be potentially applied in full‐spectrum wLEDs for high‐quality general lighting.

Carbon dots (CDs), one of the most significant classes of carbon-based nanophosphors, have attracted extensive attention in recent years. However, few attempts have been reported for realizing CDs with tunable emissions, especially for obtaining the red-light emissions with high photoluminescence quantum yields. Herein, we synthesized CDs with different chromatic blue, green and red emissions by facilely changing the reaction solvent during hydrothermal conditions. The photoluminescence quantum yields of 34%, 19% and 47% for the blue, green and red emissions, respectively, were achieved. Furthermore, the solid-state CD/PVA composite films were constructed through mixing the CDs with PVA polymer, in which the self-quenching of photoluminescence of CDs had been successfully avoided benefiting from the formation of hydrogen bonds between the CDs and PVA molecules. Finally, the warm white light emitting diode (WLED) was fabricated by integrating CD/PVA film on a UV-LED chip. The WLED exhibited the Commission International de l’Eclairage coordinates (CIE) of (0.38, 0.34), correlated color temperature of 3913 K and color rendering index of 91, respectively, which were comparable with the commercial WLEDs.

A highly efficient and easily tunable luminescence is significant for solid-state luminescent (SSL) materials. However, achieving a photoluminescence quantum yield (PLQY) close to unity and tuning the emission remain challenging tasks. Metal doping strategies enable resolution of these issues. Herein, we report the preparation of a novel organic-inorganic lead-free indium-based metal halide hybrid (MP)3InCl6•EtOH (MP = C4H10ON) with a typical zero-dimension structure. When excited at 320 nm, (MP)3InCl6•EtOH exhibits a dual emission band at 420 and 600 nm, which originates from the organic cation [MP] and the [InCl6]3- octahedral unit. The photoluminescence can be significantly enhanced through Sb3+ doping, resulting in an increase in PLQY from 0.78% to near unity. Multiple emission color tunings have been achieved by regulating the Sb doping level and the radiation wavelength, resulting in a change in emission color from blue → white → orange. Optical characterizations reveal that the significantly enhanced emission centered at 600 nm can be attributed to more efficient absorption, closely associated with an additional 1S0 → 3P1 transition in the inorganic octahedron [In(Sb)Cl6]3- due to Sb3+ doping. With its excellent optical performance, a white light emitting diode (WLED) has been successfully fabricated by coating the mixture of (MP)3InCl6•EtOH:15%Sb3+ with blue phosphor BaMgAl10O17:Eu2+ onto a UV LED chip. The WLED device exhibits perfect white light emission with regard to the International Commission on Illumination (CIE) coordinates of (0.36, 0.34). Significantly, the WLED device maintains a stable correlated color temperature (CCT) range of 4119-4393 K and CIE coordinates (x: 0.37-0.34, y: 0.35-0.33) as the driven current varies from 20 to 200 mA, demonstrating outstanding stability across different power levels. This work not only presents a novel system for achieving remarkably enhanced luminescent performance and tuning emission bands in 0D metal halides but also represents a significant step toward achieving resistance to color drifting for stable WLEDs.

Materials for radiation detection are critically important and urgently demanded in diverse fields, starting from fundamental scientific research to medical diagnostics, homeland security, and environmental monitoring. Low-dimensional halides (LDHs) exhibiting efficient self-trapped exciton (STE) emission with high photoluminescence quantum yield (PLQY) have recently shown a great potential as scintillators. However, an overlooked issue of exciton-exciton interaction in LDHs under ionizing radiation hinders the broadening of its radiation detection applications. Here, we demonstrate an exceptional enhancement of exciton-harvesting efficiency in zero-dimensional (0D) Cs3Cu2I5:Tl halide single crystals by forming strongly localized Tl-bound excitons. Because of the suppression of non-radiative exciton-exciton interaction, an excellent α/β pulse-shape-discrimination (PSD) figure-of-merit (FoM) factor of 2.64, a superior rejection ratio of 10−9, and a high scintillation yield of 26 000 photons MeV−1 under 5.49 MeV α-ray are achieved in Cs3Cu2I5:Tl single crystals, outperforming the commercial ZnS:Ag/PVT composites for charged particle detection applications. Furthermore, a radiation detector prototype based on Cs3Cu2I5:Tl single crystal demonstrates the capability of identifying radioactive 220Rn gas for environmental radiation monitoring applications. We believe that the exciton-harvesting strategy proposed here can greatly boost the applications of LDHs materials.