High Photoluminescence Quantum Efficiency Research Articles

Giant Red‐Shifted Emission in (Sr,Ba)Y2O4:Eu2+ Phosphor Toward Broadband Near‐Infrared Luminescence

AbstractNear‐infrared (NIR) light‐emitting diodes (LEDs) light sources are desirable in photonic, optoelectronic, and biological applications. However, developing broadband red and NIR‐emitting phosphors with good thermal stability is always a challenge. Herein, the synthesis of Eu2+‐activated SrY2O4 red phosphor with high photoluminescence quantum efficiency and broad emission band ranging from 540 to 770 nm and peaking at 620 nm under 450 nm excitation is designed. Sr/Ba substitution in SrY2O4:Eu2+ has been further utilized to achieve tunable emission by modifying the local environment, which facilitates the giant red‐shifted emission from 620 to 773 nm while maintaining the outstanding thermal stability of SrY2O4:Eu2+. The NIR emission is attributed to the enhanced Stokes shift and crystal field strength originated from the local structural distortions of [Y1/Eu1O6] and [Y2/Eu2O6]. The investigation in charge distribution around Y/Eu provides additional insight into increasing covalency to tune the emission toward the NIR region. As‐fabricated NIR phosphor‐converted LEDs demonstration shows its potential in night‐vision technologies. This study reveals the NIR luminescence mechanism of Eu2+ in oxide‐based hosts and provides a design principle for exploiting Eu2+‐doped NIR phosphors with good thermal stability.

Achieving host-free near-ultraviolet electroluminescence via electronic state engineering with phosphine oxide

Developing near-ultraviolet (NUV) emitters with board band gap and high photoluminescence quantum efficiency (PLQY) is a formidable challenge for organic light-emitting diode (OLED) applications. Herein, two NUV emitters PhImPOCz and PhImPOtBuCz were designed on the basis of phosphine oxide (PO) modification. It is showed that based on crescent phenanthrene (Phen) fused with acceptor imidazole (Im) as NUV chromophore, carbazole (Cz) or 3,6-di-tertbutyl carbazole (tBuCz) donors make the molecule bipolar character to balance carrier recombination in emissive layer (EML). More significantly, besides steric hindrance for aggregation suppression, the introduction of triphenylphosphine enhances localized excited feature of the electronic states, and prevents the red shift induced by intra- and inter- molecular charge transfer, which establishes the basis for fabricating host-free NUV OLEDs. The non-doped devices based on the PhImPOCz and PhImPOtBuCz emitters achieved the low turn-on voltages of 4.2 V and 4.4 V, and the state-of-the-art external quantum efficiency (EQE) up to 2.81% and 3.42%, respectively. This work demonstrates the significance of electronic state engineering for high-energy OLED applications.

A Series of Fused Carbazole/Carbonyl Based Blue to Yellow‐Green Thermally Activated Delayed Fluorescence Materials for Efficient Organic Light‐Emitting Diodes

AbstractThe exploitation of novel fused carbazole/carbonyl emitters is essential to broaden the application of thermally activated delayed fluorescence (TADF) materials for organic light‐emitting diodes (OLEDs). Here, with the aid of the addition and cyclization of the cyano group with the ortho‐carbazole, fused carbazole/carbonyl based TADF emitters are effectively synthesized via this new synthetic strategy. The attachment of ancillary donors including carbazole, diphenylamine, and phenolazine to the fused carbazole/carbonyl skeletons further tunes their emissions from blue to yellow‐green. Particularly, pure‐blue OLEDs incorporating the peripheral carbazole attached emitter exhibit a maximum external quantum efficiency (EQEmax) of 22.3%, with a small full width at half maximum (FWHM) of 48 nm. In addition, the peripheral phenolazine attached yellow‐green emitter shows extremely small singlet−triplet state energy gap (ΔEST) of 0.01 eV, high photoluminescence quantum efficiency of 82.5%, short delayed fluorescence lifetime of 6.2 µs and good OLED performances with an EQEmax of 21.7%, an FWHM of 68 nm and low efficiency roll‐off. These results demonstrate that the new synthetic strategy for fused carbazole/carbonyl molecules provide a valuable reference for the design of high‐efficient TADF emitters.

Stability of electroluminescent perovskite quantum dots light‐emitting diode

AbstractColloidal quantum dots (QDs) are considered to be a promising candidate for light‐emitting diodes (LEDs) applications considering their wide gamut range, simple color tuning, compatibility with large‐size and flexible substrates. Benefiting from the distinguished properties such as high photoluminescence quantum efficiency (PLQY), narrow emission linewidth, and low material cost, perovskite QDs have attracted wide attention from researchers. Despite tremendous progress has been made during the past several years, perovskite QDs‐based LEDs (QLEDs) are still plagued by the instability arising from the operation of the perovskite QLEDs, which have not been studied systematically. In this review, the origin of the instability of perovskite QLEDs is attributed to the vulnerability of emission materials and constituent layers. Simultaneously, the effective strategies to improve the durability of perovskite QDs and QLEDs are summarized, such as component engineering, ligand passivation, fabrication of robust and uniform constituent layers, as well as adopt appropriate device structures and driving modes. Ultimately, we put forward insights on the future research direction and prospects for perovskite QLEDs in practical applications.

Bright near-infrared aggregation-induced emission dots for long-term bioimaging in vitro/vivo

Advanced hepatocarcinoma is almost incurable and has caused a huge number of deaths every year. Noninvasive long-term cell tracing is an efficient and important tool to understand genesis, development and evolution of cancer cells. Bright organic luminescent dots (named TNZ2tPPI-Tat NPs) with unique aggregation-induced near-infrared red emission (NIR-AIE), prepared in this contribution, enjoy the advantages of desirable biocompatibility, great water dispersibility, high photoluminescent quantum efficiency (32 %), large Stokes shift (166 nm), anti-background interference and great photostability. Moreover, the thus-obtained AIE-active NPs show ultralong fluorescent bioimaging (7 days) in MHCC97-H cells, and still keep clear fluorescent signals after 5 generations in three hepatic cells (Lo2, MHCC97-H, Hep 3B). In vivo fluorescent imaging demonstrates that TNZ2tPPI-Tat NPs still maintain strong brightness over 26 days, suggest great stability of such bright NPs. Further compare with the counterparts of commercial fluorescent probes such as Cy5 and AF647, such AIE dots enjoy more superior performances in the aspect of fluorescent intensity and long-term bioimaging efficiency, which is promising candidate to serve as noninvasive long-term cell tracker.

Developing Efficient Dinuclear Pt(II) Complexes Based on the Triphenylamine Core for High-Efficiency Solution-Processed OLEDs.

The various applications of dinuclear complexes have attracted increasing attention. However, the electroluminescence efficiencies of dinuclear Pt(II) complexes are far from satisfactory. Herein, based on the triphenylamine core, we develop four dinuclear Pt(II) complexes that cover the emission colors from yellow to red with high photoluminescence quantum efficiencies of up to 0.79 in doped films. The solid-state structure of PyDPt is revealed by the single-crystal X-ray diffraction investigation. Besides, solution-processed OLEDs have been fabricated with different electron transport materials. With higher electron mobility and excellent hole-blocking ability, 1,3,5-tri(m-pyridin-3-ylphenyl)benzene (TmPyPB) can help to realize good charge balance in related OLEDs. In addition, angle-dependent PL spectra reveal the preferentially horizontal orientation of these dinuclear Pt(II) complexes in doped CBP films, which benefits the outcoupling efficiencies. Therefore, the yellow OLED based on PyDPt shows unexpected high performance with a peak current efficiency of up to 78.7 cd/A and an external quantum efficiency of up to 22.4%, which is the highest EQE reported for OLEDs based on dinuclear Pt(II) complexes so far. This study demonstrates the great potential of developing dinuclear Pt(II) complexes for achieving excellent electroluminescence efficiencies.

Chiral Thermally Activated Delayed Fluorescence Materials Based on R/S‐N2,N2′‐Diphenyl‐[1,1′‐binaphthalene]‐2,2′‐diamine Donor with Narrow Emission Spectra for Highly Efficient Circularly Polarized Electroluminescence

AbstractIn this study, two pairs of chiral thermally activated delayed fluorescence (TADF) materials enabling circularly polarized luminescence (CPL) named R/S‐p‐BAMCN (rod‐shape) and R/S‐o‐BAMCN (helix‐shape) are prepared based on a new pair of chiral donor (D*), R/S‐N2,N2′‐diphenyl‐[1,1′‐binaphthalene]‐2,2′‐diamine (R/S‐BAM), and two cyano (CN) acceptors. Due to the rigid molecular structure and special intramolecular arrangement, the chiral TADF materials show high photoluminescence quantum efficiency (up to 0.86) with narrow full‐width at half‐maximum (38 nm in cyclohexane, 51 nm in toluene) and photoluminescence dissymmetry factor (|gPL|) up to 5.3 × 10−3. Particularly, the circularly polarized OLEDs (CP‐OLEDs) with rod‐shaped R/S‐p‐BAMCN as the emitter show high device performances with the maximum external quantum efficiency nearing 28%. Meanwhile, the semi‐transparent CP‐OLEDs based on helix‐shaped R/S‐o‐BAMCN exhibit obvious circularly polarized electroluminescence (CPEL) properties with the electroluminescence |gEL| factors around 4.6 × 10−3. The strategy of rigid D*‐A‐D* structure with special arrangement of chiral donor provides a direct way to obtain efficient CP‐TADF materials with narrow emission spectra and promising CPL properties for better CPEL performance.

Ultra-bright pure green perovskite light-emitting diodes

Inorganic perovskites, such as CsPbX3 (X = Cl, Br, I), have attracted attention due to their excellent thermal stabilities and high photoluminescence quantum efficiencies. Here, we report on all-inorganic light-emitting diodes (LEDs), including inorganic perovskite emitters (CsPbBr3) based on the heterostructure of n-ZnO/Al2O3/CsPbBr3/p-GaN. The effects of the CsPbBr3 and Al2O3 interlayers on the electroluminescence performance have been systematically investigated. It is observed that the Al2O3 interlayer plays an important role in determining the emission performance. By introducing the Al2O3 layers, the electron–hole recombination can almost be limited within the perovskite. The emission peaks of the heterojunction LEDs change from blue-green to pure green with the increased luminous intensities and decreased leakage currents. It provides an idea for the preparation of all-inorganic perovskite LEDs.

High-efficiency histamine-In-based halide phosphors with excellent thermal stability

<p indent=0mm>Metal halide perovskite semiconductors with attractive optoelectronic properties have potential applications in solar cells, light-emitting diodes (LEDs) and lasers. However, the toxicity and instability of Pb-based perovskites make them difficult to maintain long-term and uniform device performances in different environments (such as high temperature and humidity), hindering their further large-scale fabrication. These problems can be avoided by a reasonable design of novel low-dimensional lead-free metal halides (LLMHs). LLMHs with a low-dimensional structure provide a promising platform to achieve efficient broadband emission, especially considering their large exciton binding energy and strong electron-phonon coupling. In our recent studies, we have achieved efficient broadband emission in layered Na–In halide perovskites, demonstrating the feasibility of the Sb doping strategy. However, their thermal stability remains unsatisfactory, because their photoluminescence (PL) intensity decreases by 17.1%–43.5% after the heating-cooling cycle. For LLMHs, it is still a challenge to obtain broadband emission that combines high photoluminescence quantum efficiency (PLQE) and thermal stability. Hence, utilizing the Sb³⁺ doped LLMHs of (HA)₂KInCl₈–Sb (2D) and (HA)₂InCl₇·H₂O–Sb (0D) (HA²⁺=histamine) with PLQE of 58.8% and 63.4%, respectively. The van der Waals forces and hydrogen bonding of organic components can be enhanced by using HA²⁺ as A-site organic cations. By monitoring the fluorescence intensity during the heating-cooling cycles, we evaluated the thermal stability of two materials. They have excellent thermal stability and can maintain more than 95% PL intensity (relative to initial intensity) after the heating-cooling cycles, demonstrating the feasibility of this strategy.

Ultra-Confined Visible-Light-Emitting Colloidal Indium Arsenide Quantum Dots.

Indium arsenide quantum dots, which typically emit in the near-infrared, have been utilized in various optoelectronics and biomedical applications, such as covert illumination, optical communication, and deep-tissue imaging. While theory predicts that further quantum confinement through size reduction could enable visible light emission, systems with larger optical bandgaps have not been realized. Here, we report a method of preparing highly luminescent, visible-light-emitting In(Zn)As/ZnSe/ZnS QD, using a low-temperature nanocluster synthesis approach. Each QD contains an ultraconfined In(Zn)As nanocluster and fluoresces at tunable wavelengths between 538 and 640 nm with a high photoluminescence quantum efficiency of 58%. We confirm, through DFT and spectroscopic analysis, that the strong confinement effects in the few-atom-wide In(Zn)As nanoclusters are responsible for the significant spectral shift from the near-infrared to the visible region. These findings suggest that broader-than-expected optical tuning may now be achievable in other quantum-confined semiconductor systems, which could lead to a wider scope of functional applications in optoelectronics.

Crystallization Behavior and Luminescence of Inkjet Printing CH3NH3PbBr3

AbstractLead halide perovskites display remarkable optoelectronic properties, like large absorption coefficients, high photoluminescence quantum efficiencies, and long lifetime and diffusion length of photocarriers. This system is easily fabricated using solution processes and inkjet printing is an effective way to prepare halide perovskite films and complex patterns. In this work, the crystallization behaviors of inkjet printing CH3NH3PbBr3 crystals are systematically investigated with varied I− doping, printing times, and solvents. Using N,N‐dimethylformamide (DMF) solvent, CH3NH3PbBr3−xIx (x = 0, 0.14, 0.29, 0.45, 0.59) are printed on the glass and the crystalline grains are developed from the (001) oriented tetragonal in side length of 10–50 µm to dendrite with increasing I− concentrations. The crystalline grains are kept tetragonal, while the average crystal size changes from 22 to 89 µm by increasing the number of printing from 10 to 1000 times. DMF and dimethyl sulfoxide (DMSO) are used as solvents for printing CH3NH3PbBr3, and more regular grains are obtained from DMF solvent. Several patterns are printed on glass and papers, and fluorescent two‐dimensional (2D) patterns are observed under the 480 nm excitation. The as‐printed patterns show excellent homogeneity and high reproducibility, indicating that the inkjet printing shows broad application prospects in flexible electronics.

Intramolecular Through‐Space Charge Transfer Based TADF‐Active Multifunctional Emitters for High Efficiency Solution‐Processed OLED

AbstractThermally activated delayed fluorescence (TADF) has been explored actively in luminescent organic materials. Yet, realizing such TADF‐active, multifunctional emitters with high emission efficiency still remains hugely challenging. In this context, a series of twist‐conjugated organic molecules bearing diphenylsulfone and 9,9‐dimethylacridine moieties are designed and prepared, and are found to show, in one molecule, TADF, room‐temperature phosphorescence, triboluminescence, and aggregation‐induced emission enhancement. In addition, remarkably high photoluminescence quantum efficiency, up to ≈100%, is achieved for these novel molecules. Single‐crystal analysis and theoretical calculations reveal that the through‐space charge transfer (TSCT) effect in these molecules is responsible for both the multifunctional emission and high emission efficiency. A maximum external quantum efficiency of 20.1% is achieved, which is among the highest recorded in a solution‐processable device containing TSCT‐based TADF materials. These results illustrate a new approach to achieving highly efficient TADF‐active, multifunctional emitters.

Ultrabright and Highly Efficient All‐Inorganic Zero‐Dimensional Perovskite Scintillators

AbstractLow‐dimensional halide perovskites with excellent luminescent properties have become leading candidates for optoelectronic and radiation‐detection applications. In this work, Tl cation is incorporated into 0D perovskite Cs3Cu2I5 host and an ultrabright and efficient scintillator is developed for X‐ray and γ‐ray detection. The Tl‐doped Cs3Cu2I5 crystals exhibit a high photoluminescence quantum efficiency of 79.2%. The radioluminescence emission of Cs3Cu2I5:Tl crystal under X‐ray excitation consists of a self‐trapped exciton emission at 440 nm and a Tl‐related emission at 510 nm at room temperature. With optimized Tl doping, the Cs3Cu2I5 not only demonstrates about five‐times enhanced steady‐state scintillation yield up to 150 000 photons/MeV and an improvement of X‐ray detection limit from 103.6 to 66.3 nGy s−1, but also maintains an extremely low afterglow of 0.17% at 10 ms after X‐ray cut‐off. The Cs3Cu2I5:Tl also possess a remarkable energy resolution of 3.4% at 662 keV and an ultrahigh light yield of 87 000 photons/MeV under 137Cs γ‐ray radiation.

High-performance non-doped pure-blue electroluminescent device based on bisphenanthroimidazole derivative with twisted donor-acceptor structure

Abstract The development of efficient pure-blue emitters is of great significance for achieving high-quality display and lighting. Herein, a pure-blue emitter TPA-DPPI comprised of bisphenanthroimidazole and triphenylamine units with bipolar carrier transport property is designed and synthesized. For the two phenanthroimidazole units, one acts as the electron acceptor moiety, and the other is introduced to twist the molecule in order to suppress the intermolecular interactions in neat film. Highly twisted molecular configuration endows the compound with a high photoluminescence quantum efficiency yield of 0.56 in neat film. The non-doped device using TPA-DPPI as an emissive layer shows a pure-blue emission with a Commission International de l'Eclairage coordinates of (0.146, 0.097) and a high external quantum efficiency of 5.20%.

Multifunctional donor–acceptor conjugated polymers containing isoindigo and benzothiadiazole moieties for electrochromic, photoelectric sensor, 2,4,6-trinitrophenol detection and resistance memory device

Six novel donor–acceptor conjugated polymers were designed and synthesized by the Stille coupling reaction of triarylamine derivatives as donor units with isoindigo derivative or benzothiadiazole as acceptor units. These polymers have good solubility and film-forming properties in common organic solvents. The char yields of polymers in nitrogen atmosphere at 800 °C range from 34 to 60%. In particular, these conjugated polymers exhibit high photoluminescence (PL) quantum efficiency (up to 42.9%). These polymers demonstrate two pairs of redox peaks with low onset voltages (0.51 V vs. Ag/AgCl for P5) and narrow band gaps (Eg = 2.52 ~ 2.95 eV). The colors of all polymer films change significantly with the applied voltage increasing. Moreover, the polymers show high coloring efficiency (up to 163%) and maintain good electrochromic (EC) cycle stability over 500 s. In addition, excellent results in terms of memory storage (ON/OFF = 1.2 × 104), 2,4,6-Trinitrophenol (TNP) detection (Ksv = 45,790 M-1) can meet the requirements of multifunctional materials.

Improvement in color purity and lifetime of blue PHOLEDs using a homoleptic iridium(III) complex with fluorinated dibenzofuranyl-imidazole ligand

To improve the color purity and device lifetime of Ir(dbi)3, where dbi is [1-(2,4-diisopropyldibenzo[b,d]furan-3-yl)-2-phenyl-1H-imidazole), a new iridium(III) compound (1) bearing a fluorinated-dbi ligand was prepared via a one-pot reaction with moderate yield. Compound (1) exhibits distorted octahedral structure around the Ir(III) metal ion with a facial geometry and an inverted triangular shape with significant curvature based on Hirshfeld analysis. There are several intra and intermolecular interactions involving C-H⋯F/N/O hydrogen bonds, which impart high thermal and chemical stability to compound 1. Additionally, compound 1 exhibits bright blue emission (λmax = 460 nm) with high photoluminescent quantum efficiency of 0.5. Further, a remarkable decrease in the energy level of highest occupied molecular orbital (HOMO) is observed, while no significant change is observed in the energy level of lowest unoccupied molecular orbital (LUMO), which is attributed to the stronger electronegativity of fluorinated-dbi compared to the parent Ir(dbi)3 compound. Phosphorescent organic light-emitting diodes (PHOLEDs) were successfully fabricated using 3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) as the host, with 17.5% external quantum efficiency achieved. Moreover, the absolute device lifetime of the compound 1 based device at 10 wt% doping concentration is measured to be 47 h at 1000 cd/m2 luminance, which is much better than that of the parent Ir(dbi)3-based device. The introduction of fluorine atom to the molecular structure provides not only improved device lifetime via strong intermolecular interactions but also improved color purity.

Lead-Free Organic-Perovskite Hybrid Quantum Wells for Highly Stable Light-Emitting Diodes.

Two-dimensional perovskites that could be regarded as natural organic-inorganic hybrid quantum wells (HQWs) are promising for light-emitting diode (LED) applications. High photoluminescence quantum efficiencies (approaching 80%) and extremely narrow emission bandwidth (less than 20 nm) have been demonstrated in their single crystals; however, a reliable electrically driven LED device has not been realized owing to inefficient charge injection and extremely poor stability. Furthermore, the use of toxic lead raises concerns. Here, we report Sn(II)-based organic-perovskite HQWs employing molecularly tailored organic semiconducting barrier layers for efficient and stable LEDs. Utilizing femtosecond transient absorption spectroscopy, we demonstrate the energy transfer from organic barrier to inorganic perovskite emitter occurs faster than the intramolecular charge transfer in the organic layer. Consequently, this process allows efficient conversion of lower-energy emission associated with the organic layer into higher-energy emission from the perovskite layer. This greatly broadened the candidate pool for the organic layer. Incorporating a bulky small bandgap organic barrier in the HQW, charge transport is enhanced and ion migration is greatly suppressed. We demonstrate a HQW-LED device with pure red emission, a maximum luminance of 3466 cd m-2, a peak external quantum efficiency up to 3.33%, and an operational stability of over 150 h, which are significantly better than previously reported lead-free perovskite LEDs.

Singlet exciton fission in a modified acene with improved stability and high photoluminescence yield

We report a fully efficient singlet exciton fission material with high ambient chemical stability. 10,21-Bis(triisopropylsilylethynyl)tetrabenzo[a,c,l,n]pentacene (TTBP) combines an acene core with triphenylene wings that protect the formal pentacene from chemical degradation. The electronic energy levels position singlet exciton fission to be endothermic, similar to tetracene despite the triphenylenes. TTBP exhibits rapid early time singlet fission with quantitative yield of triplet pairs within 100 ps followed by thermally activated separation to free triplet excitons over 65 ns. TTBP exhibits high photoluminescence quantum efficiency, close to 100% when dilute and 20% for solid films, arising from triplet-triplet annihilation. In using such a system for exciton multiplication in a solar cell, maximum thermodynamic performance requires radiative decay of the triplet population, observed here as emission from the singlet formed by recombination of triplet pairs. Combining chemical stabilisation with efficient endothermic fission provides a promising avenue towards singlet fission materials for use in photovoltaics.

Advances on perovskite quantum dot electroluminescent devices

Perovskite materials display great potential in the optoelectronic applications and are considered as one of the most promising optoelectronic materials due to the advantages such as high color-rending index, wide color gamut, excellent charge-transport properties, adjustable band gap, high photoluminescence quantum efficiency, low manufacturing cost, and compatibility with flexible/stretchable devices. Applying perovskite QDs as phosphors in white light down-converted light- emitting diode (LED) or emitter materials in active matrix-QLEDs to obtain high efficiency and wide color gamut is significantly promising for next-generation high-definition information displays and high-quality lighting sources applications. In this paper, the evolution of device performance of perovskite QDs-based LEDs has been demonstrated. Significant enhancement of device performance has been realized through appropriate ligand choice and effective ligand exchange together with modifying device architectures. Meanwhile, numerous encouraging achievements have been achieved via inhibition of non-radiative recombination and enhancement of exciton binding energy, since the first perovskite LED was reported in 2014. Due to the quantum effect limited by space size, perovskite quantum dots have higher exciton binding energy, easily achievable high fluorescence quantum efficiency and narrow emission bandwidth. Because of the excellent photoelectric characteristics, perovskite quantum dots have a wide application potential in new display and solid state lighting. However, for the commercial applications, further efforts are required to elucidate the physical mechanisms and improve the device performance of perovskite QLEDs. Besides, the poor stability of perovskite QLEDs in ambient and harsh conditions has attracted a wide concern, and simultaneously, several strategies have been explored to circumvent this issue, including compositional engineering, surface engineering, matrix encapsulation and device encapsulation. Although significant advances have been made in this regard, the lifetime of perovskite QLEDs remains far away from the commercial requirements. Further strategies to stabilize perovskite QDs and prevent their decomposition are in demand. Encapsulation technology of such kind of devices should be further investigated. Moreover, to avoid the toxicity problem, stable lead-free metal halide analogues with high optoelectronic performance are also needed. Furthermore, colloidal perovskite QDs can maintain functionality under tensile strains, opening new possibilities for their applications in flexible/stretchable electronics to satisfy the future development trend of QLEDs. In recent years, perovskite quantum dots have become an important issue in the field of photoelectricity. The device performance of perovskite quantum dot light-emitting diode has advanced considerably. In this paper, the research progress of perovskite quantum dot electroluminescence devices is reviewed, the main factors restricting the electroluminescence performance of perovskite quantum dots are analyzed, and in view of the problems in devices: Poor charge transport caused by long-chain ligands, non-radiative quenching of excitons caused by surface defects, and imbalance of charge injection in devices, the improvement strategies are discussed separately. Due to the quantum effect limited by space size, perovskite quantum dots have higher exciton binding energy, easily achievable high fluorescence quantum efficiency and narrow emission bandwidth. Compared with perovskite orebody materials, perovskite quantum dots have greater application potential in the field of display and lighting. And we are convinced that a highly efficient and stable perovskite QDs-based LED will be fulfilled in the near future.

Lead chlorine cluster assembled one-dimensional halide with highly efficient broadband white-light emission.

One new type of hybrid lead halide of [DTHPE]2Pb3Cl10 has been synthesized and characterized containing a one-dimensional (1D) wavelike [Pb3Cl10]4- chain based on a corner-shared [Pb3Cl11] cluster. Remarkably, this cluster-based 1D chain displays intrinsic broadband white light emission with a high quantum efficiency of 19.45% exceeding those of previously reported typical two-dimensional perovskites.