Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes(LEDs)due to their narrow emission linewidths,high photoluminescence quantum yields,a...Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes(LEDs)due to their narrow emission linewidths,high photoluminescence quantum yields,and tunable emission wavelengths.Achieving high-performance perovskite LEDs(Pe LEDs)requires the emissive layer to possess efficient radiative recombination,low defect density,minimal ion mobility,and effective carrier confinement.Perovskite/perovskite heterostructure(PPHS)offers a compelling approach for engineering emissive layers with these desired attributes,owing to their ability to passivate surface defects,tailor bandgaps,and suppress ion migration.Pe LEDs based on PPHS have demonstrated superior performance compared to single-phase devices,particularly in terms of external quantum efficiency and operational stability.This review provides a comprehensive overview of the typical PPHS architectures applied in Pe LEDs,including vertical,lateral,and bulk configurations.We discuss representative fabrication strategies and the associated optoelectronic properties of these heterostructures,highlighting the mechanisms by which they enhance device efficiency and stability.Finally,we explore the remaining challenges and prospects for the application of PPHS in Pe LEDs and other luminescent technologies.展开更多
Owing to the exceptional optoelectronic properties,metal halide perovskites have emerged as leading semiconductor materials for next-generation display technologies,providing perovskite light-emitting diodes(Pe LEDs)g...Owing to the exceptional optoelectronic properties,metal halide perovskites have emerged as leading semiconductor materials for next-generation display technologies,providing perovskite light-emitting diodes(Pe LEDs)great potential for high-quality color displays with a wide color gamut and pure color emission.Although laboratory-scale Pe LEDs have achieved neartheoretical efficiencies,challenges such as achieving uniform large-area films,improving material stability,and enhancing patterning precision remain barriers to commercialization.This review presents a systematic analysis of scalable manufacturing and precision patterning strategies for Pe LEDs,focusing on their applications in large-area lighting and full-color displays.Fabrication methods are categorized into film deposition techniques(spin-coating,blade-coating,and thermal evaporation)and patterning strategies,including top-down(photolithography,laser/e-beam lithography,and nanoimprinting)and bottom-up(patterned crystal growth,inkjet printing,and electrohydrodynamic jet printing)approaches.In this review,we discuss the advantages and limitations of each strategy,highlight current challenges,and outlook possible pathways towards scalable,high-performance Pe LEDs for advanced optoelectronic applications.展开更多
To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polym...To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.展开更多
Electrodeposited organic light-emitting diode(OLED)technology requires a spin-coating-free hole-injection layer that simultaneously provides smooth surface morphology,stable energy levels,and compatibility with high-r...Electrodeposited organic light-emitting diode(OLED)technology requires a spin-coating-free hole-injection layer that simultaneously provides smooth surface morphology,stable energy levels,and compatibility with high-resolution pixel architectures.In this study,electropolymerization of 3,4-ethylenedioxythiophene(EDOT)in poly(styrene sulfonate)(PSS-)surfactant-solubilized colloidal media is shown to afford poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)films with robust surface uniformity and stable energy levels suitable for application as hole-injection layers in OLEDs.Systematic investigation reveals that the hole-injection properties of these films are governed primarily by the colloidal chemistry of EDOT/PSS-surfactant-solubilized systems,rather than by conventional electrochemical parameters.This colloidal regulation modulates the film work function over a practically useful range.Incorporation of optimized films into OLEDs leads to enhanced hole injection and improved device performance,with external quantum efficiency increasing from 2.2%to 7.4%and minimal roll-off.Overall,this work demonstrates a feasible example of realizing spin-coating-free hole-injection layers,offering a potential direction for the development of electrodeposited injection layers for OLEDs.展开更多
Perovskite quantum dot light-emitting diodes(Pe-QLEDs)have shown immense application potential in display and lighting fields due to their narrow full-width at half maximum(FWHM)and high photoluminescence quantum yiel...Perovskite quantum dot light-emitting diodes(Pe-QLEDs)have shown immense application potential in display and lighting fields due to their narrow full-width at half maximum(FWHM)and high photoluminescence quantum yield(PLQY).Despite significant advancements in their performance,challenges such as defects and ion migration still hinder their long-term stability and operational efficiency.To address these issues,various optimization strategies,including ligand engineering,interface passivation,and self-assembly strategy,are being actively researched.This review focuses on the synthesis methods,challenges and optimization of perovskite quantum dots,which are critical for the commercialization and large-scale production of high-performance and stable Pe-QLEDs.展开更多
The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots(QDs),making them versatile building blocks for next-generation light-emitting diodes(LEDs).This study investiga...The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots(QDs),making them versatile building blocks for next-generation light-emitting diodes(LEDs).This study investigates how quantum confinement governs the charge transport,exciton dynamics,and emission efficiency in QD-LEDs,using CsPbI_(3) QDs as a model system.By systematically varying QD sizes,we reveal size-dependent trade-offs in LED performance,such as enhanced efficiency for smaller QDs but increased brightness and stability for larger QDs under high current densities.Our findings offer critical insights into the design of high-performance QD-LEDs,paving the way for scalable and energy-efficient optoelectronic devices.展开更多
Eco-friendly quantum-dot light-emitting diodes(QLEDs),which employ colloidal quantum dots(QDs)such as InP,and ZnSe,stand out due to their low toxicity,color purity,and high efficiency.Currently,significant advancement...Eco-friendly quantum-dot light-emitting diodes(QLEDs),which employ colloidal quantum dots(QDs)such as InP,and ZnSe,stand out due to their low toxicity,color purity,and high efficiency.Currently,significant advancements have been made in the performance of cadmium-free QLEDs.However,several challenges persist in the industrialization of ecofriendly QLED displays.For instance,(1)the poor performance,characterized by low photoluminescence quantum yield(PLQY),unstable ligand,and charge imbalance,cannot be effectively addressed with a solitary strategy;(2)the degradation mechanism,involving emission quenching,morphological inhomogeneity,and field-enhanced electron delocalization remains unclear;(3)the lack of techniques for color patterning,such as optical lithography and transfer printing.Herein,we undertake a specific review of all technological breakthroughs that endeavor to tackle the above challenges associated with cadmium-free QLED displays.We begin by reviewing the evolution,architecture,and operational characteristics of eco-friendly QLEDs,highlighting the photoelectric properties of QDs,carrier transport layer stability,and device lifetime.Subsequently,we focus our attention not only on the latest insights into device degradation mechanisms,particularly,but also on the remarkable technological progress in color patterning techniques.To conclude,we provide a synthesis of the promising prospects,current challenges,potential solutions,and emerging research trends for QLED displays.展开更多
A binary-mixed electron transport layer(ETL)has been reported for constructing solution-processable near-infrared organic light-emitting diodes(NIR OLEDs).Relative to the single-component ETL,the binarymixed ETL compo...A binary-mixed electron transport layer(ETL)has been reported for constructing solution-processable near-infrared organic light-emitting diodes(NIR OLEDs).Relative to the single-component ETL,the binarymixed ETL composed of PDINN:TPBi can enhance the carrier transport capacity,reduce device impedance,and weaken fiuorescence quenching of the emitting layer.By carefully selecting an appropriate luminescent material Y5(a nonfullerene electron acceptor in organic solar cells)and precisely fine-tuning the molecular aggregation in active layer using a mixed solvent,the morphology is optimized and luminescence performance is enhanced,resulting in efficient NIR OLEDs with an emission peak at 890 nm.The experiment showcases a Y5-based near-infrared OLED with a maximum radiance of 34.9 W sr^(-1)m^(-2)and a maximum external quantum efficiency of 0.50%,which is among the highest values reported for nondoped fiuorescent NIR OLEDs with an emission peak over 850 nm.展开更多
Triphenylamine(TPA)is the most promising donor fragment for the construction of long-wavelength thermally activated delayed fluorescence(TADF)emitters owing to its suitable dihedral angle that could enhance radiative ...Triphenylamine(TPA)is the most promising donor fragment for the construction of long-wavelength thermally activated delayed fluorescence(TADF)emitters owing to its suitable dihedral angle that could enhance radiative decay to compete with the serious non-radiative decay.However,the moderate electron-donating capacity of TPA seriously limits the selection of acceptor for constructing longwavelength TADF emitters with narrow bandgaps.To address this issue,in this work,the peripheral benzene of TPA was replaced with 1,4-benzodioxane and anisole to obtain two new electrondonating units N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-N-phenyl-2,3-dihydrobenzo[b][1,4]dioxin-6-amine(TPADBO,−5.02 eV)and 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline(TPAMO,−5.00 eV),which possess much shallower highest occupied molecule orbital(HOMO)energy levels than the prototype TPA(−5.33 eV).Based on TPA and the modified TPA donor fragments,three TADF emitters were designed and synthesized,namely Py-TPA,Py-TPADBO and Py-TPAMO,with the same acceptor fragment 12-(2,6-diisopropylphenyl)pyrido[2′,3′:5,6]pyrazino[2,3-f][1,10]phenanthroline(Py).Among them,Py-TPAMO exhibits the highest photoluminescence quantum yield of 78.4%and the smallest singlet-triplet energy gap,which is because the introduction of anisole does not cause significant molecule deformation for the excited Py-TPAMO.And Py-TPAMO-based OLEDs successfully realize a maximum external quantum efficiency of 25.5%with the emission peak at 605 nm.This work provides a series of candidate of donor fragments for the development of efficient long-wavelength TADF emitters.展开更多
Colloidal quantum dots(CQDs)are highly regarded for their outstanding photovoltaic characteristics,including excellent color purity,stability,high photoluminescence quantum yield(PLQY),narrow emission spectra,and ease...Colloidal quantum dots(CQDs)are highly regarded for their outstanding photovoltaic characteristics,including excellent color purity,stability,high photoluminescence quantum yield(PLQY),narrow emission spectra,and ease of solution processing.Despite significant progress in quantum dot light-emitting diodes(QLEDs)technology since its inception in 1994,blue QLEDs still fall short in efficiency and lifespan compared to red and green versions.The toxicity concerns associated with Cd/Pb-based quantum dots(QDs)have spurred the development of heavy-metal-free alternatives,such as groupⅡ−Ⅵ(e.g.,ZnSe-based QDs),groupⅢ−Ⅴ(e.g.,InP,GaN QDs),and carbon dots(CDs).In this review,we discuss the key properties and development history of quantum dots(QDs),various synthesis approaches,the role of surface ligands,and important considerations in developing core/shell(C/S)structured QDs.Additionally,we provide an outlook on the challenges and future directions for blue QLEDs.展开更多
With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><s...With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><span> </span><span>(50 μmol·m</span><sup><span style="vertical-align:super;">-2</span></sup><span>·s</span><sup><span style="vertical-align:super;">-1</span></sup><span>) including white LED light</span><span> </span><span>(WL), blue monochromatic light (B,</span><span> </span><span>465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the </span><span>stomata</span><span>l conductance (GS) of leaves, significantly improved the net photosynthetic rate</span><span> </span><span>(Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (P</span><sub><span style="vertical-align:sub;">max</span></sub><span>),</span><span> </span><span>apparent quantum efficiency</span><span> </span><span>(AQE) and light saturation point</span><span> </span><span>(LSP), and reduced the dark respiration rate (Rd) and light compensation point</span><span> </span><span>(LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that </span><i><span>Momordica charantia</span></i><span> is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.</span>展开更多
Given the central role of light in the algal photosynthesis,respiration,cell division,growth and the accumulation of value products,the effects of light-emitting diodes(LEDs)light wavelengths(blue,white,red and green)...Given the central role of light in the algal photosynthesis,respiration,cell division,growth and the accumulation of value products,the effects of light-emitting diodes(LEDs)light wavelengths(blue,white,red and green)were studied in Scenedesmus obliquus.Biomass,residual nutrient amount,soluble protein,astaxanthin and reactive oxygen species,superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)activity were analyzed to determine the effects of different monochromatic light wavelengths via biochemical methods.The results showed that blue light wavelength is the optimal light wavelength for phosphorus removal efficiency and the accumulation of biomass and astaxanthin in S.obliquus.Meanwhile,high reactive oxygen species content under the blue light might induce the accumulation of astaxanthin.The high activity of SOD,CAT and POD might participate in clearing the reactive oxygen species to facilitate the growth of microalgae.Furthermore,we found mixed blue/green lights treatment is the most appropriate mixture for the nitrogen removal.Under the blue light treatment,high light intensity and 18L:6D light cycle is the best condition for biomass and astaxanthin accumulation.Optimal nitrogen/phosphorus removal efficiency was observed under a 24L:0D light cycle.These results might provide a foundational data for the optimizing the productivity of high-value metabolites and treatment of wastewater.展开更多
Organic field-effect transistors(OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm^2V^(-1)s^(-1), demonstrating great potential for high-performance, l...Organic field-effect transistors(OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm^2V^(-1)s^(-1), demonstrating great potential for high-performance, low-cost organic electronic applications. However, fabrication of large-area organic micro-/nanocrystal arrays with consistent crystal growth direction has posed a significant technical challenge. Here, we describe a solution-processed dip-coating technique to grow large-area, aligned 9,10-bis(phenylethynyl) anthracene(BPEA) and 6,13-bis(triisopropylsilylethynyl) pentacene(TIPSPEN) single-crystalline nanoribbon arrays. The method is scalable to a 5 9 10 cm^2 wafer substrate, with around 60% of the wafer surface covered by aligned crystals. The quality of crystals can be easily controlled by tuning the dip-coating speed. Furthermore, OFETs based on well-aligned BPEA and TIPS-PEN single-crystalline nanoribbons were constructed.By optimizing channel lengths and using appropriate metallic electrodes, the BPEA and TIPS-PEN-based OFETs showed hole mobility exceeding 2.0 cm^2V^(-1)s^(-1)(average mobility 1.2 cm^2V^(-1)s^(-1)) and 3.0 cm^2V^(-1)s^(-1)(average mobility2.0 cm^2V^(-1)s^(-1)), respectively. They both have a high on/off ratio(I_(on)/I_(off))>10~9. The performance can well satisfy the requirements for light-emitting diodes driving.展开更多
A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and c...A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and carrier mobility of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode are numerically investigated.It is found that,for given values of the total thickness of organic layers,reduced depth of trap,total density of trap,and carrier mobility of HTL as well as EML,there exists an optimal thickness ratio of HTL to EML,by which a maximal quantum efficiency can be achieved.Through optimization of the thickness ratio,an enhancement of current density and quantum efficiency of as much as two orders of magnitude can be obtained.The dependences of the optimal thickness ratio to the characteristic trap energy,total density of trap and carrier mobility are numerically analyzed.展开更多
Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α...Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α' in Sr2SiO4:xEu^2+ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α' phase when x〉0.01. The emission spectrum of the β-Sr2SiO4:Eu^2+ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu^2+ phosphors were fabricated. The luminous efficiency (15.7lm/W) was higher than α'-Sr2SiO4:Eu^2+ phosphor white LED.展开更多
We report the fabrication and characterization of light-emitting diodes based on n-ZnO/p-GaN heterojunctions. The n-type ZnO epilayer is deposited by metalorganic chemical vapor deposition (MOCVD) on a MOCVD grown M...We report the fabrication and characterization of light-emitting diodes based on n-ZnO/p-GaN heterojunctions. The n-type ZnO epilayer is deposited by metalorganic chemical vapor deposition (MOCVD) on a MOCVD grown Mg-doped p-GaN layer to form a p-n heterojunction. During the etching process, the relation between the etching depth and the etching time is linear in a HF and NH4 CI solution of a certain ratio. The etching rates of the SiO2 and ZnO are well controlled,which are essential for device fabrication. The current-voltage relationship of this heterojunction shows a diode-like rectifying behavior. In contrast to previous reports,electroluminescence (EL) emissions are observed by the naked eye at room temperature from the n-ZnO/p-GaN heterojunction under forward-and reverse-bias. The origins of these EL emissions are discussed in comparison with the pho- toluminescence spectra.展开更多
The well crystalline YAG:Ce^3+ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce^3+ phosphor were investigated in the temperature range from...The well crystalline YAG:Ce^3+ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce^3+ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-repared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.展开更多
A mixed organic(4-phenylbutylamine, 4-PBA) and inorganic(cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as twodimensional per...A mixed organic(4-phenylbutylamine, 4-PBA) and inorganic(cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as twodimensional perovskites and high emission performance close to three-dimensional organic–inorganic hybrid perovskites. Light-emitting diodes(LEDs) are fabricated by using solution process based on the quasi-two-dimensional layered perovskites. The perovskite LEDs exhibit a sky-blue emission with electroluminescence peak at 491 nm and a low turn on voltage at 2.9 V. The maximum external quantum efficiency reaches 0.015% at brightness of 186 cd/m^2.展开更多
Metal halide perovskites have attracted tremendous interest due to their excellent optical and electrical properties,and they find many promising applications in the optoelectronic fields of solar cells,light-emitting...Metal halide perovskites have attracted tremendous interest due to their excellent optical and electrical properties,and they find many promising applications in the optoelectronic fields of solar cells,light-emitting diodes,and photodetectors.Thanks to the contributions of international researchers,significant progress has been made for perovskite light-emitting diodes(Pero-LEDs).The external quantum efficiencies(EQEs)of Pero-LEDs with emission of green,red,and near-infrared have all exceeded 20%.However,the blue Pero-LEDs still lag due to the poor film quality and deficient device structure.Herein,we summarize the strategies for preparing blue-emitting perovskites and categorize them into two:compositional engineering and size controlling of the emitting units.The advantages and disadvantages of both strategies are discussed,and a perspective of preparing high-performance blue-emitting perovskite is proposed.The challenges and future directions of blue PeroLEDs fabrication are also discussed.展开更多
Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel ...Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.展开更多
基金supported by the Advanced Talents Incubation Program of Hebei University(No.521100224235)the National Natural Science Foundation of China(No.52503363)the Natural Science Foundation of Hebei Province(No.E2025201009)。
文摘Metal halide perovskites have emerged as highly promising candidates for the emissive layer in next-generation light-emitting diodes(LEDs)due to their narrow emission linewidths,high photoluminescence quantum yields,and tunable emission wavelengths.Achieving high-performance perovskite LEDs(Pe LEDs)requires the emissive layer to possess efficient radiative recombination,low defect density,minimal ion mobility,and effective carrier confinement.Perovskite/perovskite heterostructure(PPHS)offers a compelling approach for engineering emissive layers with these desired attributes,owing to their ability to passivate surface defects,tailor bandgaps,and suppress ion migration.Pe LEDs based on PPHS have demonstrated superior performance compared to single-phase devices,particularly in terms of external quantum efficiency and operational stability.This review provides a comprehensive overview of the typical PPHS architectures applied in Pe LEDs,including vertical,lateral,and bulk configurations.We discuss representative fabrication strategies and the associated optoelectronic properties of these heterostructures,highlighting the mechanisms by which they enhance device efficiency and stability.Finally,we explore the remaining challenges and prospects for the application of PPHS in Pe LEDs and other luminescent technologies.
基金supported by 14th Five-Year Plan Key R&D Plan,Ministry of Science and Technology of the People’s Republic of China,2024YFB3409002National Natural Science Foundation of China,12302142+4 种基金HKUSTHKUST(GZ)Collaborative Research Scheme,G035Yangcheng Scholars Research Project-Leading Talent Training Project,2024312156Guangzhou-HKUST(GZ)Joint Funding Scheme,2023A03J0157Guangzhou Basic and Applied Basic Research Project,2024A04J4765Shenzhen Basic Research Project,JCYJ20220530114417040。
文摘Owing to the exceptional optoelectronic properties,metal halide perovskites have emerged as leading semiconductor materials for next-generation display technologies,providing perovskite light-emitting diodes(Pe LEDs)great potential for high-quality color displays with a wide color gamut and pure color emission.Although laboratory-scale Pe LEDs have achieved neartheoretical efficiencies,challenges such as achieving uniform large-area films,improving material stability,and enhancing patterning precision remain barriers to commercialization.This review presents a systematic analysis of scalable manufacturing and precision patterning strategies for Pe LEDs,focusing on their applications in large-area lighting and full-color displays.Fabrication methods are categorized into film deposition techniques(spin-coating,blade-coating,and thermal evaporation)and patterning strategies,including top-down(photolithography,laser/e-beam lithography,and nanoimprinting)and bottom-up(patterned crystal growth,inkjet printing,and electrohydrodynamic jet printing)approaches.In this review,we discuss the advantages and limitations of each strategy,highlight current challenges,and outlook possible pathways towards scalable,high-performance Pe LEDs for advanced optoelectronic applications.
基金the support from the Jiangsu Provincial Senior Talent Program (Dengfeng,Jiangsu University)the support from the National Key R&D Program of China (No.2024YFB3612600)+3 种基金the National Natural Science Foundation of China (Nos.22275098,62288102)Basic Research Program of Jiangsu (No.BK20243057)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (No.NY222097)the National Natural Science Foundation of China (No.62205035)。
文摘To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.
基金supported by the National Key R&D Program of China(No.2020YFA0714604)the Fund of Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates(No.2023B1212060003)+1 种基金the SSL Sci-tech Commissioner Program(No.20234383-01KCJ-G)the National Natural Science Foundation of China(No.92463310)。
文摘Electrodeposited organic light-emitting diode(OLED)technology requires a spin-coating-free hole-injection layer that simultaneously provides smooth surface morphology,stable energy levels,and compatibility with high-resolution pixel architectures.In this study,electropolymerization of 3,4-ethylenedioxythiophene(EDOT)in poly(styrene sulfonate)(PSS-)surfactant-solubilized colloidal media is shown to afford poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)films with robust surface uniformity and stable energy levels suitable for application as hole-injection layers in OLEDs.Systematic investigation reveals that the hole-injection properties of these films are governed primarily by the colloidal chemistry of EDOT/PSS-surfactant-solubilized systems,rather than by conventional electrochemical parameters.This colloidal regulation modulates the film work function over a practically useful range.Incorporation of optimized films into OLEDs leads to enhanced hole injection and improved device performance,with external quantum efficiency increasing from 2.2%to 7.4%and minimal roll-off.Overall,this work demonstrates a feasible example of realizing spin-coating-free hole-injection layers,offering a potential direction for the development of electrodeposited injection layers for OLEDs.
文摘Perovskite quantum dot light-emitting diodes(Pe-QLEDs)have shown immense application potential in display and lighting fields due to their narrow full-width at half maximum(FWHM)and high photoluminescence quantum yield(PLQY).Despite significant advancements in their performance,challenges such as defects and ion migration still hinder their long-term stability and operational efficiency.To address these issues,various optimization strategies,including ligand engineering,interface passivation,and self-assembly strategy,are being actively researched.This review focuses on the synthesis methods,challenges and optimization of perovskite quantum dots,which are critical for the commercialization and large-scale production of high-performance and stable Pe-QLEDs.
基金support from the National Key Research and Development Program of China(2024YFA1207700)National Natural Science Foundation of China(52072141,52102170).
文摘The quantum confinement effect fundamentally alters the optical and electronic properties of quantum dots(QDs),making them versatile building blocks for next-generation light-emitting diodes(LEDs).This study investigates how quantum confinement governs the charge transport,exciton dynamics,and emission efficiency in QD-LEDs,using CsPbI_(3) QDs as a model system.By systematically varying QD sizes,we reveal size-dependent trade-offs in LED performance,such as enhanced efficiency for smaller QDs but increased brightness and stability for larger QDs under high current densities.Our findings offer critical insights into the design of high-performance QD-LEDs,paving the way for scalable and energy-efficient optoelectronic devices.
基金supported by the Research Projects of Department of Education of Guangdong Province-024CJPT002Special Project of Guangdong Provincial Department of Education in Key Areas (No. 6021210075K)Shenzhen Polytechnic University Research Fund. (No. 6024310006K)
文摘Eco-friendly quantum-dot light-emitting diodes(QLEDs),which employ colloidal quantum dots(QDs)such as InP,and ZnSe,stand out due to their low toxicity,color purity,and high efficiency.Currently,significant advancements have been made in the performance of cadmium-free QLEDs.However,several challenges persist in the industrialization of ecofriendly QLED displays.For instance,(1)the poor performance,characterized by low photoluminescence quantum yield(PLQY),unstable ligand,and charge imbalance,cannot be effectively addressed with a solitary strategy;(2)the degradation mechanism,involving emission quenching,morphological inhomogeneity,and field-enhanced electron delocalization remains unclear;(3)the lack of techniques for color patterning,such as optical lithography and transfer printing.Herein,we undertake a specific review of all technological breakthroughs that endeavor to tackle the above challenges associated with cadmium-free QLED displays.We begin by reviewing the evolution,architecture,and operational characteristics of eco-friendly QLEDs,highlighting the photoelectric properties of QDs,carrier transport layer stability,and device lifetime.Subsequently,we focus our attention not only on the latest insights into device degradation mechanisms,particularly,but also on the remarkable technological progress in color patterning techniques.To conclude,we provide a synthesis of the promising prospects,current challenges,potential solutions,and emerging research trends for QLED displays.
基金supported by the National Natural Science Foundation of China(No.51973020)Beijing Natural Science Foundation(No.2232052)。
文摘A binary-mixed electron transport layer(ETL)has been reported for constructing solution-processable near-infrared organic light-emitting diodes(NIR OLEDs).Relative to the single-component ETL,the binarymixed ETL composed of PDINN:TPBi can enhance the carrier transport capacity,reduce device impedance,and weaken fiuorescence quenching of the emitting layer.By carefully selecting an appropriate luminescent material Y5(a nonfullerene electron acceptor in organic solar cells)and precisely fine-tuning the molecular aggregation in active layer using a mixed solvent,the morphology is optimized and luminescence performance is enhanced,resulting in efficient NIR OLEDs with an emission peak at 890 nm.The experiment showcases a Y5-based near-infrared OLED with a maximum radiance of 34.9 W sr^(-1)m^(-2)and a maximum external quantum efficiency of 0.50%,which is among the highest values reported for nondoped fiuorescent NIR OLEDs with an emission peak over 850 nm.
基金supported by the National Natural Science Foundation of China (Nos. 62222503, 52073040 and 52130304)the Sichuan Science and Technology Program (Nos. 2024NSFSC0012,2023NSFSC1973 and 2024NSFSC1446)+2 种基金the China Postdoctoral Science Foundation (Nos. 2023M740504 and GZC20230380)the Sichuan Provincial Human Resources and Social Security Department Programthe Collaborative Innovation Center of Suzhou Nano Science&Technology
文摘Triphenylamine(TPA)is the most promising donor fragment for the construction of long-wavelength thermally activated delayed fluorescence(TADF)emitters owing to its suitable dihedral angle that could enhance radiative decay to compete with the serious non-radiative decay.However,the moderate electron-donating capacity of TPA seriously limits the selection of acceptor for constructing longwavelength TADF emitters with narrow bandgaps.To address this issue,in this work,the peripheral benzene of TPA was replaced with 1,4-benzodioxane and anisole to obtain two new electrondonating units N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-N-phenyl-2,3-dihydrobenzo[b][1,4]dioxin-6-amine(TPADBO,−5.02 eV)and 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline(TPAMO,−5.00 eV),which possess much shallower highest occupied molecule orbital(HOMO)energy levels than the prototype TPA(−5.33 eV).Based on TPA and the modified TPA donor fragments,three TADF emitters were designed and synthesized,namely Py-TPA,Py-TPADBO and Py-TPAMO,with the same acceptor fragment 12-(2,6-diisopropylphenyl)pyrido[2′,3′:5,6]pyrazino[2,3-f][1,10]phenanthroline(Py).Among them,Py-TPAMO exhibits the highest photoluminescence quantum yield of 78.4%and the smallest singlet-triplet energy gap,which is because the introduction of anisole does not cause significant molecule deformation for the excited Py-TPAMO.And Py-TPAMO-based OLEDs successfully realize a maximum external quantum efficiency of 25.5%with the emission peak at 605 nm.This work provides a series of candidate of donor fragments for the development of efficient long-wavelength TADF emitters.
基金supported by the National Key Research and Development Program of China(2024YFE0103600)the National Natural Science Foundation of China(NSFC)(62474119,62205230,and 62175171)Suzhou Key Laboratory of Functional Nano&Soft Materials,Collaborative Innovation Center of Suzhou Nano Science&Technology,the 111 Project,Joint International Research Laboratory of Carbon-Based Functional Materials and Devices.
文摘Colloidal quantum dots(CQDs)are highly regarded for their outstanding photovoltaic characteristics,including excellent color purity,stability,high photoluminescence quantum yield(PLQY),narrow emission spectra,and ease of solution processing.Despite significant progress in quantum dot light-emitting diodes(QLEDs)technology since its inception in 1994,blue QLEDs still fall short in efficiency and lifespan compared to red and green versions.The toxicity concerns associated with Cd/Pb-based quantum dots(QDs)have spurred the development of heavy-metal-free alternatives,such as groupⅡ−Ⅵ(e.g.,ZnSe-based QDs),groupⅢ−Ⅴ(e.g.,InP,GaN QDs),and carbon dots(CDs).In this review,we discuss the key properties and development history of quantum dots(QDs),various synthesis approaches,the role of surface ligands,and important considerations in developing core/shell(C/S)structured QDs.Additionally,we provide an outlook on the challenges and future directions for blue QLEDs.
文摘With andromonoecious<i><span> Momordica charantia </span></i><span>L.</span><span> </span><span>(bitter gourd) as material, three light qualities</span><span> </span><span>(50 μmol·m</span><sup><span style="vertical-align:super;">-2</span></sup><span>·s</span><sup><span style="vertical-align:super;">-1</span></sup><span>) including white LED light</span><span> </span><span>(WL), blue monochromatic light (B,</span><span> </span><span>465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the </span><span>stomata</span><span>l conductance (GS) of leaves, significantly improved the net photosynthetic rate</span><span> </span><span>(Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (P</span><sub><span style="vertical-align:sub;">max</span></sub><span>),</span><span> </span><span>apparent quantum efficiency</span><span> </span><span>(AQE) and light saturation point</span><span> </span><span>(LSP), and reduced the dark respiration rate (Rd) and light compensation point</span><span> </span><span>(LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that </span><i><span>Momordica charantia</span></i><span> is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.</span>
基金This research was supported by National Natural Science Foundation of China(41806168)Agriculture Research System of China(CARS-50)+2 种基金Start-Up funding of Shantou University(NTF18004)Department of Education of Guangdong Province(2017KQNCX076)International cooperation research project of Shantou University(NC2017001).
文摘Given the central role of light in the algal photosynthesis,respiration,cell division,growth and the accumulation of value products,the effects of light-emitting diodes(LEDs)light wavelengths(blue,white,red and green)were studied in Scenedesmus obliquus.Biomass,residual nutrient amount,soluble protein,astaxanthin and reactive oxygen species,superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)activity were analyzed to determine the effects of different monochromatic light wavelengths via biochemical methods.The results showed that blue light wavelength is the optimal light wavelength for phosphorus removal efficiency and the accumulation of biomass and astaxanthin in S.obliquus.Meanwhile,high reactive oxygen species content under the blue light might induce the accumulation of astaxanthin.The high activity of SOD,CAT and POD might participate in clearing the reactive oxygen species to facilitate the growth of microalgae.Furthermore,we found mixed blue/green lights treatment is the most appropriate mixture for the nitrogen removal.Under the blue light treatment,high light intensity and 18L:6D light cycle is the best condition for biomass and astaxanthin accumulation.Optimal nitrogen/phosphorus removal efficiency was observed under a 24L:0D light cycle.These results might provide a foundational data for the optimizing the productivity of high-value metabolites and treatment of wastewater.
基金supported by the National Basic Research Program of China(2013CB933500)National Natural Science Foundation of China(Grant Nos.61422403,51672180,51622306,21673151)+2 种基金Qing Lan ProjectCollaborative Innovation Center of Suzhou Nano Science and Technology(NANO-CIC)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Organic field-effect transistors(OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm^2V^(-1)s^(-1), demonstrating great potential for high-performance, low-cost organic electronic applications. However, fabrication of large-area organic micro-/nanocrystal arrays with consistent crystal growth direction has posed a significant technical challenge. Here, we describe a solution-processed dip-coating technique to grow large-area, aligned 9,10-bis(phenylethynyl) anthracene(BPEA) and 6,13-bis(triisopropylsilylethynyl) pentacene(TIPSPEN) single-crystalline nanoribbon arrays. The method is scalable to a 5 9 10 cm^2 wafer substrate, with around 60% of the wafer surface covered by aligned crystals. The quality of crystals can be easily controlled by tuning the dip-coating speed. Furthermore, OFETs based on well-aligned BPEA and TIPS-PEN single-crystalline nanoribbons were constructed.By optimizing channel lengths and using appropriate metallic electrodes, the BPEA and TIPS-PEN-based OFETs showed hole mobility exceeding 2.0 cm^2V^(-1)s^(-1)(average mobility 1.2 cm^2V^(-1)s^(-1)) and 3.0 cm^2V^(-1)s^(-1)(average mobility2.0 cm^2V^(-1)s^(-1)), respectively. They both have a high on/off ratio(I_(on)/I_(off))>10~9. The performance can well satisfy the requirements for light-emitting diodes driving.
文摘A numerical model for bilayer organic light-emitting diodes (OLEDs) is developed under the basis of trapped charge limited conduction.The dependences of the current density on the layer thickness,trap properties and carrier mobility of the hole transport layer (HTL) and emission layer (EML) in bilayer OLEDs of the structure anode/HTL/EML/cathode are numerically investigated.It is found that,for given values of the total thickness of organic layers,reduced depth of trap,total density of trap,and carrier mobility of HTL as well as EML,there exists an optimal thickness ratio of HTL to EML,by which a maximal quantum efficiency can be achieved.Through optimization of the thickness ratio,an enhancement of current density and quantum efficiency of as much as two orders of magnitude can be obtained.The dependences of the optimal thickness ratio to the characteristic trap energy,total density of trap and carrier mobility are numerically analyzed.
基金the Ministry of Science and Technology (MOST) of China (2006AA03A138)the National Natural Science Foundation of China (10774141, 10574128)
文摘Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α' in Sr2SiO4:xEu^2+ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α' phase when x〉0.01. The emission spectrum of the β-Sr2SiO4:Eu^2+ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu^2+ phosphors were fabricated. The luminous efficiency (15.7lm/W) was higher than α'-Sr2SiO4:Eu^2+ phosphor white LED.
文摘We report the fabrication and characterization of light-emitting diodes based on n-ZnO/p-GaN heterojunctions. The n-type ZnO epilayer is deposited by metalorganic chemical vapor deposition (MOCVD) on a MOCVD grown Mg-doped p-GaN layer to form a p-n heterojunction. During the etching process, the relation between the etching depth and the etching time is linear in a HF and NH4 CI solution of a certain ratio. The etching rates of the SiO2 and ZnO are well controlled,which are essential for device fabrication. The current-voltage relationship of this heterojunction shows a diode-like rectifying behavior. In contrast to previous reports,electroluminescence (EL) emissions are observed by the naked eye at room temperature from the n-ZnO/p-GaN heterojunction under forward-and reverse-bias. The origins of these EL emissions are discussed in comparison with the pho- toluminescence spectra.
基金the Key Technologies R&D Program of Shandong Province (2006gg2201014)Tianjin Natural Science Foundation (07JCYBJC06400)Tianjin Education Committee Science and Technology Development Foundation
文摘The well crystalline YAG:Ce^3+ phosphor was synthesized by sold-state method, and the temperature dependence of excitation and emission spectra of YAG:Ce^3+ phosphor were investigated in the temperature range from room temperature to 573 K. With temperature increasing, it was noted that the emission intensity of as-repared phosphors decreased considerably more rapidly when pumped by 460 nm than by 340 nm. The temperature-intensity curves under different excitation wavelengths were obtained using an Arrhenius function, and the corresponding activation energies were also obtained respectively. Thus, the experimental phenomenon was discussed in terms of nonradiative decay rate. The effects of as-prepared phosphors on the performance of the white LED with changing temperature were also studied.
基金financially supported by the National Basic Research Program of China-Fundamental Studies of Perovskite Solar Cells (No. 2015CB932200)the Natural Science Foundation of [6_TD$IF]Jiangsu Province, China (Nos. BK20131413, BK20140952, BM2012010)+3 种基金the National Natural Science Foundation of China (Nos. 11474164, 61405091)the National 973 Program of China (No. 2015CB654901)the Jiangsu Specially-Appointed Professor programthe Synergetic Innovation Center for Organic Electronics and Information Displays
文摘A mixed organic(4-phenylbutylamine, 4-PBA) and inorganic(cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as twodimensional perovskites and high emission performance close to three-dimensional organic–inorganic hybrid perovskites. Light-emitting diodes(LEDs) are fabricated by using solution process based on the quasi-two-dimensional layered perovskites. The perovskite LEDs exhibit a sky-blue emission with electroluminescence peak at 491 nm and a low turn on voltage at 2.9 V. The maximum external quantum efficiency reaches 0.015% at brightness of 186 cd/m^2.
基金supported by the National Natural Science Foundation of China(Nos.51802102,21805101 and 51902110).
文摘Metal halide perovskites have attracted tremendous interest due to their excellent optical and electrical properties,and they find many promising applications in the optoelectronic fields of solar cells,light-emitting diodes,and photodetectors.Thanks to the contributions of international researchers,significant progress has been made for perovskite light-emitting diodes(Pero-LEDs).The external quantum efficiencies(EQEs)of Pero-LEDs with emission of green,red,and near-infrared have all exceeded 20%.However,the blue Pero-LEDs still lag due to the poor film quality and deficient device structure.Herein,we summarize the strategies for preparing blue-emitting perovskites and categorize them into two:compositional engineering and size controlling of the emitting units.The advantages and disadvantages of both strategies are discussed,and a perspective of preparing high-performance blue-emitting perovskite is proposed.The challenges and future directions of blue PeroLEDs fabrication are also discussed.
基金supported by the National Key R&D Program of China(2016YFB070700702)the National Natural Science Foundation of China(51761145048)+1 种基金the Fundamental Research Funds for the Central Universities(HUST:2019421JYCXJJ004)the China Postdoctoral Science Foundation Grant(2019M662624).
文摘Light-emitting diodes based on lead halide perovskite have attracted great attention due to their outstanding performance.However,their application is plagued by the toxicity of Pb and the poor stability.Herein novel copper-based all inorganic perovskite CsCu2I3 with much enhanced stability has been reported with a potential photoluminescence quantum yield(PLQY)over 20%and self-trapped excitons(STE).By taking advantage of its extraordinary thermal stability,we successfully fabricate high-quality CsCu2I3 film through direct vacuum-based deposition(VBD)of CsCu2I3 powder.The resulting film shows almost the same PLQY with the synthesized powder,as well as excellent uniformity and stability.The perovskite light-emitting diodes(Pe-LED)based on the evaporated CsCu2I3 emitting layer achieve a luminescence of 10 cd/m2 and an external quantum efficiency(EQE)of 0.02%.To the best of our knowledge,this is the first CsCu2I3 Pe-LED fabricated by VBD with STE property,which offers a new avenue for lead-free Pe-LED.