Highly efficient visible-light driven AgBr/Ag3PO4 hybrid photocatalysts with enhanced photocatalytic activity

Highly efficient visible-light-driven AgBr/Ag₃PO₄ hybrid photocatalysts with different mole ratios of AgBr were prepared via an in-situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgBr/Ag₃PO₄ photocatalysts displayed the higher photocatalytic activity than pure Ag₃PO₄ and AgBr for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgBr/Ag₃PO₄ with 60% of AgBr exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgBr/Ag₃PO₄ readily transformed to be Ag@AgBr/Ag₃PO₄ system while the photocatalytic activity of AgBr/Ag₃PO₄ remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h⁺ and O₂^∙− play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgBr/Ag₃PO₄ hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag₃PO₄, Ag and AgBr, in which Ag nanoparticles act as the charge separation center.     

Regeneration of novel visible-light-driven Ag/Ag3PO4@C3N4 hybrid materials and their high photocatalytic stability

Novel visible-light-driven Ag₃PO₄@C₃N₄PO₄ loaded with metal Ag were synthesised via an anion-exchange precipitation method and regenerated by H₂O₂ and NaNH₃HPO₄. The obtained Ag/Ag₃PO₄@C₃N₄ and regenerated Ag/Ag₃PO₄@C₃N₄ were characterised by XRD, XPS, SEM and UV–vis. The XRD and UV–vis results revealed that the crystal structure and light adsorption property of Ag/Ag₃PO₄@C₃N₄ were similar to that of regenerated Ag/Ag₃PO₄@C₃N₄. The XPS result showed that the metallic Ag⁰ deposited on the surface of Ag/Ag₃PO₄@C₃N₄ and regenerated Ag/Ag₃PO₄@C₃N₄. The Ag/Ag₃PO₄@C₃N₄ hybrids displayed remarkable photocatalytic activity and stability after regeneration. Compared with pure Ag₃PO₄ or C₃N₄, the Ag/Ag₃PO₄@C₃N₄ and regenerated Ag/Ag₃PO₄@C₃N₄ enhancement in the photodegradation rate towards methyl orange is observed over under visible light irradiation. The enhanced photocatalytic performance was attributed to the synergistic effect between Ag₃PO₄ and C₃N₄ and a small amount of Ag⁰ which suppresses the charge recombination during photocatalytic process. This work could provide new insights into the fabrication of high stability visible photocatalysts and facilitate their practical application in environment issues.     

Highly efficient photocatalytic treatment of mixed dyes wastewater via visible-light-driven AgI–Ag3PO4/MWCNTs

A high-performance photocatalyst of AgI–Ag₃PO₄/multi-walled carbon nanotubes (MWCNTs) was fabricated by chemical precipitation method using KI, K₂HPO₄ and AgNO₃ in the presence of MWCNTs. Its structure and physical properties were characterized by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), UV–vis absorption spectra, X-ray photo-electron spectroscopy (XPS), photoluminescence spectra (PL) and photocurrent techniques. SEM, TEM and EDS analyses verified that AgI–Ag₃PO₄ is successfully loaded on MWCNTs. AgI–Ag₃PO₄/MWCNTs possess the absorption edge of red shift and small band gap energy, and could absorb more photons in the visible region. PL and photocurrent analyses illustrated that AgI–Ag₃PO₄/MWCNTs have the lowest emission peak intensity and the highest photoelectric current, compared with Ag₃PO₄, AgI and AgI–Ag₃PO₄. By using the photocatalytic degradation of mixed dyes wastewater of Orange II and ponceau 4R as a model reaction, the photocatalytic efficiencies of Ag₃PO₄, AgI, AgI–Ag₃PO₄ and AgI–Ag₃PO₄/MWCNTs were evaluated. The reaction results showed that AgI–Ag₃PO₄/MWCNTs have strong photocatalytic activity and excellent chemical stability in repeated and long-term applications. Therefore, the prepared AgI–Ag₃PO₄/MWCNTs could act as a high-performance catalyst for the photocatalytic degradation of mixed dyes wastewater and also suggested the promising applications.     

g-C3N4/Ag3PO4 composites with synergistic effect for increased photocatalytic activity under the visible light irradiation

The g-C₃N₄ was synthesized by a hydrothermal method and the g-C₃N₄/Ag₃PO₄ composites were prepared by a ordinary precipitation method. Microstructures, morphologies and optical properties of the as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the Ag₃PO₄ nanoparticles were dispersed on the surface of the flake-like g-C₃N₄, and the heterojunction was formed on the interface. The g-C₃N₄/Ag₃PO₄ (2 wt%) photocatalyst presented the highest photocatalytic activity for organic dye methylene blue (MB) degradation, and its photocurrent intensity was approximately 2 times than that of the pure Ag₃PO₄. The g-C₃N₄/Ag₃PO₄ (2 wt%) photocatalyst also exhibited photocatalytic performance in the decomposition of colorless antibiotic ciprofloxacin (CIP). The capture experiment confirmed that holes acted as the main active species during the photocatalytic reaction.     

Synthesis of micro-nano Ag3PO4/ZnFe2O4 with different organic additives and its enhanced photocatalytic activity under visible light irradiation

Several novel micro-nano Ag₃PO₄/ZnFe₂O₄ with excellent magnetic separation property and photocatalytic performance were successfully synthesized using different organic additives for the first time. In the composite, Ag₃PO₄ with flower-like, quadrangular prism and flake structures were obtained when the organic additive is hexadecyl trimethyl ammonium bromide (CTAB), sodium diethyldithiocarbamate (DDTC), or DL-malic acid (DLMA), respectively, while the ZnFe₂O₄ showed uniform spherical structure. From the results of the photocatalytic activity analysis, the Ag₃PO₄/ZnFe₂O₄ gained with the organic additive of DDTC showed the highest photocatalytic capability for 2, 4-dichlorophenol (2, 4-DCP) degradation under visible light irradiation compared with those of CTAB and DLMA as the additives. Moreover, the composition of the composite seriously influences the photocatalytic activity, and when the mass ratio of Ag₃PO₄ and ZnFe₂O₄ in the Ag₃PO₄/ZnFe₂O₄ (DITCH) is 9:1, the apparent photo degradation rate constant of 2, 4-DC is 0.0155 min⁻¹, which is 5.74 times of ZnFe₂O₄ (0.0027 min⁻¹) and 1.89 times of Ag₃PO₄ (0.0082 min⁻¹). Finally, the photocatalytic mechanism of Ag₃PO₄/ZnFe₂O₄ was discussed based on the heterojunction energy-band theory and Z-Scheme theory in detail.     

Influence of annealing temperature on visible-light photocatalytic activities of Ag3PO4 particulates synthesized using CH3COOAg as a precursor

Ag3PO4 microparticles (MPs) were prepared through a facile chemical precipitation route and using silver acetate (AgAc) as metal salt. The effect of annealing temperature (Ta) and time (τa) on the actual photocatalytic (PC) activity of Ag3PO4 MPs is investigated. The optimal annealing parameters are Ta of 400 °C and τa of 90 min. The enhanced PC activity by annealing at 400 °C is ascribed to the increase of electron mobility. Besides, an Ag3PO4 photoelectrode was fabricated through a drop-coating deposition route, which demonstrates a photocurrent density of 80 μA/cm2 and acceptable stability. The n-type conduction behavior of Ag3PO4 is verified by a Mott-Schottky (M-S) plot.     

Ag3PO4/BiPO4 p–n heterojunction nanocomposite prepared in room-temperature ionic liquid medium with improved photocatalytic activity

A visible-light-active Ag₃PO₄/BiPO₄ nanocomposite with a p–n heterojunction structure was fabricated via a co-precipitation hydrothermal process using 2-hydroxylethylammonium formate (RTIL) as a room-temperature ionic liquid. The resulting catalysts were characterized by various techniques. The photocatalytic activity of the photocatalysts was evaluated by the photodegradation of phthalocyanine Reactive Blue 21 (RB21) under both visible and UV light irradiations. The results reveal that the heterojunction composite prepared in RTIL noticeably exhibited an improvement in both efficiency and rate of RB21 photodegradation in comparison with pure Ag₃PO₄ and BiPO₄. The enhanced photocatalytic activity of Ag₃PO₄/BiPO₄ heterostructure prepared in RTIL is mainly ascribed to the internal electric field built at the heterojunction interface and efficient charge separation and transfer across the p–n junction. RTIL can also assist in decreasing the crystalline size, orderly distributing the particles, preventing the collapse of pore structures, and losing of composite surface area.     

Construction of Built‐In Electric Field within Silver Phosphate Photocatalyst for Enhanced Removal of Recalcitrant Organic Pollutants

Semiconductor photocatalysis technology has aroused great interest in photocatalytic degradation, but it suffers from the drawbacks of fast electron‐hole recombination and unsatisfactory degradation efficiency. Herein, a novel photocatalyst Ag₃PO₄@NC with excellent photocatalytic activity is successfully prepared, characterized, and evaluated for the efficient removal of organic pollutants. After visible light irradiation for 5, 8, and 12 min, the photocatalytic degradation efficiency of norfloxacin, diclofenac, and phenol on the composite catalyst reaches 100%, and the apparent rate constant of which is 19.2, 48.7, and 23.2 times than that of the pure Ag₃PO₄, respectively. The density functional theory calculation results indicate that there is a built‐in electric field from N‐doped carbon (NC) to Ag₃PO₄ at the interface of the composite catalyst. Driven by the electric field, the photogenerated electrons of Ag₃PO₄ can be readily transferred to the NC, leading to the efficient separation of photogenerated carriers and the significant improvement of the catalytic performance. The results of radical trapping experiments and electron spin resonance analysis show that photogenerated holes and O₂^? play an important role in the photodegradation process. This work provides a universal strategy of construction built‐in electric field through coupling with NC to improve the photocatalytic performance of photocatalysts.     

Ag3PO4(111)清洁面的原子弛豫对其体系能量及电子结构的影响

采用基于密度泛函理论的第一性原理GGA+U方法,研究了Ag3PO4(111)面的原子弛豫对其体系能量及电子结构的影响.发现Ag3PO4(111)面原子弛豫后,表面两个三配位的Ag原子均向里移动超过0.06 nm,而表面次层的O原子则均向外移动0.004 nm,导致弛豫后暴露在最表面的是O原子.而且弛豫使表面原子的核外电荷向表面内部发生了一定程度转移,表面键的杂化作用使共价左右增强,表面键长缩短.计算出的能带结构和态密度显示出原子弛豫窄化了价带宽度0.15 eV,增加了带隙宽度0.26 eV.同时未弛豫结构中存在于价带顶和导带底的两个表面峰在弛豫后完全消失,弛豫使Ag3PO4表面从金属特征向半导体特征转变.     

Optical and electrochemical gas sensing properties of yttrium–silver co-doped lithium iron phosphate thin films

The new sensing material, LiFe_0.995Y_0.0025Ag_0.0025PO₄ was synthesized using hydro-thermal methods, and characterized by X-ray diffraction, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. The as prepared products were subsequently utilized in a self assembled optical waveguide gases testing apparatus and a WS-30A electro-chemical gas sensing apparatus for xylene detection. A glass optical waveguide gas sensor was fabricated by spin-coating a LiFe_0.995Y_0.0025Ag_0.0025PO₄ thin film on the surface of single-mode tin-diffused glass Optical Waveguide. The sensing elements for electro-chemical gas sensor were made by dip-coating a LiFe_0.995Y_0.0025Ag_0.0025PO₄ thin film on the surface of an alumina ceramic tube, assembled with platinum wire. The experimental results indicated that, at room temperature, LiFe_0.995Y_0.0025Ag_0.0025PO₄ thin film/tin-diffused optical waveguide sensing element exhibited higher response to xylene in the range of 0.1–100 ppm; at an optimum operating temperature (300 °C), the response (S_r) of LiFe_0.995Y_0.0025Ag_0.0025PO₄ to 100 ppm of xylene was 5.29, as measured by the WS-30A electro-chemical gases sensing apparatus.     

Sensitized anti-stokes luminescence centers in AgCl crystals

In the AgCl microcrystals with adsorbed methylene blue dye molecules, sensitized anti-Stokes luminescence centers formed as a result of a photostimulated low-temperature (77 K) process are observed. The emission is recorded on excitation of the samples by radiation with the flux density 10¹⁴?10¹⁵ photon cm^?2 s^?1 in the spectral range 620–750 nm corresponding to optical absorption in the adsorbed dye molecules and adsorbed Ag₁, Ag₂, and Ag₃ clusters. It is shown that the anti-Stokes luminescence centers formed by photo-stimulation present (adsorbed dye molecule)—(silver subnanocluster) hybrid nanostructures, in which the bonding between the components is weak but sufficient to provide the possibility for two-photon interband transitions that occur due to transfer of the electron’s excitation energy from the dye molecule to the silver cluster with subsequent photoionization of the cluster.     

Photoelectric and luminescent properties of dysprosium-doped silver chloride

The influence of dysprosium doping on the photoelectric and luminescent properties of AgCl crystals is studied by methods of microwave photoconductivity and photoluminescence. Doping affects both the loss kinetics of photogenerated electrons and luminescence spectra and parameters of photostimulated burst of luminescence. It is shown that the charged [Dy_Ag^·· · V′_Ag]^· or neutral [Dy_Ag^·· · 2V′_Ag] ^x complexes are responsible for a new luminescence band peaked at 470 nm, which manifests itself at weight concentrations of the doping additive >10⁻⁶%. The long-wavelength shoulder at 570 nm in the photoluminescence spectra is attributed to intracenter transitions in the Dy³⁺ ions. The rate constant of the reaction of electron capture into the traps forming upon introduction of the dopant, k _t = (3–5) × 10⁻⁸ cm³ s⁻¹, is evaluated. It is assumed that the traps are Dy³⁺ dysprosium ions.     

Atomic Structure and Kinetics of NASICON NaxV2(PO4)3 Cathode for Sodium‐Ion Batteries

Na₃V₂(PO₄)₃ is one of the most important cathode materials for sodium‐ion batteries, delivering about two Na extraction/insertion from/into the unit structure. To understand the mechanism of sodium storage, a detailed structure of rhombohedral Na₃V₂(PO₄)₃ and its sodium extracted phase of NaV₂(PO₄)₃ are investigated at the atomic scale using a variety of advanced techniques. It is found that two different Na sites (6b, M1 and 18e, M2) with different coordination environments co‐exist in Na₃V₂(PO₄)₃, whereas only one Na site (6b, M1) exists in NaV₂(PO₄)₃. When Na is extracted from Na₃V₂(PO₄)₃ to form NaV₂(PO₄)₃, Na⁺ occupying the M2 site (CN = 8) is extracted and the rest of the Na remains at M1 site (CN = 6). In addition, the Na atoms are not randomly distributed, possibly with an ordered arrangement in M2 sites locally for Na₃V₂(PO₄)₃. Na⁺ ions at the M1 sites in Na₃V₂(PO₄)₃ tend to remain immobilized, suggesting a direct M2‐to‐M2 conduction pathway. Only Na occupying the M2 sites can be extracted, suggesting about two Na atoms able to be extracted from the Na₃V₂(PO₄)₃ structure.     

Imidazole‐Grafted Nanogels for the Fabrication of Organic–Inorganic Protein Hybrids

Here, a platform for the development of highly responsive organic–inorganic enzyme hybrids is provided. The approach entails a first step of protein engineering, in which individual enzymes are armored with a porous nanogel decorated with imidazole motifs. In a second step, by mimicking the biomineralization mechanism, the assembly of the imidazole nanogels with CuSO₄ and phosphate salts is triggered. A full characterization of the new composites reveals the first reported example in which the assembly mechanism is triggered by the sum of Cu(II)–imidazole interaction and Cu₃(PO₄)₂ inorganic salt formation. It is demonstrated that the organic component of the hybrids, namely the imidazole‐modified polyacrylamide hydrogel, provides a favorable spatial distribution for the enzyme. This results in enhanced conversion rates, robustness of the composite at low pH values, and a remarkable thermal stability at 65 °C, exhibiting 400% of the activity of the mineralized enzyme lacking the organic constituent. Importantly, unlike in previous works, the protocol applies to the use of a broad range of transition metal cations (including mono‐, di‐, and trivalent cations) to trigger the mineralization mechanism, which eventually broadens the chemical and structural diversity of organic–inorganic protein hybrids.     

Electrodeposited and characterization of Ag–Sn–S semiconductor thin films

Thin film of silver tin sulfides (Ag–Sn–S) has been deposited on indium tin oxide coated glass (ITO) substrates using potentiostatic cathodic electrodeposition technique. New procedure for the growth of Ag–Sn–S film is presented. An electrolyte solution containing Silver Nitrate (AgNO₃), Tin(II) Chloride (SnCl₂) and Sodium Thiosulfate (Na₂S₂O₃)in acidic solution (pH ~2) and at temperature of the bath 55 °C were used for the growth of Ag–Sn–S thin film. Prior to the deposition, a cyclic voltammetry technique was performed in binary (Ag–S, Sn–S) and ternary (Ag–Sn–S) systems. This study was carried out to examine the behavior of electroactive species at the electrode surface. Based on these results, the cathodic applied potential was fixed at −1000 mV versus Ag/AgCl to obtain a uniform and good adhesion of ternary thin film. After that, structural, morphological and optical performances of films have been investigated. The X-ray diffraction patterns of the samples demonstrate the presence of the orthorhombic phase of Ag₈SnS₆ at applied potential of −1000 mV versus Ag/AgCl. Based on the scanning electron microscopy (SEM), it was found that the surface morphology and grain size were strongly influenced by the presence of Sn and/or Ag in the electrolyte bath. The band gaps of binaries and ternary compound are evaluated from optical absorption measurements. Band gap of Ag₈SnS₆ determined from transmittance spectra is in the range 1.56 eV. Flat-band potential and free carrier concentration have been determined from Mott–Schottky plot and are estimated to be around 0.18 V and 2.21×10¹⁴ cm⁻³ respectively. The photoelectrochemical test of Ag₈SnS₆ was studied and the experimental observations are discussed in detail.     

Synthesis of CdIn2Se4 and Cu0.5Ag1.5InSe3 Compounds via Chemical and Solid-State Methods

CdIn₂Se₄ and Cu_0.5Ag_1.5InSe₃ are high-performance thermoelectric materials. In this study, both CdIn₂Se₄ and Cu_0.5Ag_1.5InSe₃ powders were synthesized using a microwave and solution method followed by annealing in nitrogen atmosphere. CdIn₂Se₄ was synthesized by two routes. First, CdSe was prepared using a microwave method. Second, In metal was prepared using a solution method. The prepared metals were annealed in nitrogen atmosphere. From the x-ray diffraction (XRD) results, CdIn₂Se₄ was observed as the main phase with CdSe and In₂O₃ as contaminant phases. The synthesis of Cu_0.5Ag_1.5InSe₃ was also divided into two steps. First, CuAg and Se were prepared using a microwave method. Second, In metal was prepared using a solution method. The prepared metals were annealed in nitrogen atmosphere. From the XRD results, Cu_0.5Ag_1.5InSe₃ was observed as the main phase with Cu_0.5?x Ag_1.5?y In _x+y Se and Se as contaminant phases.     

Effects of Ag addition and Ag3Sn formation on the mechanical reliability of Ni/Sn solder joints

Formation of intermetallic compounds (IMCs) in solder joints is closely associated with the mechanical reliability of the system. Though internal voids formed in Ni/Sn solder joints are known to be related to the formation of Ni₃Sn₄ IMC, a detailed study on the mechanical reliability has not yet been reported. In this study, the mechanical reliability of Ni/Sn joints was investigated using two different soldering systems: Ni/Ag-Ag/Sn/Ni bilayers and Ni/Sn/Ag-Ag/Sn/Ni sandwich structures. The failure mode was found to be closely related to the formation and growth of an Ag₃Sn phase. Filling of the voids with Ag₃Sn IMC resulted in maximum shear strength, with a failure locus through Ni₃Sn₄ and Ag₃Sn. However, formation of a large amount of Ag₃Sn decreased the shear strength once again.     

Structural and Optical Characterizations of Electrochemically Grown Connected and Free-Standing TiO2 Nanotube Array

A TiO₂ nanotube array was grown electrochemically by using single and mixed electrolyte/s with 20 V constant potential at room temperature. Anodization was carried out for 120 min using five different electrolytes, e.g., H₃PO₄, NH₄F, HF, NH₄F with H₃PO₄ and HF with H₃PO₄. Structural characterizations of the grown titania nanotubes were conducted by using x-ray diffraction and field emission scanning electron microscopy. Optical properties of the grown nanotubes were investigated through photoluminescence (PL) spectroscopy. In the case of the 4 M H₃PO₄ electrolyte, no perceptible growth of nanotubes was observed. The individual electrolytes of 0.3 M NH₄F and 1 M HF resulted into the formation of the wall-connected nanotubes. In contrast, the mixed electrolytes comprising the strong (NH₄F, HF) and weak (H₃PO₄) electrolytes have been found to be efficient for the growth of wall-separated titania nanotubes. The results of the PL spectroscopy have demonstrated that the free-standing nanotubes offer low PL intensity compared to its connected counterpart owing to the lower carrier recombination rate of free-standing nanotubes.     

Influence of microstructure on fatigue crack growth behavior of Sn-Ag solder interfaces

The relationship between microstructure and fatigue crack growth behavior was examined at Sn-Ag solder interfaces on copper and electroless-nickel metallizations. On copper metallization, the solder interface was lined with a coarse Ag₃Sn intermetallic phase in addition to the Cu₆Sn₅ intermetallic and the adjacent solder alloy contained nodular Ag₃Sn phase. This interfacial microstructure was shown to result in inferior fatigue resistance, with the fatigue crack path following the interfacial Ag₃Sn intermetallic phase. In contrast, the solder interface on the electroless-nickel metallization was covered with a thin layer of Ni₃Sn₄ intermetallic phase, and the solder microstructure was composed of fine needles of Ag₃Sn phase dispersed in the Sn-rich matrix. This solder interface was found to be significantly more resistant to fatigue than the copper/Sn-Ag solder interface.     

Phosphorescent Cationic Au4Ag2 Alkynyl Cluster Complexes for Efficient Solution‐Processed Organic Light‐Emitting Diodes

Cationic Au₄Ag₂ heterohexanuclear aromatic acetylides cluster complexes supported by bis(2‐diphenylphosphinoethyl)phenylphosphine (dpep) are prepared. The Au₄Ag₂ cluster structure originating from the combination of one anionic [Au(C≡CR)₂]^? with one cationic [Au₃Ag₂(dpep)₂(C≡CR)₂]³⁺ through the formation of Ag?acetylide η²‐bonds is highly stabilized by Au–Ag and Au–Au contacts. The Au₄Ag₂ alkynyl cluster complexes are moderately phosphorescent in the fluid CH₂Cl₂ solution, but exhibit highly intense phosphorescent emission in solid state and film. As revealed by theoretical computational studies, the phosphorescence is ascribable to significant ³[π (aromatic acetylide) → s/p (Au)] ³LMCT parentage with a noticeable Au₄Ag₂ cluster centered ³[d → s/p] triplet state. Taking advantage of mCP and OXD‐7 as a mixed host with 20 wt% dopant of phosphorescent Au₄Ag₂ cluster complex in the emitting layer, solution‐processed organic light‐emitting diodes (OLEDs) exhibit highly efficient electrophosphorescence with the maximum current, power, and external quantum efficiencies of 24.1 cd A^?1, 11.6 lm W^?1, and 7.0%, respectively. Introducing copper(I) thiocyanate (CuSCN) as a hole‐transporting layer onto the PEDOT:PSS hole‐injecting layer through the orthogonal solution process induces an obvious improvement of the device performance with lower turn‐on voltage and higher electroluminescent efficiency.