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.     

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.     

Semiconducting properties of hydrothermally synthesized libethenite application to orange G photodegradation

The photo-electrochemical properties of the libethenite Cu₂(PO₄)(OH) were studied to assess the oxidation of orange G (OG) under both solar and artificial lights. The compound was synthesized by hydrothermal route and characterized by X-ray diffraction, scanning electron microscopy, thermal and chemical analyses, UV–vis diffuse reflectance and electrochemical impedance spectroscopy. The libethenite possesses an optical gap of 1.52 eV and exhibits n type semiconducting behavior with an activation energy of 20 meV. On the basis of photo-electrochemical properties, it was concluded that the conduction band of the material (=4.81 eV/+0.30 V_RHE) permits the formation of O₂^·− radicals for the OG oxidation. A maximum elimination of 94% was obtained upon sunlight within 120 min exposure. The injection process of orange G into the conduction band of the libethenite is confirmed by the photocurrent measurements at different concentrations. The decolorization process proceeds like a photo-Fenton reaction, based on copper ions. Referring to the energetic diagram, a degradation mechanism is proposed. Cu₂PO₄(OH) catalyst permits to activate H₂O₂ and initiate the decomposition of OG molecules. The OG removal follows a pseudo-first order kinetic with an apparent rate constant of 6.2×10⁻³ min⁻¹ under sunlight.     

Synthesis and semiconducting properties of Na2MnPO4F. Application to degradation of Rhodamine B under UV-light

Na₂MnPO₄F is synthesized by hydrothermal route at 453 K and the physical properties and photo-electrochemical characterizations are reported. The compound crystallizes in a monoclinic system (SG: P 2₁/n) with the lattice constants: a=13.7132 Å, b=5.3461 Å, c=13.7079 Å, β=119.97°. The UV–visible spectroscopy shows an indirect optical transition at 2.68 eV; a further direct transition occurs at 3.70 eV, due to the charge transfer O²⁻: 2p → Mn²⁺: e_g. The thermal variation of the electrical conductivity is characteristic of a semiconducting behavior with activation energy of 39 meV and an electron mobility (µ_318 K=5.56×10⁻⁴ cm² V⁻¹ s⁻¹), thermally activated. The flat band potential (+0.47 V_SCE) indicates that the valence band derives mainly from O²⁻: 2p orbital with a small admixture of F⁻ character while the conduction band is made up of Mn²⁺: t_2g orbital. The electrochemical impedance spectroscopy shows the contribution of both the bulk and grains boundaries. The photocatalytic performance of Na₂MnPO₄F for the degradation of Rhodamine B (RhB) is demonstrated on the basis of the energy diagram. 88% of the initial concentration is degraded under UV light and the oxidation follows a first order kinetic with a rate constant of 0.516 h⁻¹. Neither adsorption nor photolysis is observed. The photoactivity results from the electron transition from the hybridized band (O²⁻, F⁻) to the Mn²⁺: e_g orbital, occurring in the UV region. The catalyst was subjected to three successive photocatalytic cycles, thus proving its long term stability.     

Deposition of Fe3O4 on oxidized activated carbon by hydrazine reducing method for high performance supercapacitor

Oxidized activated carbon/Fe₃O₄ (AC/Fe₃O₄) composites for supercapacitor electrodes were synthesized by a reduction method. Poly(vinylpyrrolidone) was added as a dispersing agent for homogeneous deposition of Fe₃O₄ on AC. The obtained products were identified as AC/Fe₃O₄ by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Morphological characterization of AC/Fe₃O₄ was carried out by field emission scanning electron microscopy (FE-SEM); the results clearly showed the formation of Fe₃O₄ nanoparticles about 30 nm in diameter on AC. Moreover, by using N₂ adsorption/desorption isotherm analysis, we confirmed that surface areas and pore volumes decreased with increasing Fe₃O₄ content. We also carried out electrochemical characterization of AC and AC/Fe₃O₄ composites. Remarkably, we found that the value of specific capacitance increased significantly from 99.4 F g⁻¹ of raw AC to 202.6 F g⁻¹ of AC/Fe₃O₄ composites at 10 mV s⁻¹ of scan rate. This result can be ascribed to a synergistic effect of the combination of electrical double-layer capacitance and pseudo-capacitance properties. This research represents a valuable contribution to the application of supercapacitor electrodes in regard to cost effectiveness and simple fabrication.     

Preparation and physical properties of the layered niobate Cu0.5Nb3O8: Application to photocatalytic hydrogen evolution

The new layered niobate Cu_0.5Nb₃O₈ is synthesized by soft chemistry in aqueous electrolyte via Cu²⁺→H⁺ exchange between copper nitrate and HNb₃O₈·H₂O. The characterization of the exchanged product is made by means of thermal gravimetry, chemical analysis, X-ray diffraction and IR spectroscopy. Thermal analysis shows a conversion to anhydrous compound above 500 °C. The oxide displays a semiconductor like behavior; the thermal variation of the conductivity shows that d electrons are strongly localized and the conduction is thermally activated with activation energy of 0.13 eV. The temperature dependence of the thermopower is indicative of an extrinsic conductivity; the electrons are dominant carriers in conformity with an anodic photocurrent. Indeed, the Mott–Schottky plot confirms n-type conduction from which a flat band potential of −0.82 V_SCE, an electronic density of 8.72×10¹⁹ m⁻³ and a depletion width of 4.4 nm are determined. The upper valence band, located at ~5.8 eV below vacuum is made up predominantly of Cu²⁺: 3d with a small admixture of O²⁻: 2p orbitals whereas the conduction band consists of empty Nb⁵⁺: 5s level. The energy band diagram shows the feasibility of the oxide for the photocatalytic hydrogen production upon visible light (29 mW cm⁻²) with a rate evolution of 0.31 mL g⁻¹ min⁻¹.     

Preparation and characterization of the brownmillerite Sr2Co2O5 as novel photocatalyst in the hydrogen generation

Sr₂Co₂O₅ is a semiconductor belonging to the brownmillerite family; it is prepared by nitrate route and the photo-electrochemical properties are assessed for the first time for the photocatalytic hydrogen production. Thermal analysis indicates the formation of the semiconductor phase at 750 °C. An optical transition at 1.10 eV, directly allowed is obtained from the diffuse reflectance spectrum, due to the internal Co³⁺: d-d transition in octahedral coordination. A flat band potential of 0.037 V_SCE is determined in KOH solution (0.1 M) from the Mott-Schottky characteristic and the results are relevant for the water reduction. The conduction band of Sr₂Co₂O₅ (−0.85 V_SCE), deriving from Co³⁺: 3d orbital is more cathodic than the potential of H₂O/H₂ couple and hydrogen is successfully evolved under visible light. A rate evolution of 68 µmol (g catalyst)⁻¹ min⁻¹ at pH ∼ 12 and a light-to-chemical energy efficiency of 0.82% are determined.     

An oil-in-water self-assembly synthesis,characterization and photocatalytic properties of nano Ag@AgBr sensitized K2Ti4O9

Nano-sized plasmonic Ag@AgBr sensitized K₂Ti₄O₉ composite photocatalysts (hereafter designated as Ag@AgBr/K₂Ti₄O₉) was synthesized via a facile oil-in-water self-assembly method. The photocatalytic activity of the prepared materials for methylene blue (MB) degradation was examined under visible light irradiation. The results reveal that the size of Ag@AgBr, which evenly dispersed on the surface of K₂Ti₄O₉, distributes about 20 nm. The UV–vis diffuse reflectance spectra indicate that Ag@AgBr/K₂Ti₄O₉ samples have a significantly enhanced optical absorption in 420–800 nm. The photocatalytic activities of the Ag@AgBr/K₂Ti₄O₉ samples increase first and then decrease with increasing amount of loading Ag@AgBr and the Ag@AgBr(10 wt%)/K₂Ti₄O₉ sample exhibits the best photocatalytic activity and 95.75% MB was degraded after irradiation for 90 min. Additionally, studies performed using radical scavengers indicated that h⁺, ·OH and Br⁰ acted as the main reactive species.     

Growth behavior and improved water–vapor-permeation-barrier properties of 10-nm-thick single Al2O3 layer grown via cyclic chemical vapor deposition on organic light-emitting diodes

We have investigated the growth behavior and water vapor permeation barrier properties of cyclic chemical vapor deposition (C-CVD)-grown 10-nm-thick single layer of Al₂O₃. Al₂O₃ layers grown by C-CVD showed a high density of 3.298 g/cm³ and were amorphous without grain boundaries. A deposition rate of 0.46 nm/cycle was obtained. The C-CVD system was self-limiting, as in the case of atomic layer deposition, which enables precise control of the thickness of the Al₂O₃ layer. A water vapor transmission rate of 1.51 × 10⁻⁵ (g/m²)/day was obtained from a Ca degradation test performed at 85 °C and 85% relative humidity. Moreover, the performance of organic light-emitting diodes, passivated by a C-CVD-grown 10-nm-thick Al₂O₃ single layer, was not affected after 24,000 h of turn-on time; this is strong evidence that C-CVD-grown Al₂O₃ layers effectively prevent water vapor from diffusing into the active organic layer.     

Power factor improvement of delafossite CuAlO2 by liquid-phase sintering with Ag2O addition

Thermoelectric delafossite (CuAlO₂)_1−x(Ag₂O)_x with 0<x<0.06 is prepared at three different sintering temperatures, 1323 K, 1373 K, and 1473 K. The samples are obtained from a mixture of CuO, Al₂O₃, and additive Ag₂O powders. The mixture is ground and then pressed with uniaxial pressure into pellets. Differential scanning calorimetry and X-ray diffraction spectroscopy show that the sintering temperature to synthesize delafossite CuAlO₂ with Ag₂O addition is below 1473 K. X-ray diffraction patterns show the major phase of delafossite 3R-CuAlO₂ along with a trace amount of 2H-CuAlO₂. A small amount of the Ag phase is present in the samples depending on the amount of Ag₂O addition and sintering temperature. Energy dispersive spectroscopy and backscattered electron image analyses show that the Ag phase is segregated around the grain boundary. Liquid-phase sintering is used to explain the growth mechanism. The CuAlO₂ samples with Ag₂O addition obviously exhibit enhanced bulk density, grain size, and electrical conductivity. The highest power factor (PF), obtained by CuAlO₂ with 2 at% of Ag₂O sintered at 1373 K, is 8.23×10⁻⁵ W/(m K²) at 873 K. Hence, our findings show an improvement for delafossite CuAlO₂ by Ag₂O addition.     

Growth and characterization of indium oxide diodes prepared by reactive magnetron sputtering

The electrical properties of Cr/Pt/Au and Ni/Au ohmic contacts with unintentionally doped In₂O₃ (U-In₂O₃) film and zinc-doped In₂O₃ (In₂O₃:Zn) prepared by reactive magnetron sputtering deposition are described. The lowest specific contact resistance of Cr/Pt/Au and Ni/Au is 2.94 × 10⁻⁶ and 1.49 × 10⁻² Ω-cm², respectively, as determined by the transmission line model (TLM) after heat treatment at 300 °C by thermal annealing for 10 min in nitrogen ambient. The indium oxide diodes have an ideality factor of 1.1 and a soft breakdown voltage of 5 V. The reverse leakage current prior to breakdown is around 10⁻⁵ A.     

Sol–gel derived nanocrystalline TiO2 thin films: A promising candidate for self-cleaning smart window applications

In the present work, anatase TiO₂ films are prepared by sol–gel spin coating method. The structural and optical properties of the films have been studied at different post-annealing temperatures. The photocatalytic activity and electrochromic performance of the films are investigated. The films annealed at 400 °C exhibit the highest photocatalytic activity with a rate constant of 4.56×10⁻³ min⁻¹. The electrochromic performance for the films annealed at 400 °C expressed in terms of difference in optical density (ΔOD) at 550 nm between coloured and bleached state is 0.5493. This combination of photocatalysis and electrochromism makes the sol–gel derived titania thin films as promising candidates for self-cleaning smart window applications.     

Photocatalytic reduction of chromate oxyanions on MMnFe2O4 (M=Zn,Cd) nanoparticles

Spinel M_xMn_1−xFe₂O₄ ferrites (M=Zn or Cd) synthesized via the co-precipitation method were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV–vis and Mössbauer spectroscopy. MnFe₂O₄ exhibited mainly cubic structure when Cd was incorporated, whereas the Zn incorporation stimulated a mixed phase consisting of MnFe₂O₄ and ZnMnFe₂O₄. The IR spectra of both Cd- and Zn modified MnFe₂O₄ samples revealed vibration of the chemical bond Fe²⁺O²⁻ in A location of the tetrahedron which infers that dopants were uniformly distributed over the system. The optical band gap energy showed large variations; a smaller value was determined for Cd_0.2Mn_0.8Fe₂O₄ (1.46 eV) when compared with those of MnFe₂O₄ (2.16 eV) and Zn_0.2Mn_0.8Fe₂O₄ (2.8 eV). The analysis of Mössbauer spectra gave inversion values of Fe³⁺ distribution in tetrahedral coordinated sites of 24%, 57% and 65% in MnFe₂O₄, Zn_0.2Mn_0.8Fe₂O₄ and Cd_0.2Mn_0.8Fe₂O₄, respectively. It was found that Cd_0.2Mn_0.8Fe₂O₄ exhibited the best performance in the photocatalytic reduction of Cr(VI) to Cr(III) having a maximum value of 96% within 30 min, and the experimental data obeyed pseudo-second-order rate kinetic model. Also, the linear model of Langmuir attained a maximum adsorption capacity of 37 mg g⁻¹ for Cd_0.2Mn_0.8Fe₂O₄.     

Preparation and electrochemical capacitance of MnO2 thin films doped by CuBi2O4

Manganese dioxide (MnO₂) and CuBi₂O₄-doped MnO₂ thin films with different nanostructures were deposited on indium tin oxide (ITO) glass and Ti foil substrates by using a chemical bath deposition (CBD) technique. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron microscopy (XPS). The effects of doping and substrates on electrochemical properties of MnO₂ and CuBi₂O₄-doped MnO₂ thin films on ITO glass and Ti foil were investigated. Capacitive properties of MnO₂ and CuBi₂O₄-doped MnO₂ thin films electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 0.1 M Na₂SO₄ aqueous solution as electrolyte. Specific capacitance, obtained from electrochemical measurement for the CuBi₂O₄-doped MnO₂, exhibited a higher value of 338 F g⁻¹ compared to the MnO₂ exhibiting value of 135 F g⁻¹. In addition, CuBi₂O₄-doped MnO₂ thin films on an ITO electrode had a better and satisfactory specific capacitance value, and exhibited more excellent electrochemical stability and reversibility than Ti foil substrates.     

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.     

Zero-valent nanophase iron and nitrogen co-modified titania nanotube arrays: Synthesis,characterization, and enhanced visible-light photocatalytic performance

We prepared nano-zero-valent iron (nZVI) and N co-modified TiO₂ (nZVI/N–TiO₂) nanotube arrays as an enhanced visible-light photocatalyst. The TiO₂ nanotube arrays were synthesized by electrochemical anodization of Ti foil in a two-electrode system. Amorphous TiO₂ nanotube arrays were immersed in ammonia and then annealed to produce crystalline N-doped TiO₂ (N–TiO₂) nanotube arrays. nZVI spheres were directly deposited on the N–TiO₂ nanotube arrays by borohydride reduction. The photocatalysts were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and electrochemical impedance spectroscopy (EIS). The environmental applicability and photocatalytic activity of the proposed nZVI/N–TiO₂ nanotube arrays were tested by phenol degradation in an aqueous system under UV and visible light irradiation. The phenol degradation rate constants of each sample under visible light irradiation were in the following order: nZVI/N–TiO₂ (k_obs=0.006 min⁻¹⁾>N–TiO₂ (k_obs=0.002 min⁻¹) ⪢ nZVI/TiO₂ (k_obs=0.0003 min⁻¹)>TiO₂ (k_obs=0.0001 min⁻¹). This result can be attributed to the synergistic effect of the N–TiO₂ nanotubes with lower energy band gap and the electron transfer from the conduction band (CB) of N–TiO₂ to nZVI spheres highly-dispersed on the N–TiO₂ for enhanced separation of photogenerated electrons and holes.     

Effect of oxygen vacancy in tungsten oxide on the photocatalytic activity for decomposition of organic materials in the gas phase

The relationship between the oxygen vacancy of tungsten oxide and its ability to decompose organic materials under visible-light irradiation was investigated experimentally. In the field of rechargeable batteries, the highest charge-discharge rate is obtained when tungsten oxide is used as a negative electrode with an O/W ratio of 2.72. This result suggested that the number of oxygen vacancies in tungsten oxide affects the photocatalytic decomposition behavior of organic materials. Therefore, with the aim of increasing the photocatalytic activity of tungsten oxide to decompose organic materials, we attempted to clarify the role of the oxygen vacancy. WO_3 − x nanoparticles, including WO_2.83 and WO_2.72 nanoparticles, were fabricated by changing the annealing temperature in a 10% H₂, 90% N₂ atmosphere to generate different densities of oxygen vacancies. Tungsten oxide with O/W ratios of 2.83 and 2.72 exhibited no photocatalytic activity for the photodecomposition of organic materials. The maximum decomposition rate was obtained for stoichiometric WO₃ (O/W = 3). The reason for the decrease or disappearance of the photodecomposition ability should originate in the increase in the number of electrons generated by the oxygen vacancies. These excess electrons promote the recombination reaction between electrons and holes in WO_3 − x, and hence reduce the lifetime of electron-hole pairs.     

Synthesis and properties of Fe3O4/SiO2/TiO2 nanocomposites by hydrothermal synthetic method

Fe₃O₄/SiO₂/TiO₂ nanocomposites with well-defined core-shell structures were successfully prepared by a facile hydrothermal synthetic method for titania coating on Fe₃O₄/SiO₂ magnetic core. The as-prepared Fe₃O₄/SiO₂/TiO₂ composite particles were characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),Fourier transform infrared spectroscopy (FT-IR). The results showed that Fe₃O₄/SiO₂/TiO₂ was well crystallized at 140 °C with well-defined core-shell structures. Fe₃O₄/SiO₂/TiO₂ nanocomposites as well as pure TiO₂ showed good photocatalytic performance in the decolorization of methyl orange aqueous solution. Magnetic core coated by SiO₂ and TiO₂ layer still retained the good magnetic properties (Ms:3.04 emu g^-1) to facilitate catalyst recovery using external magnetic field.     

Synthesis and characterization of the semiconductor Li0.93Cu0.07Nb3O8: Application to oxygen evolution under visible light

The semiconductor Li_0.93Cu_0.07Nb₃O₈ is prepared by soft chemistry in aqueous electrolyte via Cu²⁺ → Li⁺ exchange between copper nitrate and LiNb₃O₈. The substituted niobate crystallizes in an orthorhombic symmetry and the semiconducting and photo-electrochemical properties are investigated for the first time. The oxide exhibits a dark brown color and the UV–Visible spectroscopy gives an optical gap of 1.42 eV, due to the crystal field splitting of Cu²⁺ in octahedral site. The thermal variation of the conductivity shows that Nb: 4d-electrons are localized and the data are fitted by a small-polaron hopping model σ = σ_o exp {−0.053 eV/kT} with a carrier density thermally activated. The capacitance measurement done in ionic electrolyte (Na₂SO₄, 10⁻² M) indicates n type semiconductor with mixed valences Nb^5+/4+, due to the hetero-valent substitution Li⁺/Cu²⁺, with a flat band potential of 0.28 V_SCE and electrons density of 2.17×10¹⁷ cm⁻³. The Nyquist diagram shows mainly the bulk contribution with a diffusion process. The valence band (6.39 eV below vacuum) derives from O^2-: 2p orbital with a small admixture of Cu²⁺: 3d character while the conduction band is made up of Nb⁵⁺: 4d orbital. The material is successfully tested for the oxygen generation with an evolution rate of 87 µmol mn⁻¹ g⁻¹ under visible light (29 mW cm⁻²) and a quantum yield of 0.35%.     

High-performance barrier using a dual-layer inorganic/organic hybrid thin-film encapsulation for organic light-emitting diodes

We report an inorganic/organic hybrid barrier that combines the alternating deposition of a layer of ZrO₂ using low temperature atomic layer deposition and a 16-μm-thick layer of UV-curable NOA63 epoxy using spin-coating. The effective water vapor transmission rates of single ZrO₂ film was improved by adding solution epoxy from 3.03 × 10⁻³ g/m² day to 1.27 × 10⁻⁴ g/m² day in the hybrid NOA63/ZrO₂/NOA63/ZrO₂ films at 20 °C and a relative humidity of 60%. In consequence, the organic light-emitting diodes encapsulated with inorganic/organic hybrid barriers were undamaged by environmental oxygen and moisture and their luminance decay time improved by a considerable extent.