213 results about "Electron hole recombination" patented technology

Disclosed is an electroluminescent device having a cathode and an anode, an organic light emitting layer (LEL) containing at least one organic host material and a light emitting first dopant, and a layer containing a stabilizing second dopant wherein: a) the organic host material is capable of sustaining both hole and electron injection and recombination of electrons and holes; and b) the first dopant is a green light emitting organic material capable of accepting energy from the electron-hole recombination in the host material and of accepting energy transferred from the second dopant and is selected to have a bandgap energy lower than or equal to the bandgap energy of the second dopant material; c) the second dopant is a stabilizing material capable of accepting energy of electron-hole recombination in the host material, the second dopant being selected to have a bandgap energy lower than the bandgap energy of the host material, but higher or equal to the first dopant; wherein emissions from the first dopant and emissions from the second dopant, if any, have a peak emission in the OLED device less than 570 nm.

A system for disinfecting a fluid containing microorganisms or chemical contaminants includes a plurality of photocatalyst surfaces secured to a solid surface upon which a fluid to be disinfected contacts. A structure for removing a portion of the photogenerated electrons is in electrical contact with the photocatalyst layer, wherein an electron-hole recombination rate involving the photogenerated electrons and holes is reduced, thus increasing the removal rate of microorganisms or chemical contaminants from the fluid. The system can include a source of photons having a wavelength corresponding to a band gap energy of the photocatalyst to illuminate the photocatalyst layer. The invention can be used in air supply registers of a heating, ventilating and air conditioning system, or in air ducts, or used to disinfect wall coverings, floor coverings, envelopes, packages, and clothing articles.

Structures and methodologies to obtain lasing in indirect gap semiconductors such as Ge and Si are provided and involves excitonic transitions in the active layer comprising of at least one indirect gap layer. Excitonic density is increased at a given injection current level by increasing their binding energy by the use of quantum wells, wires, and dots with and without strain. Excitons are formed by holes and electrons in two different layers that are either adjacent or separated by a thin barrier layer, where at least one layer confining electrons and holes is comprised of indirect gap semiconductor such as Si and Ge, resulting in high optical gain and lasing using optical and electrical injection pumping. In other embodiment, structures are described where excitons formed in an active layer confining electrons in the direct gap layer and holes in the indirect gap layer; where layers are adjacent or separated by a thin barrier layer. The carrier injection structures are configured as p-n junctions and metal-oxide-semiconductor (MOS) field-effect transistors. The optical cavity is realized to confine photons. In the case of MOS structures, electrons from the inversion layer, formed under the gate at voltages above threshold, are injected into one or more layers comprising of quantum wells (2-d), quantum wires (1-d) and quantum dots (0-d) structures. The confinement of photons emitted upon electron-hole recombination produces lasing in active layer comprising of dots / wells. Bipolar transistor structures can also be configured as lasers.

Provided is a solar cell including: a first electrode and a second electrode facing each other; a porous membrane interposed between the first electrode and the second electrode and having a dye adsorbed thereto; an electrolyte interposed between the first electrode and the second electrode; and a buffering layer interposed between the first electrode and the porous membrane and having at least two layers. According to the construction of the solar cell, an electron-hole recombination is prevented by preventing the contact between an electrode having a porous membrane and an electrolyte, thereby improving the electron collection property and the photoelectric conversion efficiency of the dye-sensitized solar cell.

Thin film for optical applications, light-emitting structure using the same and the fabrication method thereof are disclosed. The present invention provides a silica or silica-related thin film for optical applications in which silicon nanoclusters and rare earth elements are co-doped. The average size of the silicon nanoclusters is less than 3 nm and the concentration of the rare earth elements is less than 0.1 atomic %. The ratio of the rare earth element concentration to that of silicon nanoclusters is controlled to range from 1 to 10 in the thin film. The thin film emits light by exciting the rare earth elements through electron-hole recombinations in the silicon nanoclusters. According to the present invention, the conditions such as the size and concentration of the silicon nanoclusters, the concentration of the rare earth element, and their concentration ratio are specifically optimized to fabricate optical devices with better performance.

The invention provides a near-ultraviolet LED lamp with a novel electron blocking layer, and a preparation method thereof. A near-ultraviolet LED epitaxial wafer structure comprises a graphical sapphire substrate, a low-temperature GaN nucleating layer, a high-temperature non-doped GaN buffer layer, an n-type GaN layer, an InGaN / AlGaN multiple-quantum well active layer, a p-type AlGaN / InGaN superlattice electron blocking layer, a low-temperature lightly-doped p-type AlInGaN hole expansion layer, a high-temperature p-type GaN layer and a p-type InGaN contact layer. The electron blocking layer adopts a p-type Al<y1>Ga<1 y1>N / In<x1>Ga<1 x1>N superlattice structure. Along with the increase of the number of superlattice periods, the InGaN thickness is reduced step by step, the Mg doping concentration is increased step by step and the hole concentration is increased. By the invention, the hole injection efficiency is effectively improved and the electron hole recombination luminous efficiency is enhanced, so the near-ultraviolet LED luminous efficiency is increased.

The presently claimed invention provides a highly conductive composite used for electric charge transport, and a method for fabricating said composite. The composite comprises a plurality of one-dimensional semiconductor nanocomposites and highly conductive nanostructures, and the highly conductive nanostructures are incorporated into each of the one-dimensional semiconductor nanocomposite. The composite is able to provide fast electric charge transport, and reduce the rate of electron-hole recombination, ultimately increasing the power conversion efficiency for use in solar cell; provide fast electrons transport, storage of electrons and large surface area for adsorption and reaction sites of active molecular species taking part in photocatalytic reaction; enhance the sensitivity of a surface for biological and chemical sensing purposes for use in biological and chemical sensors; and lower the impedance and increase the charge storage capacity of a lithium-ion battery.

The invention discloses a hydroxyl oxidize iron modified titanium dioxide composite photocatalyst as well as a preparation method and application thereof. According to the preparation method, FeOOH isprepared by adopting a hydrothermal method, TiO2 sol is prepared by adopting a sol-gel method, an then the FeOOH and TiO2 are uniformly mixed and then are sprayed onto a glass fiber sheet so as to prepare the photocatalyst. The composite photocatalyst has the advantages that the TiO2 is modified by the FeOOH, so that the light absorption wavelength range of the catalyst is expanded, in addition,the photo-induced electron-hole recombination rate in the catalyst is decreased, and therefore the degradation effect of the photocatalyst on organic pollutants, especially malodorous sulfur-containedcompounds is effectively improved. Meanwhile, the preparation method for the catalyst has the advantages of being simple, feasible, mild in reaction condition and wide in application prospect in theaspects of photocatalytic degradation of the organic pollutants and indoor and outdoor harmful gas, especially H2S, SO2, mercaptan, sulfur ether and other malodorous sulfur-contained compounds, environmental protection and the like.

Solar cells are provided with carbon nanotubes (CNTs) which are used: to define a micron / sub-micron geometry of the solar cells; and / or as charge transporters for efficiently removing charge carriers from the absorber layer to reduce the rate of electron-hole recombination in the absorber layer. A solar cell may comprise: a substrate; a multiplicity of areas of metal catalyst on the surface of the substrate; a multiplicity of carbon nanotube bundles formed on the multiplicity of areas of metal catalyst, each bundle including carbon nanotubes aligned roughly perpendicular to the surface of the substrate; and a photoactive solar cell layer formed over the carbon nanotube bundles and exposed surfaces of the substrate, wherein the photoactive solar cell layer is continuous over the carbon nanotube bundles and the exposed surfaces of the substrate. The photoactive solar cell layer may be comprised of amorphous silicon p / i / n thin films; although, concepts of the present invention are also applicable to solar cells with absorber layers of microcrystalline silicon, SiGe, carbon doped microcrystalline silicon, CIS, CIGS, CISSe and various p-type II-VI binary compounds and ternary and quaternary compounds.

The invention discloses a making method of a graphene modified titanium oxide metal anticorrosion coating. The method comprises the following steps: preparing a graphene precursor solution, preparing a titanium oxide sol, preparing graphene modified titanium oxide powder, preparing a silane sol, making a composite coating, and making the metal anticorrosion coating. The thickness of the anticorrosion coating is 200-500nm. TiO2 particles in the graphene modified titanium oxide powder have uniform scales, and are uniformly distributed on a reduced graphene oxide layer, the crystal form structure of TiO2 is an anatase phase and brookite mixed crystal form, and the anatase phase and brookite mixed crystal form forms a compound energy zone structure, so the luminous energy utilization rate of titanium oxide is improved, the transfer path of electrons in the titanium oxide photocathode protection process is prolonged, the electron-hole recombination is reduced, and the photoinduced cathode protection effect of the coating is improved.

This invention discloses a method for preparing highly active titanium dioxide nanosol. The method comprises: (1) weighing titanium oxysulfate or titanium sulfate, adding water to dissolve, dropping base solution to adjust the pH value to above 8, and stirring adequately; (2) filtering, washing the precipitate until there is no sulfate ions, and repeatedly washing with distilled water to neutrality; (3) adding water to the precipitate, mixing uniformly, beating, transferring the slurry to a constant-temperature reaction kettle, adding water, mixing uniformly, dropping acid solution to adjust the pH value to 0.5-2.0, and stirring adequately at normal temperature; (4) stirring the slurry at 40-95 deg.C for 3-60 h; (5) performing high-pressure hydrothermal treatment. The obtained titanium dioxide nanosol is light blue, and does not have any odor or organic matter. Besides, the titanium dioxide nanosol has such advantages as high stability, high crystallinity, high activity, high light transmittance rate, low electron-cavity recombination, high antibacterial and moldproof ability, and no corrosion to matrix. The method has such advantages as simple process and easy operation.

The invention discloses a mesoporous perovskite photovoltaic material and a preparation method thereof. The preparation method of the mesoporous perovskite photovoltaic material specifically comprises the following steps: (1) preparing metal halide nanometer microspheres; and (2) preparing a mesoporous perovskite photovoltaic material. The particle size of the metal halide nanometer microspheres can be adjusted through parameters such as reaction temperature. Therefore, by implementing the technical scheme in the embodiment of the invention, the aperture of the mesoporous perovskite material can be adjusted accurately. For a solar cell prepared by using the mesoporous perovskite material as the absorption layer of the perovskite solar cell, mesopores increase the contact area between the absorption layer and the hole transport layer of the solar cell, and therefore, the number of holes transported by the hole transport layer is increased when the solar cell is working, the electron-hole separation rate is increased, the electron-hole recombination rate is effectively reduced, and the photoelectric conversion efficiency is increased.

The present invention relates to a light emitting diode (LED) including an n-type nitride semiconductor layer, a p-type nitride semiconductor layer, and an active region interposed between the n-type nitride semiconductor layer and the p-type nitride semiconductor layer. The active region may include an InGaN quantum well layer. The LED may further include a super lattice layer interposed between the n-type nitride semiconductor layer and the active region. The super lattice layer may be a structure wherein InN layers and InxGa1-xN (0≦x<1) layers are alternately stacked. The active layer may be formed on the InGaN / InxGa1-xN super lattice layer, so that strain can be relieved in the active region and so that crystallinity of the quantum well can be improved to increase an electron-hole recombination rate.

The invention relates discloses a high-visible-light-activity sulfur-modified carbon nitride photocatalyst as well as a synthetic method and application of photocatalyst, relating to the technical fields of material preparation and photocatalysis and solving the problem of low activity of an existing graphite-phase carbon nitride catalyst caused by the low visible light absorption coefficient and the large electron hole recombination rate. The synthetic method comprises the following steps: (1) grinding melamine and sublimed sulfur, and uniformly mixing the melamine with the sublimed sulfur so as to obtain mixed powder; (2) filling a combustion boat with the mixed powder obtained in the step (1), putting the combustion boat into a tube furnace, heating the tube furnace from the room temperature to 550-650 DEG C according to a heating rate of 5 DEG C / minute-15 DEG C / minute in the presence of argon, keeping the temperature for 1-4 hours, and cooling the tube furnace to room temperature so as to obtain the sulfur-modified carbon nitride photocatalyst. The sulfur-modified carbon nitride photocatalyst disclosed by the invention can be applied to the fields of producing hydrogen by decomposing water by virtue of visible light and degrading pollutants.

The invention relates to a photovoltaic cell, and provides an efficient perovskite solar cell and a preparation method thereof. Structure of the perovskite solar cell is traditional mesoporous structure which comprises a conductive substrate, a semiconductor oxide transmission layer, a mesoporous layer, an organic and inorganic hybrid perovskite layer, a hole transport layer and a metal counter electrode. An insulation buffer layer is introduced into the traditional mesoporous cell structure, and then construction of the efficient perovskite solar cell is achieved. After the buffer thin layer is added into the cell, inhibition of electron-hole recombination at an interface position is facilitated, but a photocurrent is often reduced due to an introduction of an insulation material. However, through interface regulations and control, a current does not decline but is enhanced after the insulation buffer layer is added, cell performance is improved, and a new preparation approach is provided for the efficient perovskite solar cell. The method is simple in process and low in cost, is in favor of improving optical performance and stability of a perovskite photovoltaic device, and has a good application prospect.

The invention provides a method for preparing a p-type AlGaN / AlInGaN electron blocking layer near ultraviolet LED with doping density and Al component in stepwise change. In an LED epitaxial structure, an electron blocking layer adopts a p-type Aly1Ga1-y1N / AlyInx1Ga1-x1N superlattice structure, and the Al component is reduced from 0.2 to 0.05 stepwisely with the increase of superlattice cycle number; Mg doping density increases stepwisely with the increase of superlattice cycle number, and corresponding hole concentration increases from 0.5*10<17> cm<3> to 2* 10<17> cm<3>; the thickness range of the AlGaN barrier layer is 2-5 nm; and the thickness of the GaN well layer is 2 nm-5 nm. Through the design of the novel ultraviolet LED electronic blocking layer structure, hole injection efficiency can be improved effectively, and electron-hole recombination luminescence efficiency is improved, and thus near ultraviolet LED luminescence efficiency is improved.

The invention discloses an improved front electrode of a solar cell, the structure of which is similar to a beam bridge. The front electrode consists of two electrode parts, one of which is a pier part, penetrates a passive dielectric film, and has a bottom in point contact with an emitter region of the solar cell; and the other part of which is a bridge part, covers on the pier part and the passive dielectric film of the solar cell, and has a bottom which does not directly contact the emitter region of the solar cell. The beam bridge electrode only contacts the emitter region of the solar cell at a local position, and compared with the common solar cells, the beam bridge electrode has a smaller metal-semiconductor contact area, therefore, electron-hole recombination caused by metal-semiconductor interfacial energy state is less, the shortwave spectral response of the cell is better, thus being helpful to improving the photoelectric conversion efficiency of the solar cell.

The invention discloses a synthetic method for preparing nanometer cuprous oxide from nitrogen-doped cuprous oxide. The synthetic method comprises the following steps: a, preparing a copper sulfate solution and a urea solution; b, obtaining a solution A by uniformly mixing the copper sulfate solution obtained in step a with the urea solution obtained in step a according to a molar ratio of N:Cu of 0.002-0.04; c, adding an aqueous solution of ammonia to the solution A, fully stirring, adding a sodium hydroxide solution, adding hydrazine hydrate after that the color of the solution changes intoreseda from blue, and obtaining a solution B when the color of the solution changes into reseda from green; and d, stirring the solution B, carrying out pumping filtration on the solution B, and obtaining a finished product the nanometer cuprous oxide prepared from nitrogen-doped cuprous oxide by carrying out vacuum drying on a filter cake. The nanometer cuprous oxide is prepared with the synthetic method for preparing nanometer cuprous oxide from nitrogen-doped cuprous oxide of the invention, so the electron-hole recombination rate is substantially reduced, and the visible photocatalytic activity of the nanometer cuprous oxide is effectively improved.

The invention belongs to the technical field of synthesis of photocatalytic materials and discloses a method for synthesizing rare earth doped potassium titanate powder with photocatalytic activity. The rare earth ion doped potassium titanate photocatalytic powder is prepared through a coprecipitation-fused salt method. Because a visible-ultraviolet upconversion effect of rare earth ions is utilized, the powder has the obvious advantages of high visible light utilization rate, electron-hole recombination probability, high visible light catalytic activity and the like. The experiment proves that the visible light is simulated through a high-pressure halogen lamp, when the concentration of the catalyst is 1g / L, after a 10mg / L of methylene blue solution is catalyzed for 30 minutes, the degradation rate can reach over 92 percent, and the catalyst is superior to a commercially available photocatalyst TiO2 (P25). In addition, compared with a traditional solid phase method, the method has the advantages that the powder is narrow in particle size distribution, controllable in size and uniform in doping.

Fast, bright inorganic scintillators at room temperature are based on radiative electron-hole recombination in direct-gap semiconductors, e.g. CdS and ZnO. The direct-gap semiconductor is codoped with two different impurity atoms to convert the semiconductor to a fast, high luminosity scintillator. The codopant scheme is based on dopant band to dopant trap recombination. One dopant provides a significant concentration of carriers of one type (electrons or holes) and the other dopant traps carriers of the other type. Examples include CdS:In,Te; CdS:In,Ag; CdS:In,Na; ZnO:Ga,P; ZnO:Ga,N; ZnO:Ga,S; and GaN:Ge,Mg.

The loss of photogenerated electrons to surface electron-hole recombination sites is minimized by utilizing a first p-type surface region to form a depletion region that functions as a first barrier that repels photogenerated electrons from the surface recombination sites, and a second p-type surface region that provides a substantial change in the dopant concentration.

The invention provides an electroluminescent device, a display device and a preparation method of the electroluminescent device. The electroluminescent device sequentially comprises a substrate, an anode layer, a luminescent layer and a cathode layer, wherein the anode layer and the cathode layer are respectively connected with the anode and the cathode of a power supply. The electroluminescent device also comprises an inert layer for adjusting electron mobility, and the insert layer is arranged inside the luminescent layer. According to the embodiment of the invention, the insert layer is arranged inside the luminescent layer, so that the influence of voltage on electron-hole recombination in the luminescent layer is reduced, the recombination quantity of carriers such as electrons and holes in the luminescent layer is increased and the recombination ratio of electrons and holes is improved; and consequently the luminescent efficiency of the luminescent layer is enhanced, the prolonging of the service life of the electroluminescent device is benefited and the colors from the electroluminescent device are more stable.

Fast, bright inorganic scintillators at room temperature are based on radiative electron-hole recombination in direct-gap semiconductors, e.g. CdS and ZnO. The direct-gap semiconductor is codoped with two different impurity atoms to convert the semiconductor to a fast, high luminosity scintillator. The codopant scheme is based on dopant band to dopant trap recombination. One dopant provides a significant concentration of carriers of one type (electrons or holes) and the other dopant traps carriers of the other type. Examples include CdS:In,Te; CdS:In,Ag; CdS:In,Na; ZnO:Ga,P; ZnO:Ga,N; ZnO:Ga,S; and GaN:Ge,Mg.

The invention discloses a two-dimensional anatase TiO2 / g-C3N4 composite material. The material is a two-dimensional lamellar structure, and is obtained by compounding g-C3N4 and a TiO2 precursor through a surfactant. The composite material has a thickness of 2 to 20nm, a lateral dimension of 100nm to 2[mu]m and a specific surface area of 88 to 110m<2>*g<-1>. According to the composite material, an ethylene glycol modified Ti-O hydrate-surfactant-g-C3N4 sandwich structure is assembled under hydrophobic and hydrophilic actions, oxygen vacancies in TiO2(B) are supplied by air calcination, and the two-dimensional anatase TiO2 / g-C3N4 composite material is finally obtained to realize close and homogeneous compounding of two ultrathin nanosheets, so that a large-area heterogenous interface is formed, the electron transport rate is increased and light-generated electron home recombination is suppressed; the composite material has very high photocatalytic hydrogen production performance and photocatalytic organic matter degradation activity.

The ZnO-base blue diode comprises: from bottom to top, a circular substrate, a buffer layer prepared on substrate to improve material epitaxial grow quality, a n-ZnO layer with edge etched as ring stage for ring Au / Ti electrode, an i-ZnO active layer for hole-electron recombination, a p-ZnO layer to provide being injected holes; an Au / Ni layer benefit to diffusion of injected current, an Au / Ni electrode contacted with wire, and a ring Au / Ti electrode on the said stage.

The present invention discloses a CdS / BiVO4 compound semiconductor photocatalyst and preparation and application thereof, and belongs to the technical field of environmental material preparation. First, BiVO4 powder is prepared by a solvothermal method, and then a CdS / BiVO4 compound semiconductor is synthesized hydrothermally. The monoclinic BiVO4 is prepared by the method, and the BiVO4 as a carrier is loaded with CdS nanoparticles, the photocatalyst specific surface area is increased, the electron-hole recombination rate is reduced, the BiVO4 photocatalytic activity is improved, and the CdS / BiVO4 compound semiconductor photocatalyst can effectively degrade organic dyes in sewage.

The invention belongs to the technical field of photoelectrons, and relates to a green-yellow light LED with a doped wide potential barrier structure. The green-yellow light LED comprises a buffer layer, a bragg reflecting layer, a first limiting layer, a first non-doped superlattice active layer, a doped wide potential barrier structural layer, a second non-doped superlattice active layer, a second limiting layer and a GaP window layer, wherein the buffer layer grows on one face of a GaAs substrate. A first electrode is arranged on the GaP window layer. A second electrode is arranged on the other face of the GaAs substrate. According to the green-yellow light LED, the hole injection of the active area can be improved, the recombination efficiency of an electron hole is improved, accordingly, the product lighting effect can be greatly improved, the chip pass percent is increased by 2 percent to 4 percent, and therefore, a large number of high-efficiency and high-yield green-yellow light waveband LEDs with the light emitting wavelength ranging from 560 nm to 580 nm can be produced.

The invention discloses a preparation method of a nanorod-like Ag2Mo2O7@AgBr composite photocatalyst. According to the preparation method, nanorod-like Ag2Mo2O7 is prepared by a low-temperature liquid phase constant temperature heating method, and AgBr nano particles are generated on the surface of the Ag2Mo2O7 through an ion exchange method. A monoclinic phase Ag2Mo2O7 is prepared on the basis of the method, and the AgBr nano particles are generated through ion exchange by taking the monoclinic phase Ag2Mo2O7 as a precursor, so that the utilization of visible light by the photocatalyst is increased, the electron-hole recombination rate is decreased, the photocatalysis activity of Ag2Mo2O7 is improved, and rhodamine B dyes can be effectively degraded.

The invention discloses a preparation method of a TiO2-cladded PbS TiO2 / PbS double-layer composite nano tube array. TiO2 acts as a single semiconductor material, defects of high composite rate of photo-generated electrons and electron-hole pairs, low quantum efficiency and the like restrict the catalytic performance to a certain extent, so that TiO2 is relatively low in sewage treatment efficiency. According to the invention, a porous anode oxidized aluminum membrane (AAO) acts as a mold plate, analytic pure Pb(CH3COO)2, Na2S2O3 and TiF4 act as raw materials, and a layer-upon-layer liquid phase assembling technique is adopted, and finally the double-layer composite nano tube array of TiO2 coated PbS can be obtained. The obtained composite nano tube has a double-layer structure, so that the contact area of TiO2 and PbS is increased greatly, and the electron-hole composite probability is reduced, thus facilitating improvement of the photocatalytic performance. A PbS semiconductor is used for modifying TiO2, so that the photoresponse range is widened, and the photocatalytic efficiency is improved. Nano tubes exist in a regular array mode, are easy to recycle from treated sewage so as to prevent secondary pollution. The preparation method has great application significance on the sewage treatment.