Abstract: The present disclosure relates to an organic electroluminescent compound, a plurality of host materials, and an organic electroluminescent device comprising the same. By comprising the compound according to the present disclosure or by comprising a specific combination of compounds according to the present disclosure as a plurality of host materials, it is possible to produce an organic electroluminescent device having improved driving voltage, luminous efficiency, and/or lifetime properties compared to the conventional organic electroluminescent devices.

Abstract: The present disclosure relates to a plurality of host materials comprising a first host material comprising a compound represented by formula 1, and a second host material comprising a compound represented by formula 2, and an organic electroluminescent device comprising the same. By comprising a specific combination of compounds as host materials, it is possible to provide an organic electroluminescent device having lower driving voltage, higher luminous efficiency, higher power efficiency, and/or superior lifespan characteristics compared to conventional organic electroluminescent devices.

Abstract: Provided are a method of manufacturing a metal oxide and a substrate for a solar cell. The method of manufacturing the metal oxide according to the inventive concept includes mixing a metal precursor material, a basic material, amphiphilic molecules and distilled water to prepare a metal precursor solution, performing a first heat treatment with the metal precursor solution to form a metal oxide, and performing a second heat treatment with the metal oxide to form a pair of metal oxide disks having a single crystalline structure. A pair of zinc oxide disks includes a first disk, and a second disk separated from the first disk in a perpendicular direction to the first disk.

Abstract: A method of fabricating a metal oxide sheet having a polycrystalline structure includes mixing a metal precursor material, a base material, and distilled water with each other to fabricate a preparation solution; adding an anionic surfactant into the preparation solution to forming a precursor solution; forming metal oxide nanoparticles in the precursor solution, wherein each of the metal oxide nanoparticles comprises a metal cation and an oxygen anion; and fabricating a metal oxide sheet by coupling the metal oxide nanoparticles to each other, wherein, in an aspect of a plane, the metal oxide sheet has a hexagonal shape and a polycrystalline structure.

Abstract: Provided is a method of fabricating metal oxide. The method includes mixing a metal precursor material, a base material, and distilled water with each other to fabricate a preparation solution, adding an anionic surfactant into the preparation solution to forming a precursor solution, forming metal oxide nanoparticles in the precursor solution, and fabricating a metal oxide sheet by coupling the metal oxide nanoparticles to each other. The polycrystalline metal oxide may have a sheet or nanowire shape.

Abstract: A method of manufacturing a graphene-containing electrolyte includes, in the order recited: (a) deoxidizing graphene oxide to form graphene; (b) dissolving the graphene in a carbonate solvent to provide a graphene-containing solution; and (c) adding an oxidation-reduction agent composed of 1-butyl-2,3-dimethylimidazolium iodide (BDI) and optionally iodine (I2) into the graphene-containing solution to provide the graphene-containing electrolyte. Deoxidizing the graphene oxide may be accomplished by dissolving the graphene oxide in an aqueous solvent that is a mixture of water and an alkyl imidazole-based iodine to form a solution; and centrifuging the solution to obtain the graphene. A dye-sensitized solar cell may include the graphene-containing electrolyte to fill a space defined between first and second electrodes.

Abstract: Provided are a method of manufacturing a metal oxide and a substrate for a solar cell. The method of manufacturing the metal oxide according to the inventive concept includes mixing a metal precursor material, a basic material, amphiphilic molecules and distilled water to prepare a metal precursor solution, performing a first heat treatment with the metal precursor solution to form a metal oxide, and performing a second heat treatment with the metal oxide to form a pair of metal oxide disks having a single crystalline structure. A pair of zinc oxide disks includes a first disk, and a second disk separated from the first disk in a perpendicular direction to the first disk.

Abstract: A method of fabricating a transparent electrode includes preparing conductive nanoparticles, preparing a metal oxide sol, mixing and reacting the conductive nanoparticles with the metal oxide sol to form a metal oxide solution including a metal oxide combined with the conductive nanoparticles, coating the metal oxide solution on a substrate, and performing an annealing process on the coated metal oxide solution.

Abstract: Provided are a method of forming metal oxide nanotube and a dye-sensitized solar cell formed thereby. The method may include providing a metal electrode and a counter electrode in an electrolyte containing a negatively polarized surfactant, and applying voltages to the metal electrode and the counter electrode to form a metal oxide nanotube on the metal electrode. The metal oxide nanotube may have a (001)-plane.

Abstract: Provided is a method of forming a method of forming a titanium dioxide (TiO2) array using a zinc oxide (ZnO) template. In the method, polymer nanopatterns are formed on the substrate, and monomolecular monolayers are formed between the polymer nanopatterns on the substrate. A seed layer pattern is formed between the monomolecular monolayers on the substrate, and a zinc oxide template is formed by growing zinc oxide on the seed layer.

Abstract: Provided are solar cells and methods of forming the same. The solar cell includes an anti-reflection layer on a substrate, a first electrode on the anti-reflection layer, a photo-electro conversion layer on the first electrode, and a second electrode on the photo-electro conversion layer.

Abstract: The present invention relates to an apparatus and method for measuring the convective heat transfer coefficients of nanofluids, which can realize a small-sized structure and can accurately control the movement velocity of a hot wire sensor within a fluid. The apparatus for measuring the convective heat transfer coefficients of nanofluids according to the present invention includes a sensor unit, a transfer unit and a liquid container. The transfer unit is formed on the sensor unit and is configured to allow the sensor unit to longitudinally reciprocate in a direction parallel to a ground surface with the sensor unit spaced apart from the ground surface. The liquid container is arranged below and spaced apart from the sensor unit, and is configured to allow a nanofluid or a base fluid, a convective heat transfer coefficient of which needs to be measured, to be put therein.

Abstract: Provided are solar cells and methods of manufacturing the same. The solar cell includes a first electrode, a second electrode facing and separated from the first electrode, and a quantum dot-graphine hybrid composite disposed between the first and second electrodes. Quantum dots are combined with graphine in a ?-bond within the quantum dot-graphine hybrid composite.

Abstract: Provided are a solar cell and a method of fabricating the same. The solar cell may include a first electrode including a first substrate attached with a first transparent conductive film and a metal oxide nanotube provided on the first substrate and adsorbed with a dye, a second electrode facing the first electrode, and an electrolyte filling between the first and second electrodes. In example embodiments, metal nanoparticles may be provided on an inner surface of the metal oxide nanotube.

Abstract: Embodiments of the inventive concept provide dye-sensitized solar cells and methods of manufacturing an electrolyte. The dye-sensitized solar cell may include a first electrode, a second electrode facing and spaced apart from the first electrode, and an electrolyte filling a space between the first and second electrode. The electrolyte may include a solvent including graphene of about 60 mg to about 100 mg dissolved in carbonate of about 10 ml, and an oxidation-reduction agent including alkyl imidazole-based iodine and iodine of about 0.2M to about 0.6M and iodine of about 0.01M to about 0.03M.

Abstract: Provided are a mixed nano-lubricating oil and a method for preparing the same. The method for preparing a mixed nano-lubricating oil includes the steps of: (a) preparing a mixed solution by adding and mixing a nanopowder and a dispersant to a solvent and pulverizing the nanopowder to a primary particle level; (b) modifying the surface of the nanopowder; (c) substituting the solvent of the mixed solution to a lubricating oil; and (d) mixing at least two nano-lubricating oils prepared using physically and chemically different nanopowders. According to the present invention, it is possible to improve the wear resistance and the load resistance at the same time by mixing at least two kinds of lubricating oils having excellent wear resistance or load resistance.

Abstract: Provided are methods of forming a nano structure and method of forming a solar cell using the same. The method of forming the nano structure includes: preparing a template; ionizing a surface of the template; forming an oxide layer enclosing the template on the surface of the template; and removing the template.

Abstract: Provided is a method of forming a method of forming a titanium dioxide (TiO2) array using a zinc oxide (ZnO) template. In the method, polymer nanopatterns are formed on the substrate, and monomolecular monolayers are formed between the polymer nanopatterns on the substrate. A seed layer pattern is formed between the monomolecular monolayers on the substrate, and a zinc oxide template is formed by growing zinc oxide on the seed layer.

Abstract: Provided are solar cells and methods of forming the same. The solar cell includes an anti-reflection layer on a substrate, a first electrode on the anti-reflection layer, a photo-electro conversion layer on the first electrode, and a second electrode on the photo-electro conversion layer.

Abstract: Disclosed is a heat transfer evaluation apparatus of a nano-fluid including: a long pipe formed as a circular pipe; a rubber tube connected to one end of the long pipe to surround the outer surface of the long pipe; a short pipe communicated through the rubber tube; and a hot wire sensor formed of a metal hot wire at one end of the short pipe.