TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The electrolyte is a liquid electrolyte, gel electrolyte, or solid electrolyte. Preferred Cell: The dye-sensitized solar cell comprises a semiconductor electrode, counter electrode, and electrolyte charged between the two electrodes, where the semiconductor electrode has a metal oxide nanoball layer comprising mesoporous nanoballs which are agglomerated metal oxide nanoparticles and have an average diameter of 50-3000 nm and specific surface area of 70-300 m2/g.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The metal oxide dispersion is prepared by dispersing the metal oxide nanoparticles in the organic solvent uniformly using a micro bead mill. Preferred Components: The content of the metal oxide nanoparticles of the metal oxide dispersion is 0.01-3 wt.%. The metal oxide nanoparticles have an average diameter of 1-50 nm, an aspect ratio of 1-100, and a specific surface area of 10-300 m2/g, and are selected from mesoporous nanoparticles, hollow nanoparticles, nanorods, nanotubes, and/or nanofibers. The metal oxide nanoparticles are nanoparticles of a metal oxide selected from titanium oxide, zinc oxide, tin oxide, niobium oxide, tungsten oxide, strontium oxide, and/or zirconium oxide (preferably anatase titanium oxide nanoparticles), and the metal oxide nanoball layer is further coated with a rutile titanium oxide nanoparticle layer. The conductive substrate is a conductive glass substrate or a metal substrate or transparent conductive plastic substrate, and the heat-treatment is conducted at a temperature of 400-700 degrees C (preferably 100-250 degrees C). The metal oxide nanoball layer has a porosity of 70-90%.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic solvent is a mixed solvent composed of ethanol mixed with a solvent having a dielectric constant less than that of ethanol and having a boiling point of 80-150 degrees C, in a weight ratio of 1:3 to 3:1, where the mixed solvent is a mixture of ethanol and butanol in a weight ratio of 1:3 to 3:1. EXAMPLE - A substrate including the titanium oxide layers (12.4 mu m) comprising P-25 (RTM: titanium oxide nanopowder) (having a diameter of 20 nm and a specific surface area of 54 m2/g was uniformly dispersed in a mixed solvent of ethanol and butanol (weight ratio of 1:1) using a micro bead mill to prepare a dispersion) (3 wt.%) was immersed in an ethanol solution in which a N719 (RTM: ruthenium dye) was dissolved in a concentration of 3x 10-4 M for 12 hours to allow the substrate to adsorb the ruthenium dye, and then, the dye-adsorbed substrate was washed with ethanol and dried several times to prepare a dye-adsorbed semiconductor electrode. The semiconductor electrode and the counter electrode were attached to each other by slightly pressing them at 120 degrees C in a state in which a spacer having a thickness of about 20 mu m was interposed between the two electrodes. A liquid iodine electrolyte (comprising hexyldimethylimidazolium iodine (0.6 M), guanidine thiocyanate (0.1 M), iodine (0.03 M) and quaternary butylpyridine (0.3 M) in a mixed solution of acetonitrile and valeronitrile (volume ratio of 4:1.)) was charged in the space between the two electrodes and then sealed, to form a dye-sensitized solar cell (test). A comparative dye-sensitized solar cell was prepared in same as test cell, comprising substrate including the titanium oxide layers (12.4 mu m) comprising P-25 (12 wt.%) (having a diameter of 20 nm and a specific surface area of 54 m2/g) was uniformly dispersed in water using a ball mill and ultrasonic waves, and then, polyethylene glycol (PEG) (20 wt.%) and polyethylene oxide (PEO) (15 wt.%) were added as a binder. The photoelectric conversion shown by test/comparative was found to be 8.12/6.81%.