In brief, the cell uses n-type metal-oxide semiconductor (e.g. titanium dioxide (TiO2), tin oxide (SnO2) and zinc oxide (ZnO)) particles covered with an insulating film (an insulating resin or inorganic insulator) for the charge layer.
A number of new energy levels are formed in the bandgap (gap between valence and conduction bands) of the n-type metal-oxide semiconductor by applying ultraviolet light to the charge layer under certain conditions in the manufacturing process. Electrons come into the levels at the time of charging the cell, and they are released at the time of discharging it. As a result, it functions as a rechargeable battery.
First, negative electrodes (indium oxide doped with tin or ITO) and n-type metal oxide semiconductor layer (TiO2) are formed on a substrate by sputtering. Then, fatty acid titanium, silicone oil and solvent are mixed and stirred, and the TiO2 layer is spin-coated with it. It is dried at a temperature of 50°C for 10 minutes and calcinated at a temperature of 300-400°C for 10 to 60 minutes.
As a result, the fatty acid titanium is decomposed, forming a TiO2 particulate layer coated with silicone. When an ultraviolet light with a wavelength of 254nm is applied to it with an intensity of 20mW/cm2 for about 40 minutes, a number of new energy levels, which contribute to charge and discharge of the battery, are formed in the bandgap of TiO2. The p-type metal oxide semiconductor (NiO) and positive electrodes are formed by sputtering.
