Electrochromic windows could reudce air-conditioning costs by being darkened to absorb sunlight and reject unwanted solar heat. These windows change their color and light transmissivity due to the action of an electric field and can change back to the original state by a field reversal. To save the cost, the electrical power may be supplied by a solar cell that itnegrated with the electrochromic window in a single device. This paper reports the potential of using titanium oxide, TiO_2 as solar cells and as electrochromic windows. The TiO_2 films were deposited by screen-printing a paste, consisting of TiO_2 particles and an organic binder, onto ITO-covered glass substrates. Then the films were tempered at 400 deg C to turn otu the orgnaic parts. A solar cell of ITO/TiO_2/electrolyte/ITO was fabricated using a mixed ammonium iodide and iodine solution as electrolyte. The cell was illumianted through the TiO_2 film. The cells showed rectifier properties in the dark and produced electrical current when illuminated. The short circuit photocurrent and the open circuit voltage of the cell in a 100-mW/cm~2 tungsten light source were 2.3 mu A 17.0 mV respectively. The electrochromic behavior of the TiO_2 films in a lithium perchlorate solution was examined. When the electrochromic film cell was given a forward bias potential of 5.0 V, the original colorless TiO_2 film immediately changed to brown. The color of the film bleached to the original when the applied potential was reversed.
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