Saturday, November 28, 2009

Taiwan Scientists Use Nanoparticles to Solve Lifetime Problem for Dye-Sensitized Solar Cells

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Atomic Energy Council - Institute of Nuclear Energy Research (Taoyuan, TW) scientists have fabricated a longlife Dye-Sensitized Solar Cell using nanoparticles of InN(indium nitride)/TiO2 (titanium oxide) to create a novel photosensitized electrode. It is comprised  of an indium tin oxide (ITO) substrate, a TiO2 film and an InN photosensitive layer.   The photosensitized electrode can be fabricated at a low cost and with long lifetime in a solar cell device with enhanced absorbing ability.  The solar cell is an InN/TiO2 photosensitized electrode, where a lifetime issue of the dye for a Dye-Sensitized Solar Cell (DSSC) is solved; an optical absorption efficiency is enhanced; a production procedure is simplified; and a production cost is reduced to 1/5 to 1/10 of current manufacturing processes, say inventors Ming-Chang Lin, Yen-Chang Tzeng, Shan-Ming Lan, Yuan-Pern Lee, Wei-Guang Diau, Tsong-Yang Wei, Jyh-Perng Chiu, Li-Fu Lin, Der-Jhy Shieh and Ming-Chao Kuo in U.S. Patent 7,622,397.

The substrate can also be a fluorine tin oxide (FTO) glass or other transparent conductive substrate.  The TiO2 film has a nanoparticle structure, where nanoparticles are evenly distributed in the  film and where each nanoparticle has a diameter between 7 nm (nanometer) and 50 nm. The TiO2 film has a thickness between 100 nm and 100,000 nm and is made of a metal oxide with a high band-gap.  The InN photosensitive layer is made through a chemical vapor deposition (CVD), a physical vapor deposition (PVD) or other epitaxial film growth method. The InN photosensitive layer is coated on the TiO2 film. The InN photosensitive layer has a thickness between 1 nm and 10000 nm. When a light penetrates through the substrate of the photosensitized electrode into the photosensitive layer, an electron is injected into the TiO2 film from the InN photosensitive layer and then the electron is conducted to an outside circuit from the substrate, where the InN photosensitive layer absorbs an optical wavelength between 390 nm and 800 nm.

FIG 2. shows a simplified schematic for production of Dye-Sensitized Solar Cell developed at Taiwan's Institute of Nuclear Energy Research.

Step (a): A substrate coated with a TiO2 film is placed into a reaction chamber  where the TiO2 film is coated on the substrate through a CVD or a PCD.

Step (b): A hydrazoic acid (HN3) and a compound containing indium  is introduced into the reaction chamber 2, where the ratio of HN3 to the compound containing indium is between 1 and 10. The compound containing indium is a trimethylindium, a triethylindium, a indium-containing metallo-organic precursor or a combination of indium-containing metallo-organic precursors. The process uses the HN3 and the compound containing indium as precursors; and the HN3 can be replaced with a compound containing nitrogen.

Step (c) The substrate is then illuminated with an ultraviolet (UV) light, where the UV light is obtained from a continuous UV lamp, an excimer laser, a semiconductor laser, a gas laser, a solid-state laser, a liquid laser, a chemical laser or a free-electron laser, and where the TiO2 film bears a temperature between 600.degree. C. (Celsius degree) and 900.degree. C.

Step (d): An InN photosensitive layer is obtained on the TiO2 film. Thus, an InN photosensitized electrode is obtained through the above steps, where the total process time is between 1 hr and 8 hr.


1 comment:

  1. Wow, great article, I really appreciate your thought process and having it explained properly, thank you!

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