Basic study for the construction of solar cell using CdS photocatalysts and Na₂S₄ electrolyte

Photoexcited electrons pathway from thin film consisting of semiconductor particles to electrode was tried to develop by using conducting polymers. PEDOT/PSS and polyaniline was selected as transparent conducting polymer material. In the case of the cell consisted by using polyaniline, it was confirmed that conductive emeraldine salt stated polyaniline converted to non-conductive emeraldine base state because of contact with strong basic Na₂S₄ electrolyte solution. On the other hand, as regards the cell with PEDOT/PSS, it was expected that positive and negative electrode short-circuited and/or Schottky junction was formed between CdS and PEDOT/PSS. The formation of Schottky junction between CdS and PEDOT/PSS was reduced the kinetic energy of the photoexcited electrons to 5.1eV which was the Fermi level of PEDOT. These electrons could not reduce Na₂S₄ electrolyte solution since oxidation-reduction potential was 4.1eV. As a result, it considered that photoexcited electrons transfer was restricted, which read the decreasement of mobility of photoexcited electron, while the cell "without" PEDOT/PSS could operate as a solar cell.