Application of Inorganic Redox-Conducting Solids As Charge Relays in Dye- Sensitized Solar Cell

摘要

Polynuclear redox conducting mixed-valent inorganic materials, such as sol-gel processed nanostructured nickel(Ⅱ) hexacyanoferrate(Ⅱ,Ⅲ), have been utilized as redox mediators (charge relays) in dye-sensitized solar cell (DSSC). The systems' granules are likely to penetrate pores of the dye-modified TiO_2. An important issue is that the formal potential of nickel(Ⅱ) hexacyanoferrate(Ⅱ,Ⅲ) is more positive (>300 mV) relative to the commonly used iodide/triiodide couple. With the same dye-modified TiO_2 used, the above property led to the larger potential output of DSSC. The proposed redox-conducting inorganic materials is in a mixed-valent state in which iron(Ⅱ) and iron(Ⅲ) sites are at the 1:1 ratio, and the concentration gradients are maximized. Consequently, the system is characterized by fast dynamics of electron transfers. Since the structures are hydrated, they are also good ionic (K~+) conductors. An important feature is high physicochemical stability of such inorganic polynuclear electroactive materials.