Electrochemical Characterization of Nanoporous Nickel Oxide Thin Films Spray-Deposited onto Indium-Doped Tin Oxide for Solar Conversion Scopes

Figure 25

Hypothesis of mechanism of electrochemically induced charge injection from photoexcited ERY sensitizer to mesoporous RDS/CS NiO_x within the potential range of NiO_x oxidation (2.8–3.7 V versus Li⁺/Li). (a) Electron is injected in the valence band (VB) of oxidized RDS/CS NiO_x from excited ERY colorant; (b) upon neutralization of the hole that has been electrochemically injected in NiO_x the colorant ERY would retain a positive charge with formation of the combination ERY⁺-NiO_x. (c) NiO_x can regenerate the hole by back donation of an electron from the VB of neutral NiO_x to the HOMO of ERY⁺. Further electrochemical oxidation of NiO_x can occur also when the dye sensitizer is in the oxidized state (not shown).

(a)

(b)

(c)