Electroluminescence at the n-TiO2/electrolyte interface

We have observed electroluminescence at the n-TiO2/electrolyte interface under strong polarization of TiO2 electrodes above 8 V versus SCE. The quantum yield, obtained from current and intensity measurements at 10 V versus SCE, was in a range between 10−3 and 10−4. The emission spectrum, measured by optical glass filters, was found to be distributed in a range between 450 and 800 nm, the spectrum peak being approximately 630 nm, which is equivalent to a photon energy of 2.0 eV. This luminescence has been attained to the radiative recombination of electrons in some surface states with holes created in the valence band by electron tunneling.