Electroluminescence in nanoporous TiO2 solid-state heterojunctions

We report visible electroluminescence at room temperature in nanoporous TiO2 films using solid-state heterojunction contacts. Electrons are injected from an n-type polymer layer, while hole injection occurs from a conductive SnO2 substrate. As the polymer material penetrates into the TiO2 nanopore structure a highly non-planar interface with a greatly enlarged area is created. This type of interface establishes very short current paths to the recombination region of the device and allows high carrier fluxes from the electron-injecting contact. The electroluminescence onset occurs at 7 V applied bias, and involves a broad emission band covering most of the visible region with a peak centred at 600 nm.