Thin Film InN/Anatase Bilayers as a Substitute Dye/Semiconductor Interface for Solar Cells

Abstract

The electronic properties of an InN/anatse-TiO 2 bilayer, proposed as a replacement for the dye/semi-conductor interface in Dye Sensitized Solar Cell[1, 2], are measured. RF sputtered thin films of TiO 2 and InN are used as the "dye" replacement. . Two types of InN film are prepared: polycrystalline samples deposited at high temperature, with an optical band gap of < 1 eV, and as-deposited (at least partially amorphous) samples with an optical band gap >1 eV. Energy Dispersive X-ray fluorescence, X-ray Diffraction, and Raman spectroscopy are used to characterize the samples. The sample resistance is measured in the dark and under illumination. The samples deposited at high temperature are crystalline and have a sheet resistivity ≈ 4 Ω /□, and display no photoconductivity. The partially amorphous samples have sheet resistivity of ≈ 500Ω/□. Since both types of InN films, including high quality (based on band gap) polycrystalline InN, do not show increased conductivity with light, we conclude that a solar cell based on an InN/TiO 2 bilayer is not feasible.