Erbium upconversion luminescence from sol-gel derived multilayer porous inorganic perovskite film

Erbium-doped barium titanate (BaTiO3:Er) xerogel film with a thickness of about 500 nm was formed on the porous strontium titanate ( SrTiO 3 ) xerogel film on Si substrate after annealing at 800 ∘ C or 900 ∘ C. The elaborated structures show room temperature upconversion luminescence under 980 nm excitation with the photoluminescence (PL) bands at 523, 546, 658, 800 and 830 nm corresponding to 2 H 1 1 / 2 → 4 I 1 5 / 2 , 4 S 3 / 2 → 4 I 1 5 / 2 , 4 F 9 / 2 → 4 I 1 5 / 2 and 4 I 9 / 2 → 4 I 1 5 / 2 transitions of trivalent erbium. Raman and X-ray diffraction (XRD) analysis of BaTiO3:Er\porous SrTiO3\Si structure showed the presence of perovskite phases. Its excellent up-conversion optical performance will greatly broaden its applications in perovskite solar cells and high-end anti-counterfeiting technologies.