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

Abstract

Erbium-doped barium titanate (BaTiO3:Er) xerogel film with a thickness of about 500 nm was formed on the porous strontium titanate (SrTiO[Formula: see text] xerogel film on Si substrate after annealing at 800[Formula: see text]C or 900[Formula: see text]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 2H[Formula: see text]4I[Formula: see text], 4S[Formula: see text]I[Formula: see text], 4F[Formula: see text]I[Formula: see text] and 4I[Formula: see text]4I[Formula: see text] 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.

Optical Properties and Upconversion Luminescence of BaTiO3 Xerogel Structures Doped with Erbium and Ytterbium

“…The porous SrTiO 3 sublayer had approximately the same thickness (~600 nm), so the entire thickness of the BaTiO 3 :(Er,Yb)/SrTiO 3 structure was about 1.2 μm ( Figure 1 b). The morphology of samples A and B was similar to that of samples C and D, respectively [ 16 ].…”

“…The upconversion PL spectrum of the sample B taken under CW excitation at a wavelength of 980 nm is shown in Figure 2 . For the sample A without a porous SrTiO 3 sublayer, upconversion PL was not detectable under the same excitation conditions [ 16 ]. The reason for the enhancement of the upconversion luminescence of erbium-doped xerogel could be the multiple scattering of the excited light in the presence of porous strontium titanate layer [ 16 ].…”

“…For the sample A without a porous SrTiO 3 sublayer, upconversion PL was not detectable under the same excitation conditions [ 16 ]. The reason for the enhancement of the upconversion luminescence of erbium-doped xerogel could be the multiple scattering of the excited light in the presence of porous strontium titanate layer [ 16 ]. The observed upconversion PL spectra are characterized with several PL bands at 410, 523, 546, 658, 800 and 830 nm corresponding to 2 H 9/2 → 4 I 15/2 , 2 H 11/2 → 4 I 15/2 , 4 S 3/2 → 4 I 15/2 , 4 F 9/2 → 4 I 15/2 and 4 I 9/2 → 4 I 15/2 transitions of trivalent erbium ions.…”

“…Returning to the posible reasons for the influence of the SrTiO 3 layer on the efficiency of upconversion PL, we assume that the presence of such a porous layer coated with relatively dense barium titanate doped with erbium and ytterbium provides the presence of erbium and ytterbium in the meso- and macropores of the strontium titanate layer and on the interface between the porous strontium titanate layer and the denser barium titanate layer [ 16 ]. Thus, an erbium containing inhomogeneous structure is formed, which consists of components with low and high refractive indices, in particular, air in the volume of the pores and islands of perovskites.…”

“…Europium luminescence and erbium upconversion luminescence was enhanced in sol-gel derived microcavities [ 13 , 14 , 15 ]. We recently reported that the erbium upconversion luminescence from xerogels can be enhanced when xerogels are fabricated on mesoporous and macroporous layers, such as porous strontium titanate xerogel [ 16 ]. The production of multilayer coatings increases the quality factor of the microcavity, but together with an increase in the required annealing temperature, it increases the cost of the product.…”