Optically Active TiO2:Er Thin Films Deposited by Magnetron Sputtering.

Anna Kot,Dominik Dorosz,Katarzyna Zakrzewska,Marta Radecka

doi:10.3390/ma14154085

Abstract

Titanium dioxide photoanodes for hydrogen generation suffer from a profound mismatch between the optical absorption of TiO2 and the solar spectrum. To solve the problem of low solar-to-chemical efficiency, optically active materials are proposed. In this work, TiO2 thin films containing erbium were deposited by radio frequency RF magnetron sputtering under ultrahigh vacuum conditions UHV. Morphology, structural, optical and electronic properties were studied. TiO2:Er thin films are homogenous, with uniform distribution of Er ions and high transparency over the visible VIS range of the light spectrum. However, a profound 0.4 eV blue shift of the fundamental absorption edge with respect to undoped TiO2 was observed, which can be attributed either to the size effect due to amorphization of TiO2 host or to the onset of precipitation of Er2Ti2O7 nanocrystals. Near-infrared NIR to VIS up-conversion is demonstrated upon excitation at 980 nm, while strong green photoluminescence at 525 and 550 nm occurs upon photon absorption at 488 nm.

Highlights

Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al
Luminescence from glasses containing lanthanide ions is widely exploited in sensor devices, solid-state lasers, telecommunication fibers, displays, plasma monitors, solar cells, optical thermometers, etc. [1,2,3,8,9]
Down- and up-conversion belong to a group of nonlinear optical processes and can be classified as light management techniques [10]

Summary

Introduction

Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. A. Mickiewicza 30, Faculty of Computer Science, Electronics and Telecommunications, AGH University of Science and. Titanium dioxide photoanodes for hydrogen generation suffer from a profound mismatch between the optical absorption of TiO2 and the solar spectrum. TiO2 :Er thin films are homogenous, with uniform distribution of Er ions and high transparency over the visible VIS range of the light spectrum. Active materials that exhibit either down or up-conversion of light frequency are gaining rapidly new and versified fields of applications in optoelectronics, photonics, bioengineering and photocatalysis [1,2,3,4,5,6,7]. The choice of particular RE ions remains a key factor, but the properties of the host material are important for the efficiency of the process

Methods

Results

Conclusion