Concentration and temperature dependence of visible up-conversion luminescence in sol-gel SnO2 doped with erbium

A sol-gel method was used to prepare erbium (Er3+)-doped tin dioxide (SnO2). Photoluminescence (PL) properties of Er3+-doped SnO2 were investigated using a 798-nm excitation wavelength. We show efficient green and red up-conversion emissions by varying the concentration of erbium. The study of the 4S3/2 → 4I15/2 (545 nm) and 4F9/2 → 4I15/2 (647 nm) transition intensities of Er3+ versus the laser pump power has evidenced a two-step up-conversion process. It was found that the increase of Er3+ concentration leads to a considerable enhancement of the red up-conversion emission compared to the green one. This behaviour has been explained in terms of an energy transfer between excited ions. By increasing the temperature in the range 80–300 K, the up-conversion PL intensity of both green and red presents a weak quenching. This weak thermal quenching is related to the excitation mechanism of Er in SnO2 host where the multiphonon process is not probable.