Enhanced up-conversion luminescence intensity in single-crystal SrTiO3: Er3+ nanocubes by codoping with Yb3+ ions

Abstract

A series of Er3+ doped and Er3+/Yb3+ codoped SrTiO3 nanocubes with varying dopant concentrations have been successfully synthesized by a facile hydrothermal method. The doping effects on phase purity, morphology and microstructure of samples were identified by power X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that SrTiO3 nanocubes have a typical perovskite structure with the edge length ranging 20–50 nm. The Er3+ and Yb3+ ions were successfully doped into the crystal lattice of SrTiO3, but did not alter crystal structure of SrTiO3. The photon up-conversion (UC) photoluminescence (PL) measurements indicated that the intense green light emission of Er3+ ions around 525 nm, 550 nm and red light emission centered at 670 nm in UC processes populated by 980 nm laser excitation have been achieved in SrTiO3 nanocubes. Moreover, the PL intensity of Er3+-doped SrTiO3 nanocubes was greatly enhanced while introducing the Yb3+ to the crystal structure, especially the red emission. The mechanisms for these emissions probably due to the excited state absorption (ESA) and energy transfer (ET) process. Er3+/Yb3+-codoped single-crystal perovskite SrTiO3 nanocubes could be interesting objects for applications in mechanical−electrical luminescence such as electric field modulation luminescence and mechanoluminescence.