Effect of Rare-Earth Doping on Structural and Luminescent Properties of Screen-Printed ZnO Films

Abstract

The effect of Sm3+ and/or Ho3+ doping on structural and luminescent properties of screen-printed ZnO films sintered at 1000°C was investigated by photoluminescence (PL), PL excitation and Raman scattering methods. For all the films, ultraviolet excitonic and visible defect-related PL bands of ZnO were detected. The doping with Ho3+ ions produced an enhancement of PL in ZnO films, the excitonic PL intensity being increased prominently, while the co-doping with Sm3+ and Ho3+ ions resulted in PL decrease in ZnO films. Only for (Sm,Ho)- co-doped ZnO films, the rare-earth PL bands were detected. The reduction of Sm3+ to Sm2+ was observed demonstrating 5D0→7FJ radiative transitions. The mechanism of PL and PL excitation is discussed in terms of the formation of rare-earth complexes as well as energy transfer towards them from ZnO host.

Encapsulation of ZnO and Ho:ZnO Nanoparticles in the Core of Wrinkled Mesoporous Silica

“…This shift can be attributed to the presence of holmium, which introduces energy levels near the conduction band edge, effectively narrowing the effective band gap of the doped ZnO nanoparticles . This phenomenon suggests a higher concentration of defects and substoichiometry within the doped material. , Furthermore, the increased intensity of the visible emission peak relative to the UV emission peak suggests a higher concentration of defects in the nanoparticles, likely arising from oxygen vacancies and zinc interstitials. − These defects give rise to trapped states in the band gap, resulting in visible emission peaks in ZnO nanoparticles. Notably, the PL emission intensity of the Ho:ZnO nanoparticles in the visible range exhibits a unique pattern.…”

“…68 This phenomenon suggests a higher concentration of defects and substoichiometry within the doped material. 68,69 Furthermore, the increased intensity of the visible emission peak relative to the UV emission peak suggests a higher concentration of defects in the nanoparticles, likely arising from oxygen vacancies and zinc interstitials. 69−71 These defects give rise to trapped states in the band gap, resulting in visible emission peaks in ZnO nanoparticles.…”