ZnO defects involved in energy transfer for ZnO:Tb nanoparticles

ZnO:Tb nanoparticles are prepared by a solvothermal method with the diameter of approximately 18–100 nm. At appropriate doping concentration, the lattice expansion occurs. With the increase in the doping ratio of Tb/Zn from 0 to 0.03, ZnO lattice first contracts slightly, then expands, and finally, contracts again. Tb3+ element is found to enter the ZnO lattice and replace Zn2+. Some crystal defects are generated in the host lattice for doped samples such as Zni and VO. By carefully examining the excitation and emission spectra, both VO and Zni are found to be involved in the energy transfer process. This is different from ZnO:Eu for which negative charge Oi defects are identified to play an important medium of energy transfer from ZnO host to Eu3+. It also supports another charge compensation mechanism. The energy transfer mechanism helps to theoretically explain and promote strong green luminescence of Tb3+ and improves the luminescence intensity of the RE-doped ZnO nanomaterial. It is very valuable for potential applications in bioimaging, photoluminescence, optoelectronics, and photocatalysis. © 2021 Elsevier Ltd