Decay kinetics of the defect-based visible luminescence in ZnO

Fabrication of highly efficient ZnO nanoscintillators

“…Exciton luminescence shows characteristic long-wavelength shift of maximum with increasing temperature which is due to well-known low energy shift of the absorption edge [2,3,27]. Almost two orders of magnitude decrease of emission intensity is obtained at room temperature compared to the lowest temperatures which was ascribed to thermal quenching/disintegration of the exciton state [30,8]. There is a clear shoulder within 400-470 nm in emission spectra of ZnO:Ga,La, well visible at temperatures below 140 K. To our best knowledge, emission in this spectral range has not been reported in ZnO-based material and might be related to deeply localized excitons in the ZnO nanoparticle e.g.…”

“…Well-known and complex visible defect-based emission [6] does not have a unique explanation so far and is undoubtedly very much preparation technology-dependent [7]. Due to its slow decay [8] it cannot be exploited for fast scintillators, however. ZnO in the form of powders, thin films, nanowires, nanorods or quantum dots has been intensively studied due to its piezoelectric, pyroelectric, photocatalytic, conductive and optical properties [9][10][11].…”

Study on the Luminescence and Energy Level of Lanthanide Ions in Lu0.8Sc0.2BO3 Host

“…For example, the energy gap between the lanthanide ion ground state and the host conduction band can be deduced by photoluminescence and decay time measurements as a function of temperature. − Specifically, the energy difference between the lowest 5d 1 excited level of Ce 3+ and the conduction band can be deduced from the temperature dependence of Ce 3+ nanosecond decay times, which become shorter due to an autoionization process. For Ce 3+ in the Lu 0.8 Sc 0.2 BO 3 host, we have located the lowest 5d excited level at an energy of 0.35 eV below the conduction band, as sketched in Figure with arrow 2.…”

“…The spectroscopic parameters are derived from the charge transfer transitions in the Lu 0.8 Sc 0.2 BO 3 doped with Eu 3+ and Yb 3+ , and the d–f transitions in Lu 0.8 Sc 0.2 BO 3 doped with Ce 3+ , Pr 3+ , Nd 3+ , and Tb 3+ . Furthermore, the photoluminescence and decay time measurements as a function of temperature − have been utilized to construct the relative energy position between the trivalent lanthanide (Ce 3+ , Pr 3+ ) lowest 5d state and the conduction band.…”