Energy conversion modeling of the intrinsic persistent luminescence of solids via energy transfer paths between transition levels

Abstract

An energy conversion model has been established for the intrinsic persistent luminescence in solids related to the native point defect levels, formations, and transitions. In this study, we showed how the recombination of charge carriers between different defect levels along the zero phonon line (ZPL) can lead to energy conversions supporting the intrinsic persistent phosphorescence in solids. This suggests that the key driving force for this optical phenomenon is the pair of electrons hopping between different charged defects with negative-U. Such a negative correlation energy will provide a sustainable energy source for electron-holes to further recombine in a new cycle with a specific quantum yield. This will help us to understand the intrinsic persistent luminescence with respect to native point defect levels as well as the correlations of electronics and energetics.

Doping of RE ions in the 2D ZnO layered system to achieve low-dimensional upconverted persistent luminescence based on asymmetric doping in ZnO systems

“…Indeed, red emission is supported by interdefect-level transitions among the zero-phonon lines (with negative U eff ), leading to enhanced luminescence. 51 Er doped in ZnO has been experimentally reported to generate NIR output luminescence at approximately 1540 nm (0.8 eV photon energy). 110 In the Er 2+ excited levels shown in Fig.…”

“…Our recent work was consistent with the Leverenz model in that energy transfer in persistent luminescence is likely independent of the temperature but is strongly correlated with electron-lattice coupling in the defect states. 51 Currently, no universal analytic theoretical equations for the decay time exist; however, the decay time can be expressed by an effective multicenter emission approximation with consideration of the thermal effects as follows:…”

“…Our recently developed model shows that the long-decay recombination behavior of excited electron-hole pairs occurs through a time-accumulated donoracceptor band, which has been continuously pumped by local lattice distortions with a corresponding negative effective correlation energy. [49][50][51] Our model not only combines a lattice relaxation model resulting from defects such as DX and EL2 centers 52,53 and an energy barrier model involving the photogenerated Coulomb potential from electron-hole pairs, [54][55][56] but also shows a potential zero-phonon line electronic inter-band transition, which can explain the energy conversion mechanism leading to persistent luminescence.…”

“Energy Selection Channels” for High-Performance Electrolyte: Anion-Frenkel Defect Pair as Dominant Source for O Ion Conductions in Pyrochlore-type Lanthanide Hafnium Oxides SOFC

“…With our self-consistent determination process, − as shown in Figure , the Hubbard U parameters are decided to be 2.24 eV for 4f orbitals of La sites and 5.27 eV for 5d orbitals of Hf sites. The O sites within pyrochlore La 2 Hf 2 O 7 have two nonequivalent position, and the Hubbard U parameters of 2p orbitals of O sites were determined as 4.93 and 4.83 eV, respectively.…”

“…In our work, the geometry relaxation of the lattice was performed at PBE+U in DFT through CASTEP codes, which has been proved that is reliable on many f-orbital based oxides . To improve the accuracy of the results of electronic properties, we introduce the recently developed method on ab initio determination of Hubbard U parameters to carefully avoid extra spurious error from orbital self-interactions. − …”