講演情報
[10a-PA3-8]First-Principles Investigation of Defect Luminescence in ZnO Mechanoluminescent Materials
〇(D)guangfa yang1, Reona Omori1, Tomoki Uchiyama1, Ying Chen1, Xu-Guang Zheng1,2, Chao-Nan Xu1 (1.Tohoku University, 2.Saga University)
キーワード：
Mechanoluminescence、ZnO、First-Principles Investigation
1. Introduction
We have recently demonstrated that alkali-doped ZnO exhibits strong near-infrared mechanoluminescence in the first biological window (650–900 nm) without any rare-earth activator. Here we report first-principles calculations that establish the defect-level origins of the radiative center, carrier trap and mechanoluminescence mechanism.
2. Methods
Calculations were performed using VASP within the GGA+U framework (U(Zn-3d) = 10 eV, U(O-2p) = 7 eV) on a 4×4×2 wurtzite supercell with one Zn atom substituted by Li or Na. Optical transition energies were estimated from the configuration-coordinate (CC) model accounting for lattice relaxation in both ground and excited defect states.
3. Results
Radiative center. The zinc vacancy VZn is identified as the principal near-infrared radiative center. The CC model yields a calculated emission energy of ~1.68 eV (~738 nm), in good agreement with the experimental photoluminescence peak near 750 nm. .
Carrier trap and defect levels. The NaZn–VOcoupled defect state lies ~1.3 eV below the conduction band, consistent with experimental thermoluminescence peaks near 1.15 and 1.36 eV.
We have recently demonstrated that alkali-doped ZnO exhibits strong near-infrared mechanoluminescence in the first biological window (650–900 nm) without any rare-earth activator. Here we report first-principles calculations that establish the defect-level origins of the radiative center, carrier trap and mechanoluminescence mechanism.
2. Methods
Calculations were performed using VASP within the GGA+U framework (U(Zn-3d) = 10 eV, U(O-2p) = 7 eV) on a 4×4×2 wurtzite supercell with one Zn atom substituted by Li or Na. Optical transition energies were estimated from the configuration-coordinate (CC) model accounting for lattice relaxation in both ground and excited defect states.
3. Results
Radiative center. The zinc vacancy VZn is identified as the principal near-infrared radiative center. The CC model yields a calculated emission energy of ~1.68 eV (~738 nm), in good agreement with the experimental photoluminescence peak near 750 nm. .
Carrier trap and defect levels. The NaZn–VOcoupled defect state lies ~1.3 eV below the conduction band, consistent with experimental thermoluminescence peaks near 1.15 and 1.36 eV.