Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University (BUAA), Beijing, 100191, China.
Nanoscale. 2017 Nov 2;9(42):16420-16428. doi: 10.1039/c7nr06564g.
AlO/ZnO, AlO/TiO, TiO/ZnO and MgO/ZnO nanolaminates (NLs) were prepared using atomic layer deposition to explore the dependence of luminescence characterization on the sublayer width and constituents. When the ZnO sublayer width is larger than the Bohr radius in AlO/ZnO NLs, the UV luminescence arising from ZnO is reduced and even quenched with decreasing the ZnO width due to the nonradiative recombination (NR) caused by the existence of interface states, while for the ZnO width smaller than the Bohr radius, a visible luminescence rather than UV emission is observed and further enhanced with decreasing the ZnO width. It is also found that the visible luminescence needs a certain width of AlO and is extinguished by the replacement of AlO with TiO. A theoretical model based on the configuration coordination and quantum confinement effect is proposed to understand the physical origin underlying the intriguing optical behaviour. The mechanism has generality and is applicable for other NLs as well, such as AlO/TiO and MgO/ZnO NLs with ultra-thin sublayers in which similar luminescence enhancements are also observed. This work may provide a promising approach for realizing high performance luminescence with various wavelengths for electro- and photo-luminescence applications in NLs.
AlO/ZnO、AlO/TiO、TiO/ZnO 和 MgO/ZnO 纳米多层膜（NLs）通过原子层沉积法制备，以研究发光特性对亚层宽度和组成的依赖关系。当 ZnO 亚层宽度大于 AlO/ZnO NLs 中的玻尔半径时，由于界面态的存在导致非辐射复合（NR），ZnO 的紫外发光会随着 ZnO 宽度的减小而减少甚至猝灭，而对于 ZnO 宽度小于玻尔半径的情况，则观察到可见发光而不是紫外发射，并且随着 ZnO 宽度的减小进一步增强。还发现，可见发光需要一定宽度的 AlO，并且用 TiO 取代 AlO 会使其熄灭。提出了一个基于结构配位和量子限制效应的理论模型，以理解这种有趣的光学行为的物理起源。该机制具有普遍性，也适用于其他具有超薄亚层的 NLs，例如 AlO/TiO 和 MgO/ZnO NLs，其中也观察到类似的发光增强。这项工作为实现具有各种波长的高性能发光提供了一种有前途的方法，可用于 NLs 中的电致发光和光致发光应用。
