The luminescence of nanocrystalline ZnO particles: the mechanism of the ultraviolet and visible emission
The luminescence of nanocrystalline ZnO particles: the mechanism of the ultraviolet and visible emission
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DOI：
10.1016/s0022-2313(99)00482-2
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发表时间：
2000-05
影响因子：
3.6
通讯作者：
A. V. Dijken;E. Meulenkamp;D. Vanmaekelbergh;A. Meijerink
中科院分区：
文献类型：
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作者：
A. V. Dijken;E. Meulenkamp;D. Vanmaekelbergh;A. Meijerink
本文介绍了不同尺寸纳米晶氧化锌悬浮液的稳态发光测量结果。在所有情况下都观察到两个发射带。一个是紫外的激子发射带，第二个是可见光的强而宽的发射带，相对于吸收开始位移约1.5eV。随着粒子尺寸的增大，可见发射强度减小，而激子发射强度增大。根据前人的研究结果，提出了一个模型，该模型将可见光发射归因于靠近导带边缘的能级上的电子与ZnO粒子体（V⋅⋅O）中的深捕获空穴的辐射复合。通过两步过程将光生空穴从价带转移到粒子体的V·Olevel能级的模型，解释了可见光与激子发光强度比的大小依赖性和动力学。这个过程的第一步是有效的表面捕获，可能是在O2 -位点。
Results of steady-state luminescence measurements performed on suspensions of nanocrystalline ZnO particles of different sizes are presented. In all cases two emission bands are observed. One is an exciton emission band in the UV and the second an intense and broad emission band in the visible, shifted by approximately 1.5eV with respect to the absorption onset. As the size of the particles increases, the intensity of the visible emission decreases, while that of the exciton emission increases. In accordance with previous results, a model is presented in which the visible emission is assigned to the radiative recombination of an electron from a level close to the conduction band edge and a deeply trapped hole in the bulk (V⋅⋅O) of the ZnO particle. The size dependence of the intensity ratio of the visible to exciton luminescence and the kinetics are explained by a model in which the photogenerated hole is transferred from the valence band to a V⋅Olevel in the bulk of the particle in a two-step process. The first step of this process is an efficient surface-trapping, probably at an O2−site.