Blue Luminescence of ZnO Nanoparticles Based on Non-Equilibrium Processes: Defect Origins and Emission Controls
Blue Luminescence of ZnO Nanoparticles Based on Non-Equilibrium Processes: Defect Origins and Emission Controls
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基于非平衡过程的 ZnO 纳米颗粒蓝色发光：缺陷起源和发射控制
DOI：
10.1002/adfm.200901884
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发表时间：
2010-02-22
影响因子：
19
通讯作者：
Cai, Weiping
中科院分区：
文献类型：
--
作者：
Zeng, Haibo;Duan, Guotao;Cai, Weiping
通过非平衡过程将高浓度的缺陷引入纳米ZnO中，并对由此产生的蓝光发射进行了全面分析，重点关注缺陷的来源和广泛的控制。一些ZnO纳米颗粒表现出非常强的蓝色发射，其强度随着退火而先增加然后减少。这些可见光发射表现出强烈而有趣的激发依赖性：1）蓝色发射的最佳激发能量接近带隙能量，但有效激发可以明显更低，甚至420 nm（2.95 eV < E-g = 3.26 eV）;相比之下，绿色发射只能由大于带隙能量的能量激发;（2）在蓝波段有几个固定的发射波长，分别为415、440、455和488 nm，在不同的激发和退火条件下，这些波长具有相当的稳定性。提出了ZnO的蓝光发射机制，并以与锌相关的缺陷能级为初始态。EPR谱揭示了样品中间隙锌占主导地位，以及间隙锌和氧空位共存的演化过程。此外，实现了可见光发射的良好可控性，包括蓝色和绿色发射的共发射以及从蓝色到黄色的峰值调节。
High concentrations of defects are introduced into nanoscale ZnO through non-equilibrium processes and resultant blue emissions are comprehensively analyzed, focusing on defect origins and broad controls. Some ZnO nanoparticles exhibit very strong blue emissions, the intensity of which first increase and then decrease with annealing. These visible emissions exhibit strong and interesting excitation dependences: 1) the optimal excitation energy for blue emissions is near the bandgap energy, but the effective excitation can obviously be lower, even 420 nm (2.95 eV < E-g = 3.26 eV); in contrast, green emissions can be excited only by energies larger than the bandgap energy; and, 2) there are several fixed emitting wavelengths at 415, 440, 455 and 488 nm in the blue wave band, which exhibit considerable stability in different excitation and annealing conditions. Mechanisms for blue emissions from ZnO are proposed with interstitial-zinc-related defect levels as initial states. EPR spectra reveal the predominance of interstitial zinc in as-prepared samples, and the evolutions of coexisting interstitial zinc and oxygen vacancies with annealing. Furthermore, good controllability of visible emissions is achieved, including the co-emission of blue and green emissions and peak adjustment from blue to yellow.