The photoluminescence from solid-state ZnO nanoparticles (NPs) assemblies was studied as a function of the number on NPs in the assembly. With increasing number of NPs, the UV emission band broadened and redshifted, while the UV/visible emission rate ratio decreased. Furthermore, while samples with few NPs displayed a typical linear dependence for the UV emission rate as a function of the excitation power, samples with large number of deposited NPs showed unusual non-linear, nonmonotonic dependences with maxima at intermediate excitation powers. Also, for samples with large number of NPs, the UV band became broader as the excitation power was increased. These unusual results can be understood by considering the interplay between photon self-absorption effects, interface trap states between NPs and illumination power dependent potential barriers at NP/NP interfaces. The exposure of samples with large number of NPs to ethanol vapor during the photoluminescence measurements resulted in partial removal of the non-monotonic behavior of the UV emission rate dependence on excitation power.

研究了固态ZnO纳米颗粒（NPs）组件的光致发光与组件中NPs数量的关系。随着NP数量的增加，UV发射带变宽并发生红移，而UV /可见发射率之比下降。此外，虽然具有少量NP的样品显示出典型的UV发射速率线性相关性，而它是激发功率的函数，但是具有大量沉积的NP的样品却显示出异常的非线性，非单调性相关性，并且在中间激发功率下具有最大值。同样，对于具有大量NP的样品，随着激发功率的增加，UV谱带变得更宽。通过考虑光子自吸收效应之间的相互作用，可以理解这些异常结果。NP之间的界面陷阱状态和NP / NP界面上与照明功率有关的势垒。在光致发光测量过程中，具有大量NP的样品暴露于乙醇蒸气中，导致部分消除了依赖于激发功率的UV发射速率的非单调行为。