纳米氧化锌颗粒的荧光光谱特性及测试条件的影响

分别用沉淀法和有机物单源的热分解方法从溶液中生长了不同尺寸的氧化锌纳米晶体,研究了纳米晶体的荧光特性及其对测量样品状态的依赖关系.尺寸比较大的ZnO纳米晶体在固态下其荧光光谱为宽阔的发光带,并在宽阔发光带上出现一系列明显的精细结构,而分散于有机溶剂中时其荧光由激子复合发射和通过氧空位的复合发射组成.分散于有机溶剂中的中等尺寸的表面包裹的纳米ZnO晶体的荧光由激子荧光、通过浅杂质的发射和通过本征缺陷复合的荧光组成,其强度随着测量浓度的升高而增强,并且激子的荧光发生红移;尺寸比较小的表面包裹的纳米晶体的荧光为激子复合和通过氧空位复合的荧光组成,激子荧光强度、通过氧空位的发光强度及其相对强度随着纳米晶体浓度的变化而变化,测量浓度的升高,激子发光峰没有位移,但与缺陷态相关的激发光荧光发生红移.

PHOTOLUMINESCENCE OF ZnO NANOPARTICLES

ZnO nanoparticles with different sizes are grown from solution by precipitation and thermolysis of single source precursor.The luminescence of ZnO nanocrystals and its dependence on the sample states are studied.Broadened band with overlapped fine structure are observed in the solid-state nanocrystals of larger size whereas only sharp strong exciton emission and weaker O vacancies related emission are observed when the nanocrystals dissolved in organic solvent.Luminescence from free excitons,near band shallower defects and O vacancies are observed from medium size capped nanocrystals dissolved organic solvent. With the increase of nanocrystal concentration in the solution the intensity of luminescence increases,but the luminescence of free excitons has a red shift.Only emission from excitons and O vacancies is observed in capped nanocrystals with small size dissolved in organic solution,the intensity of emission from excitons,O vacancies and their relative intensity vary with the concentration of nanocrystals in the sovents.With the increase of nanocrystal concentration,the emission from excitons does not shift but the absorption related to emission of O vacancy has a red shift.