ZnO_PVA_luminescence_spectroscopy_TSNUK

Zinc oxide nanoparticles were successfully synthesized in polyvinyl alcohol (PVA) media using a modified co-precipitation method and a green chemistry approach. Single-phase ZnO samples with wurtzite structure were formed already at 400 °C. The polymer media forms agglomerating clouds around the ZnO nanoparticles. Average nanoparticle size has tendency to decrease with the PVA content. Visible photoluminescence and radioluminescence emission spectra of the pure ZnO and ZnO-xPVA revealed strong differences. The spectra of pure ZnO samples contains components at 385 and 510 nm corresponded to excitonic and defect-related emission, respectively. Spectra of the ZnO-xPVA samples are dominated by a band peaked in the red spectral region. This band consists of two components at 630 and 720 nm which are assigned to recombination transitions from Zni and Hi to Oi defect energy levels, respectively. These results demonstrate that luminescence of ZnO can be tailored by manipulating defect configurations, even without high-temperature processing本研究采用改良共沉淀法结合绿色化学路径，成功在聚乙烯醇（polyvinyl alcohol, PVA）介质中合成氧化锌（ZnO）纳米颗粒。仅在400℃下即可制备出具有纤锌矿结构（wurtzite structure）的单相氧化锌样品。该聚合物介质会在氧化锌纳米颗粒周围形成团聚状包覆结构。纳米颗粒的平均粒径随PVA含量升高呈现降低趋势。纯氧化锌与ZnO-xPVA样品的可见光光致发光（photoluminescence）及辐射发光（radioluminescence）发射光谱存在显著差异。纯氧化锌样品的光谱包含385nm与510nm处两个特征峰，分别对应激子（exciton）发光与缺陷相关发光。ZnO-xPVA样品的光谱则以红光波段的特征发射峰为主，该发射带包含630nm与720nm处两个组分，分别对应锌间隙原子（Zni）与氢间隙原子（Hi）向氧间隙原子（Oi）缺陷能级的复合跃迁。上述结果表明，即便无需高温处理，通过调控缺陷构型即可实现氧化锌发光性能的定制化调控。