Lee Jeunghoon, Yang Baocheng, Li Rongfu, Seery Thomas A P, Papadimitrakopoulos Fotios
Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Material Science, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3136, USA.
J Phys Chem B. 2007 Jan 11;111(1):81-7. doi: 10.1021/jp0603841.
Water-soluble CdSe nanocrystal/poly(allylamine) clusters with sizes ranging between 50 and 200 nm were prepared using 3-amino-1-propanol as a compatibilizing agent. Photoluminescence (PL) quantum yields (QY) up to 20% were achieved in water without the need to clad these CdSe nanocrystals (NCs) with higher band gap inorganic layers. The polymer-to-nanocrystal ratio plays an important role in the internal structure and stability of these polymer/NC clusters, as determined by static and dynamic light scattering in conjunction with PL studies. These results were modeled by using an effective-mass approximation and perturbation theory on the change in dielectric constant of the immediate NC environment. The time evolution of the average cluster radius of gyration and hydrodynamic radius revealed that a higher polymer-to-NC ratio leads to increased PL stability and QY. This is a result of a denser cluster configuration, which affords improved NC passivation. Increasing the ionic strength results in greater nanocluster compaction and higher PL QYs. Decreasing the pH value below 12 resulted in dramatic reduction in PL brightness, despite cluster densification, due to partial ionization and dissolution of the amine-based NC surface-capping agents.
以3-氨基-1-丙醇作为增容剂，制备了尺寸在50至200纳米之间的水溶性硒化镉纳米晶体/聚烯丙胺簇。在水中实现了高达20%的光致发光（PL）量子产率（QY），无需用带隙更高的无机层包覆这些硒化镉纳米晶体（NCs）。通过静态和动态光散射结合PL研究确定，聚合物与纳米晶体的比例对这些聚合物/NC簇的内部结构和稳定性起着重要作用。利用有效质量近似和微扰理论对紧邻NC环境的介电常数变化对这些结果进行了建模。平均簇回转半径和流体动力学半径的时间演化表明，较高的聚合物与NC比例导致PL稳定性和QY增加。这是由于簇结构更致密，从而使NC钝化得到改善。增加离子强度会导致纳米簇更加致密且PL QY更高。将pH值降低到12以下，尽管簇致密化，但由于胺基NC表面封端剂的部分电离和溶解，导致PL亮度急剧降低。
