聚乙烯吡咯烷酮
纳米颗粒
成核
吸附
钝化
材料科学
吸收(声学)
化学工程
光致发光
锌
光化学
费斯特共振能量转移
激子
聚合物
荧光
纳米技术
化学
图层(电子)
物理化学
高分子化学
有机化学
光电子学
工程类
复合材料
冶金
物理
量子力学
作者
Hasan Kurt,Ece Alpaslan,Burçin Yıldız,Alpay Taralp,Cleva W. Ow‐Yang
标识
DOI:10.1016/j.jcis.2016.11.017
摘要
Homopolymers, such as polyvinylpyrrolidone (PVP), are commonly used to passivate the surface of blue-light emitting ZnO nanoparticles during colloid nucleation and growth. However, although PVP is known to auto-fluoresce at 400nm, which is near the absorption edge of ZnO, the impact of PVP adsorption characteristics on the surface of ZnO and the surface-related photophysics of PVP-capped ZnO nanoparticles is not well understood. To investigate, we have synthesized ZnO nanoparticles in solvents containing PVP of 3 concentrations-0.5, 0.7, and 0.11gmL-1. Using time-domain NMR, we show that the adsorbed polymer conformation differs with polymer concentration-head-to-tail under low concentration (e.g., 0.05gmL-1) and looping, then train-like, with increasing concentration (e.g., 0.07gmL-1 and 0.11gmL-1, respectively). When the surface-adsorbed PVP is entrained, the surface states of ZnO are passivated and radiative emission from surface trap states is suppressed, allowing emission to be dominated by exciton transitions in the UV (ca. 310nm). Moreover, the reduced proximity between the PVP molecule and the ZnO gives rise to increased efficiency of energy transfer between the exciton emission of ZnO and the HOMO-LUMO absorption of PVP (ca. 400nm). As a result, light emission in the blue is enhanced in the PVP-capped ZnO nanoparticles. We thus show that the emission properties of ZnO can be tuned by controlling the adsorbed PVP conformation on the ZnO surface via the PVP concentration in the ZnO precipitation medium.
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