液晶-氧化锌纳米复合材料的可调发光

Tunable Emission Colours from Liquid Crystal/ZnO Nanocomposites

采用超声波分散技术,选用氧化锌纳米晶体和液晶(N-(4-methoxybenzylidene)-4-ethoxybenzenamine),制成液晶质量分数分别为10%、20%、30%、40%、50%、60%、70%、80%的液晶-氧化锌纳米复合材料。通过X射线衍射仪、透射电子显微镜、光致发光光谱仪对样品进行表征。实验结果表明:当液晶MB2BA在氧化锌纳米晶体的质量分数从0增加到80%时,氧化锌纳米复合材料的PL光谱峰值最终移到了418 nm的蓝光区域。随着氧化锌纳米晶体中液晶分子的增加,氧化锌纳米晶体的表面缺陷减少、其深层发光明显削弱,氧化锌纳米晶体的光致发光可以由最初的黄绿色转变为蓝色。因此,可以在氧化锌纳米晶体中通过添加适量的液晶MB2BA来实现蓝光发射。

MB 2BA/ZnO nanocomposites with different mass fraction of liquid crystal N-(4-methoxybenzylidene)-4-ethoxybenzenamine(MB 2BA)were successfully prepared by ultrasonic dispersing technology.The prepared MB 2BA/ZnO nanocomposites were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM)and photoluminescence(PL)spectroscopy,respectively.The experimental results show that the UV emission of ZnO nanocrystals and PL of the MB 2BA is about to form a blue emission band with its peak located at about 418 nm when the concentration of MB 2BA in ZnO is up to 80%.By increasing the concentration of MB 2BA in ZnO nanocrystals,deep-level luminescence obviously weakened with reducing the surface defects of the ZnO nanocrystals,and the originally yellow-green photoluminescence of the ZnO nanocrystals can be tuned to blue.Our results demonstrate that the blue colored photoluminescence can be achieved by mixing appropriate amount of MB 2BA with ZnO nanocrystals.