前驱物[S^(2-)]/[Pb_(2+)]摩尔比对PbS纳米晶红外发光光谱的影响

Effect of precursor molar ratio of [S^(2-)]/[Pb^(2+)] on infrared spectrum of PbS nanocrystals

采用水溶性前驱物在乙醇介质中制备了不同[S2-]/[Pb2+]摩尔比例的PbS纳米晶,利用X射线衍射(XRD)、透射电子显微镜(TEM)、紫外-可见吸收光谱(Abs)、光致发光谱(PL)对所制备PbS纳米晶的晶体结构、纳米晶粒径、形貌以及能带结构和发光特性进行了表征,结果表明:随着前驱物[S2-]/[Pb2+]摩尔比例的提高,PbS纳米晶颗粒尺寸从3.9 nm增大到5.9 nm,发光峰值位置从1 009 nm移动到1 486 nm。通过拟合[S2-]/[Pb2+]=0.5条件下PbS纳米晶平均粒径对时间变化曲线,发现该方法下PbS纳米晶所经历的生长机制为Ostwald成熟化。运用经典纳米晶扩散控制生长模型,解释了实验中随着[S2-]/[Pb2+]的提高对溶液中纳米晶生长速率的影响。

PbS nanocrystals with different precursor molar of /[Pb 2 ＋ ] were prepared in alcohols medium from water-solubility precursors.The crystal structure,average particle size,morphology and luminescence properties of as-synthesized products were characterized by X-ray diffraction（XRD） spectra, transmission electron microscope（TEM） images,ultraviolet-visible（UV-VIS） absorption spectra and photoluminescence（PL） spectra.The XRD patterns show that the average particle size of the samples is calculated to be increased from 3.9 nm to 5.9 nm with the /[Pb 2 ＋ ] molar ratio enhanced.The PL emission peak position is red-shifted from 1 009 nm to 1 486 nm.The influence of different /[Pb 2 ＋ ] molar ratios on growth rate of PbS nanocrystals was discussed and the growth mechanism was thought to be the diffusion-controlled growth model via Ostwald ripening.