液相合成方形PbS纳米晶的光学特性

采用一种简单、温和的液相合成方法制备了PbS纳米晶，利用透射电镜和高分辨透射电镜对PbS纳米晶的形貌与晶型结构进行了表征．研究了PbS纳米晶的光学吸收和光致发光特性，并比较分析了包覆剂聚乙烯吡咯烷酮(PVP)和回流时间对产物光学特性的影响．结果表明：PVP分子链中的O原子与纳米晶表面吸附的游离态Pb原子形成Pb-O配位键，使产物的激子吸收大为减弱，同时引起了表面浅束缚态能量的升高，最终导致了荧光淬灭现象．

The unique optical characteristics of cubic PbS nanocrystals synthesized by a mild solution phase route

PbS nanocrystals were prepared via a convenient and mild solution phase route. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) were used to characterize morphology and the phase structure of the as-obtained PbS nanocrystals. The absorption spectra and photoluminescent characteristics of the noncapped PbS nanocrystals was be observed at room temperature. In addition, the influence of capping agent (polyvinylpyrrolidone PVP) and refluxing time was also investigated. The results demonstrated that the oxygen atoms of PVP coordinating with the 3d orbits of Pb atoms attached to the nanocrystals surfaces would result in the exciton absorption bleaching of PVP-capped PbS nanocrystals. At the same time, it would provide shallower surface recombination sites and furthermore lead to photoluminescence quenching.