Near-Infrared Emitting Colloidal PbS Nanoplatelets: Lateral Size Control and Optical Spectroscopy
作者:Ali Hossain Khan、Rosaria Brescia、Anatolii Polovitsyn、Ilaria Angeloni、Beatriz Martín-García、Iwan Moreels
DOI:10.1021/acs.chemmater.6b05111
日期:2017.4.11
Two dimensional (2D) colloidal PbS nanoplatelets (NPLs) with a thickness of 1.8–2.8 nm have been synthesized using a single-molecule precursor approach with lead octadecylxanthate. The lateral dimensions were tuned by varying the reaction temperature, growth time, and capping ligands. Transmission electron microscopy and X-ray diffraction reveal that the NPLs have an orthorhombic crystal structure rather than the rocksalt phase usually reported for bulk and nanostructured PbS. The 1.8 nm thickness, in combination with the tunable lateral dimensions, results in a blue-shifted absorption peak at 715–730 nm and a 48–68 nm narrow emission spectrum with a surprisingly small, 18 nm Stokes shift at room temperature. The fluorescence lifetime of these PbS NPLs is 2 orders of magnitude shorter than the typical lifetime in 0D colloidal PbS quantum dots, highlighting the advantageous properties of colloidal 2D nanostructures that combine strong transversal with weak lateral confinement.
利用十八烷基黄酸铅的单分子前驱体方法合成了厚度为 1.8-2.8 纳米的二维(2D)胶体 PbS 纳米片(NPLs)。通过改变反应温度、生长时间和封端配体,可以调整横向尺寸。透射电子显微镜和 X 射线衍射显示,NPL 具有正长方晶体结构,而不是通常报道的块状和纳米结构 PbS 的岩盐相。1.8 nm 的厚度加上可调的横向尺寸,使其在室温下具有 715-730 nm 的蓝移吸收峰和 48-68 nm 的窄发射光谱,并具有令人惊讶的 18 nm 斯托克斯偏移。这些 PbS NPL 的荧光寿命比 0D 胶体 PbS 量子点的典型寿命短 2 个数量级,凸显了结合了强横向和弱横向限制的胶体 2D 纳米结构的优势特性。