论文标题
在超薄PBS纳米板中探测激子，并具有增强的近红外发射
Probing Excitons in Ultrathin PbS Nanoplatelets with Enhanced Near-Infrared Emission
论文作者
论文摘要
强烈的量子限制的2D胶体PBS纳米平板电脑（NPLS）是近红外光电应用的非常有趣的材料。在这里，我们使用超快的瞬态光吸收光谱来研究具有立方（岩石）结构的超薄PBS NPL中光激发激子的特征和动力学。 NPL在铅Oleate和Thiourea前体的接近室温下合成，并在680 nm（1.8 eV）以及720 nm（1.7 eV）处显示光吸收发作以及光致发光。通过在合成后步骤中用CDCL2处理PBS NPL，它们的光致发光量子产率从1.4％升至19.4％。表面处理导致结构中硫比的增加，并导致相关的非辐射重组。原始和CDCL2中的激子相互作用以1.8和2.2 TH的频率处理了PBS NPL，从测得的瞬态吸收光谱中的相干振荡中可以明显看出。这项研究是揭开和控制IV-VI半导体NPL的光学特性的重要一步。
Strongly quantum-confined 2D colloidal PbS nanoplatelets (NPLs) are highly interesting materials for near-infrared optoelectronic applications. Here, we use ultrafast transient optical absorption spectroscopy to study the characteristics and dynamics of photoexcited excitons in ultrathin PbS NPLs with a cubic (rock-salt) structure. The NPLs are synthesized at near room temperature from lead oleate and thiourea precursors and show an optical absorption onset at 680 nm (1.8 eV) as well as photoluminescence at 720 nm (1.7 eV). By treating PbS NPLs with CdCl2 in a post-synthetic step, their photoluminescence quantum yield is strongly enhanced from 1.4 % to 19.4 %. The surface treatment leads to an increased lead to sulfur ratio in the structures and associated reduced non-radiative recombination. Exciton-phonon interactions in pristine and CdCl2 treated PbS NPLs at frequencies of 1.8 and 2.2 THz are apparent from coherent oscillations in the measured transient absorption spectra. This study is an important step forward in unraveling and controlling the optical properties of IV-VI semiconductor NPLs.
