Sanderson William M, Hoy Jessica, Morrison Calynn, Wang Fudong, Wang Yuanyuan, Morrison Paul J, Buhro William E, Loomis Richard A
Department of Chemistry and Institute of Materials Science and Engineering, Washington University in St. Louis, One Brookings Drive, CB 1134, Saint Louis, Missouri 63130, United States.
J Phys Chem Lett. 2020 May 7;11(9):3249-3256. doi: 10.1021/acs.jpclett.0c00489. Epub 2020 Apr 13.
The excitation energy dependence (EED) of the photoluminescence quantum yield (Φ) of semiconductor nanoparticles with varying dimensionalities is reported. Specifically, the EEDs of CdSe quantum dots, CdSe quantum platelets, CdSe quantum belts, and CdTe quantum wires were determined via measurements of individual Φ values and photoluminescence efficiency (PL()) spectra. There is a general trend of overall decreasing efficiency for radiative recombination with increasing excitation energy. In addition, there are often local minima in the PL() spectra that are most often at energies between quantum-confinement transitions. The average PL lifetimes of the samples do not depend on the excitation energy, suggesting that the EED of Φ arises from charge carrier trapping that competes efficiently with intraband carrier relaxation to the band edge. The local minima in the PL() spectra are attributed to excitation into optically coupled states that results in the loss of carriers in the semiconductor. The EED data suggest that the PL() spectra depend on the sample synthesis, preparation, surface passivation, and environment.
报道了具有不同维度的半导体纳米颗粒的光致发光量子产率（Φ）的激发能量依赖性（EED）。具体而言，通过测量单个Φ值和光致发光效率（PL()）光谱，确定了CdSe量子点、CdSe量子片、CdSe量子带和CdTe量子线的EED。随着激发能量的增加，辐射复合效率总体上呈现下降趋势。此外，PL()光谱中通常存在局部最小值，这些最小值最常出现在量子限制跃迁之间的能量处。样品的平均PL寿命不依赖于激发能量，这表明Φ的EED源于电荷载流子捕获，其与带内载流子弛豫到带边的过程有效竞争。PL()光谱中的局部最小值归因于激发到光学耦合态，这导致半导体中载流子的损失。EED数据表明，PL()光谱取决于样品的合成、制备、表面钝化和环境。
