Zone-folded longnitude acoustic phonons driving self-trapped state emission in colloidal CdSe nanoplate superlattice

Lattice dynamics of quasi-two-dimensional CdSe nanoplatelets and their Raman and infrared spectra

Phonon spectra of CdSe nanoplatelets (2-6 ML) with the zinc-blende structure were calculated from first principles within the density-functional theory. It turned out that the Lamb modes in nanoplatelets are in fact optical rather than acoustic vibrations. Phonon spectra of the nanoplatelets show the appearance of a large number of low-frequency modes inherited from TA phonons in bulk CdSe. Calculations of the Raman spectra indicate a need to revise the interpretation of available experimental data. The largest contribution to the Raman spectra is provided by the quasi-Lamb modes with the $A_1…

CdSe Colloidal Quantum Rings

Atomically flat semiconductor nanostructures have sharp photoluminescence emission, short radiative lifetimes and a well-defined planar structure. However, these nanostructures lack the optical and electronic fine-tuning that justify extensive research in colloidal quantum dots. Here, we propose a heterostructure based on CdS nanoplatelets with laterally grown CdSe. Samples of two different thickness and varying ring width are synthesized by a one-pot method during which CdSe ring width is controlled by Se precursor amount. The CdSe dimensionality is continuously tuned from a 0D array of CdSe …

Lateral quantum confinement regulates charge carrier transfer and biexciton interaction in CdSe/CdSeS core/crown nanoplatelets

Charge carrier dynamics essentially determine the performance of various optoelectronic applications of colloidal semiconductor nanocrystals. Among them, two-dimensional nanoplatelets provide new adjustment freedom for their unique core/crown heterostructure. Herein, we demonstrate that by fine-tuning the core size and the lateral quantum confinement, the charge carrier transfer rate from the crown to the core can be varied by one order of magnitude in CdSe/CdSeS core/alloy-crown nanoplatelets. In addition, the transfer can be affected by a carrier blocking mechanism, i.e., the filled carriers…

Raman and infrared studies of CdSe/CdS core/shell nanoplatelets

The vibrational spectroscopy of semiconductor nanostructures can provide important information on their structure. In this work, experimental Raman and infrared spectra are compared with vibrational spectra of CdSe/CdS core/shell nanoplatelets calculated from first principles using the density functional theory. The calculations confirm the two-mode behavior of phonon spectra of nanostructures. An analysis of the experimental spectra reveals the absence of modes with a high amplitude of vibrations of surface atoms, which indicates their strong damping. Taking into account the difference in the…

由两个Bragg反射器组成的微腔中己烷分散的胶体CdSe纳米片在室温下的强耦合

Room-temperature strong coupling of hexane-dispersed colloidal CdSe nanoplatelets in a microcavity composed of two Bragg reflectors

本文报告了含己烷分散胶体CdSe纳米片的半波长平面微腔的制备与光学表征，在室温下实现了53.5 meV真空Rabi分裂的强光物质耦合，并通过单激子态耦合模型直观定量地解释了微腔的反射率与光致发光特性。

First-principles calculations of vibrational spectra of CdSe/CdS superlattices

The vibrational spectra of CdSe/CdS superlattices (SLs) with different layer thicknesses are calculated from first principles within the density functional theory. It is shown that, along with folded acoustic and confined optical modes, a number of confined acoustic modes appear in SLs. In structures with a minimum thickness of one of the layers, microscopic interface modes similar to local and gap modes in crystals appear. An analysis of projections of the eigenvectors of vibrational modes in SLs onto the orthonormal basis of normal modes in binary compounds enables to establish the details o…