Effect of Correlation and Dielectric Confinement on 1S_1/2^(e)nS_3/2^(h) Excitons in CdTe/CdSe and CdSe/CdTe Type-II Quantum Dots

Abstract

We calculate correlated exciton states in type-II core/shell quantum dots (QDs) using a configuration interaction method combined with the k·p theory. We map the 1S 1/2 (e) 1S 3/2 (h) and 1S 1/2 (e) 2S 3/2 (h) exciton correlation energy relative to the strong confinement approximation as a function of core radius, shell thickness, and dielectric confinement. The type-II confinement potentials enhance the effect of dielectric confinement which can significantly affect the wave functions and exciton energies in such heterostructures. Dielectric confinement mainly increases the correlation energy for QDs in which the corresponding single-particle hole states are delocalized. We also find that correlation leads to large changes in the optical dipole matrix element, particularly for the lowest CdSe/CdTe QD exciton, in the presence of dielectric confinement. We conclude that dielectric confinement affected the exciton properties in CdSe/CdTe QDs more than in CdTe/CdSe QDs due to the band alignment which encourages holes to localize in the shell.

All-order correlation of single excitons in nanocrystals using ak·penvelope-function approach: Application to lead halide perovskites

“…We are interested here in studying such a confined exciton to all orders in the Coulomb interaction g 12 . As a first step, we consider CI in the space of all single-exciton states [12,[14][15][16]. In this approach, a general correlated exciton state e h and correspond (in order) to the five terms in Eq.…”

“…In this paper, we revisit the question of correlated single excitons in the context of inorganic lead-halide perovskite NCs. A commonly used approach to compute exciton properties in NCs is configuration interaction (CI) [12,[14][15][16]. Quantum Monte Carlo has also been used [15].…”

Full-color-emitting (CuInS2)ZnS-alloyed core/shell quantum dots with trimethoxysilyl end-capped ligands soluble in an ionic liquid

“…The overcoating of fluorescent mc-NCs with semiconductors of higher band-gap energy is a common way to minimize the non-radiative transitions caused by surface defect trapping to enhance the PL intensity. 22 Here, batch feeding approach was followed for the core growth to deposit a ZnS shell around the ZCIS core NCs with designed layers, which also induced a blue shift as reported and was beneficial in widening the PL range of the ZCIS/ZnS core/shell QDs to provide tunable photoluminescence (PL) emission property.…”

High-Efficiency CdSe Quantum Dots/Fe3O4@MoS2/S2O82– Electrochemiluminescence System Based on a Microfluidic Analysis Platform for the Sensitive Detection of Neuron-Specific Enolase

“…Finally, the highly integrated portable chips prepared based on the above strategy were applied to the detection of NSE, which displayed good sensitivity. Quantum dots (QDs) have different physical and chemical properties from conventional nanomaterials because of their obvious quantum size effect, 18 surface effect, 18 dielectric confinement effect, 19 and quantum tunnel effect. 20 As cadmium-based QDs, CdSe QDs have highly asymmetric internal variable structures 21,22 and many ideal optical properties, such as sub thermal room temperature linewidth, spectral diffusion suppression, and high photoluminescence quantum yield, which promote the application of CdSe QDs in ECL.…”