Multi-channel electroluminescence of CdTe/CdS core-shell quantum dots implemented into a QLED device

Abstract

CdTe/CdS core-shell quantum dots were synthesized and implemented into a light emitting device resulting in multi-channel electroluminescence with a light-green emission colour. The main electroluminescence band at about 530 nm corresponds to the emission by the CdTe core (type I core/shell structure), while the next emission band at 595 nm is assigned to the crossed recombination of electrons from the conduction band of the CdS shell and holes from the valence band of the CdTe core (type II core/shell structure). At the same time, the photoluminescence spectrum of the synthesized CdTe/CdS core-shell quantum dots contains only one emission band distinctive for type II structures. This behavior of CdTe/CdS core-shell quantum dots upon the electroexcitation allows the extension of the electroluminescence spectrum in the optical region in a way that is useful for the lighting-source applications. Such multi-channel electroluminescence can most probably also be reproduced in related core-shell systems accounting for size-confinement between the core size and shell thickness.

Efficient and Stable CdSe/CdS/ZnS Quantum Rods-in-Matrix Assembly for White LED Application

“…The pristine CdSe QDs have a PLQY of 25% in solution but show strong fluorescent quenching after transferring into dry powder. This is caused by the near-field energy transfer and reabsorption due to the close distance among agglomerated QDs in powder form [40]. In comparison, the CdSe/CdS QRs present a higher PLQY of 42% in solution and a drop of 6% when being transferred into power, indicating that the large volume of CdS shelling effectively inhibits the reabsorption and reduces the fluorescent quenching by enlarging the average distance between CdSe cores and increasing the Stokes shift [41].…”

<p>A Lysosome-Targetable Fluorescence Probe Based on L-Cysteine-Polyamine-Morpholine-Modified Quantum Dots for Imaging in Living Cells</p>

“…Quantum dots (QDs) have range of applications as nano-fluorescent probes and antitumor drug carriers, due to their unique optical properties and electronic structure. [1][2][3][4][5][6] Although QDs have strong fluorescence intensity, long fluorescence lifetime and high light stability, QDs generally have poor water solubility, high toxicity and poor cell targeting ability. [7][8][9][10][11][12][13] It is well known that hydrophobic QDs can be engineered to have great water solubility through surface-exchange of hydrophobic surfactant molecules for hydrophilic ligands.…”

Enhanced photoluminescence quantum yield of red‐emitting CdTe:Gd3+ QDs for WLEDs applications

“…However, the solidification process is usually accompanied by particle agglomeration, which causes PL QY decrease and hinders their applications . In order to improve PL QY of solid QDs, a common method is coating inert materials on CdTe QDs to prevent CdTe core from aggregation and many core‐shell structural composites with enhanced PL QY have been reported . However, the preparation of these composites is quite a complex process with high cost.…”

“…and many core-shell structural composites with enhanced PL QY have been reported. [12][13][14][15][16][17][18][19] However, the preparation of these composites is quite a complex process with high cost. Therefore, another facile method which improves PL QY by ion doping is also attracting more and more attention.…”