Brightly Luminescent Cu-Zn-In-S/ZnS Core/Shell Quantum Dots in Salt Matrices

Abstract

In the past decades cadmium-free quantum dots (QDs), among which are quaternary colloidal Cu-Zn-In-S/ZnS (CZIS/ZnS) core/shell nanocrystals (NCs), have attracted great scientific interest. Particularly, their low toxicity and the possibility to tune their photoluminescence (PL) properties by varying the composition in the multicomponent system make them highly attractive for applications in light-emitting diodes (LEDs). Thus, the demands for high quality CZIS/ZnS QDs and methods to process them into bulk materials stimulate investigations of these nanomaterials. Herein, we demonstrate the synthesis of CZIS/ZnS core/shell NCs via a surfactant induced nucleation process, which emit in various colors covering the range from 520 nm to 620 nm possessing high photoluminescence quantum yields (PLQYs) up to 47%. Furthermore, the as synthesized NCs were successfully integrated into two different salt matrices [Na2B4O7 (Borax) and LiCl] using two different approaches. The commonly used incorporation of the NCs into Borax salt led to salt crystals emitting from 540 nm to 600 nm with PLQYs up to 24%. By encapsulating the QDs into LiCl, brightly emitting NCs-in-LiCl powders with the PL covering a range from 520 nm to 650 nm with PLQYs of up to 14% were obtained. As a proof of concept, the fabrication of a color conversion LED using NCs encapsulated into LiCl demonstrated the applicability of the encapsulated NCs.

Design of cross-linked polyisobutylene matrix for efficient encapsulation of quantum dots

“…The choice of an appropriate host material and optimization of transferring QDs from the solution to the solid matrix have become an important scientic and technological challenge. Although a number of attempts have been undertaken to nd an optimal matrix for embedding QDs such as ionic crystals, [12][13][14][15][16] silica, 17 metal oxides, 18 or inorganicorganic hybrid materials, 19,20 polymers remain the most appropriate and promising matrices for this application. 21,22 Polymers are attractive as host materials for QDs due to their low cost, simple processing and availability on an industrial scale.…”

Robust Polymer Matrix Based on Isobutylene (Co)polymers for Efficient Encapsulation of Colloidal Semiconductor Nanocrystals

“…The latter is the most important characteristic for application of QDs in LEDs. In order to prevent the degradation of the QD surface, usually they are encapsulated into stable matrices, such as polymers, [12][13][14] silica, [15][16] inorganic salts, [17][18][19][20][21] and metal oxides 22 . Among them, polymer matrices are typically based on polyacrylates 13,[23][24] and polystyrene 12,14 .…”

“…The latter is the most important characteristic for the application of QDs in LEDs. In order to prevent degradation of the QD surface, usually they are encapsulated into stable matrixes, such as polymers, − silica, , inorganic salts, − and metal oxides . Among them, polymer matrixes are typically based on polyacrylates ,, and polystyrene. , However, most of these polymers still exhibit remarkable permeability for gases, especially for oxygen.…”

Synthesis of InP/ZnS Nanocrystals and Phase Transfer by Hydrolysis of Ester

“…Generally, they can be divided in wet chemical preparation (in organic solvent e.g. hot-injection [9][10][11] or heating-up [12], in aqueous solvent e.g. by chemical precipitation [13][14][15][16]), solid-state preparation (e.g.…”

“…They can be, e.g. dot-in-rod shaped CdSe/CdS [1], CdSe/ ZnS [26] or spherical core-shell NCs like CdSe/ZnS [4], InP/ZnS [5,27,28], Cu-Zn-In-S/ZnS [11]. This enables the possibility to protect the particle cores from e.g.…”