CdZnSe/ZnSeS/CdZnS红光量子点的合成及其在发光二极管中的应用

The Synthesis of CdZnSe/ZnSeS/CdZnS Red-Emitting Quantum Dot and Its Application in Light-Emitting Diode

摘要:

为实现高荧光量子产率和较浅价带的量子点，选用镉掺硫化锌（CdZnS）和硫掺杂硒化锌（ZnSeS）分别为最外层壳和内层壳，合成了核/壳结构为CdZnSe/ZnSeS/CdZnS的红光量子点。结果表明：内部ZnSeS壳层能有效地将激子限制在量子点的核心内，与CdZnSe核和CdZnS外层壳间晶格匹配较小，使量子点具有完美的纳米结构和高光致发光量子产率；CdZnS最外壳层能够调控量子点的价带，减小空穴从聚合物到量子点之间的注入能垒，有利于空穴从空穴传输层注入到红光量子点发光层，实现量子点发光二极管中载流子平衡的复合；基于这些新型量子点的红色量子点发光二极管的最大外部量子效率为18.5%，量子点发光二极管在低外加电压下表现出较高的亮度值，具有较高的功率效率。基于CdZnS壳层的量子点具有较高的光致发光量子产率和较浅的价带能级，其可作为一种极好的最外层壳，以实现高性能的量子点发光二极管。

Abstract:

In order to achieve the quantum dots with high photoluminescence quantum yield and shallow valence band， a new red-emitting quantum dot with a core/shell structure of CdZnSe/ZnSeS/CdZnS is synthesized by using a cadmium-doped zinc sulfide （CdZnS） as an outermost shell and S-doped zinc selenide （ZnSeS） as an inner shell. Firstly， the inner ZnSeS shell confined the excitons inside the core of quantum dot and provided a better lattice match with the core and outermost shell. It resulted in a perfect nanostructure of quantum dot and hence a high photoluminescence quantum yield. Secondly， the valence band of quantum dot can be managed by using the outermost CdZnS shell so as to decrease the energy barrier for hole injection from a hole transport polymer to a quantum dot emitting layer. As a result， the CdZnS shell was in favour of the hole injection from the hole transport layer to the quantum dot emitting layer， achieving a balanced recombination of carriers in quantum dot-based light-emitting diode. Therefore， the quantum dot-based light-emitting diode made by the new quantum dot exhibited a peak external quantum efficiency of 18.5%. In addition， It also had an unexpected brightness at low applied voltages and hence a high power efficiency. Thus， CdZnS can be used as an excellent outermost shell to achieve high performance quantum dot-based light-emitting diode due to that it affords its quantum dot with the feature of high photoluminescence quantum yield and shallow valence band energy level.