High-efficiency, deep blue ZnCdS/CdxZn1-xS/ZnS quantum-dot-light-emitting devices with an EQE exceeding 18%
High-efficiency, deep blue ZnCdS/CdxZn1-xS/ZnS quantum-dot-light-emitting devices with an EQE exceeding 18%
复制标题
高效率，%20deep%20blue%20ZnCdS/CdxZn1-xS/ZnS%20量子点发光%20devices%20with%20an%20EQE%20exceeding%2018%
DOI：
10.1039/c7nr09175c
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发表时间：
2018-03-28
期刊：
影响因子：
6.7
通讯作者：
Li, Lin Song
中科院分区：
文献类型：
--
作者：
Wang, Ouyang;Wang, Lei;Li, Lin Song
我们报道了一种简便和稳健的ZnCdS核/壳量子点（QD）的合成厚CdxZn 1-xS（x =常数）均匀合金作为中间壳，可以提供有效的限制激子内的ZnCdS核心和crossZnS最外层的壳，以提高稳定性，在相对较高的温度下外延生长。所得的ZnCdS/CdxZn 1-xS/ZnS核/壳量子点具有高的光致发光量子产率（接近100%）和高的色纯度（半峰全宽（FWHM）< 18 nm）。更重要的是，与ZnCdS/ZnS核壳量子点相比，ZnCdS/CdxZn 1-xS/ZnS核壳量子点具有良好的化学/光化学稳定性和更有效的载流子传输性能。将ZnCdS/ZnS和ZnCdS/CdxZn 1-xS/ZnS两种类型的量子点作为发射层并入溶液处理的基于混合量子点的发光器件结构中。我们发现CdxZn 1-xS壳层的存在对器件的外量子效率和电流效率等性能产生了深远的影响。相应的发光二极管表现出超过18%的高EQE，3.4cd A（-1）的峰值电流效率和低效率滚降。基于ZnCdS/CdxZn 1-xS/ZnS的QLED的如此优异的结果可能归因于QD的高PL QY和非常薄的ZnS最外层，其没有牺牲QLED中的电荷注入效率。
We report a facile and robust synthesis of ZnCdS core/shell quantum dots (QDs) with thick CdxZn1-xS(x = constant) uniform alloys as an intermediate shell which can provide effective confinement of excitons within the ZnCdS cores and ultrathin ZnS outermost shell to improve the stability by epitaxial growth at a relatively high temperature. The resulting nearly monodisperse ZnCdS/CdxZn1-xS/ZnS core/shell QDs have high photoluminescence quantum yield (near to 100%) and high color purity (full width at half maximum (FWHM) < 18 nm). More importantly, the ZnCdS/CdxZn1-xS/ZnS core/shell QDs have good chemical/photochemical stability and more efficient carrier transport performance compared with ZnCdS/ZnS core/shell QDs. Two types of QDs of ZnCdS/ZnS and ZnCdS/CdxZn1-xS/ZnS were incorporated into the solution-processed hybrid QD-based light-emitting device structure as the emissive layer. We find that the presence of the CdxZn1-xS shell makes a profound impact on device performances such as the external quantum efficiency and current efficiency. The corresponding light-emitting diodes exhibited a high EQE exceeding 18%, a peak current efficiency of 3.4 cd A(-1) and low efficiency roll-off. Such excellent results of ZnCdS/CdxZn1-xS/ZnS-based QLEDs are likely attributable to the QD's high PL QY and very thin ZnS outermost shell which did not sacrifice the charge injection efficiency in QLEDs.