Bipolar-shell resurfacing for blue LEDs based on strongly confined perovskite quantum dots
Bipolar-shell resurfacing for blue LEDs based on strongly confined perovskite quantum dots
复制标题
基于强约束钙钛矿量子点的蓝色 LED 双极壳表面重修
DOI：
10.1038/s41565-020-0714-5
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发表时间：
2020-07-06
影响因子：
38.3
通讯作者：
Sargent, Edward H.
中科院分区：
文献类型：
--
作者：
Dong, Yitong;Wang, Ya-Kun;Sargent, Edward H.
基于溶液的配体交换策略可以实现具有接近1的光致发光量子产率和高载流子迁移率的紧密堆积的量子点固体薄膜。胶体量子点（QD）固体是新兴的半导体，在电荷传输的基础研究（1）和光电子学的应用（2）中已经被积极探索。形成高质量的量子点固体-器件制造所必需的-需要用短配体取代用于合成的长有机配体，以提供增加的量子点耦合和改善的电荷传输（3）。然而，在钙钛矿QD中，用于进行配体交换的极性溶剂分解高离子钙钛矿（4）。在这里，我们报告了钙钛矿QD表面置换，以实现由内阴离子壳和由阳离子和极性溶剂分子组成的外壳组成的双极壳。外壳被静电吸附到带负电荷的内壳。这种方法产生强约束的钙钛矿QD固体，其特征在于相对于先前报道的低维钙钛矿改善的载流子迁移率（>= 0.01 cm（2）V-1 s（-1））和降低的陷阱密度。蓝光量子点薄膜的光致发光量子产率超过90%。通过利用改进的迁移率，我们已经能够制造基于CsPbBr（3）QD的高效蓝色和绿色发光二极管。陷阱密度降低的蓝色器件的外量子效率为12.3%;绿色器件的外量子效率为22%。
A solution-based ligand-exchange strategy enables the realization of close-packed quantum dot solid films with near-unity photoluminescence quantum yield and high charge carrier mobility.Colloidal quantum dot (QD) solids are emerging semiconductors that have been actively explored in fundamental studies of charge transport(1)and for applications in optoelectronics(2). Forming high-quality QD solids-necessary for device fabrication-requires substitution of the long organic ligands used for synthesis with short ligands that provide increased QD coupling and improved charge transport(3). However, in perovskite QDs, the polar solvents used to carry out the ligand exchange decompose the highly ionic perovskites(4). Here we report perovskite QD resurfacing to achieve a bipolar shell consisting of an inner anion shell, and an outer shell comprised of cations and polar solvent molecules. The outer shell is electrostatically adsorbed to the negatively charged inner shell. This approach produces strongly confined perovskite QD solids that feature improved carrier mobility (>= 0.01 cm(2) V-1 s(-1)) and reduced trap density relative to previously reported low-dimensional perovskites. Blue-emitting QD films exhibit photoluminescence quantum yields exceeding 90%. By exploiting the improved mobility, we have been able to fabricate CsPbBr(3)QD-based efficient blue and green light-emitting diodes. Blue devices with reduced trap density have an external quantum efficiency of 12.3%; the green devices achieve an external quantum efficiency of 22%.