Colloidal quantum dot (QD) solids are emerging semiconductors that have been actively explored in fundamental studies of charge transport¹ and for applications in optoelectronics². 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 transport³. However, in perovskite QDs, the polar solvents used to carry out the ligand exchange decompose the highly ionic perovskites⁴. 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 cm² 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 CsPbBr₃ 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%.

胶体量子点（QD）固体是新兴的半导体，已经在电荷传输的基础研究¹和光电子^2的应用中进行了积极探索。形成高质量QD固体（设备制造所必需的），需要用短的配体替代用于合成的长有机配体，以提供增强的QD偶联和改善的电荷传输³。但是，在钙钛矿量子点中，用于进行配体交换的极性溶剂会分解高离子钙钛矿^4。。在这里，我们报道了钙钛矿的QD重铺表面处理，以实现由内部阴离子壳和由阳离子和极性溶剂分子组成的外部壳组成的双极壳。外壳静电吸附到带负电的内壳上。与先前报道的低维钙钛矿相比，此方法可生产出具有严格限制的钙钛矿QD固体，该固体具有改善的载流子迁移率（≥0.01cm ²  V ^-1  s ^-1）和降低的陷阱密度。发射蓝光的QD薄膜的光致发光量子产率超过90％。通过利用提高的移动性，我们已经能够制造CsPbBr ₃基于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部量子效率为12.3％；绿色器件可实现22％的外部量子效率。