In situ cadmium surface passivation of perovskite nanocrystals for blue LEDs
In situ cadmium surface passivation of perovskite nanocrystals for blue LEDs
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DOI：
10.1039/d1ta08756h
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发表时间：
2021-11-22
影响因子：
11.9
通讯作者：
Lee, Bo Ram
中科院分区：
文献类型：
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作者：
Jeong, Woo Hyeon;Yu, Zhongkai;Lee, Bo Ram
下一代电致发光显示器需要高效稳定的红、绿色和蓝色发光二极管（LED），其具有低成本、优异的色纯度和柔性，其中基于钙钛矿的LED（PeLED）是有希望的候选者。在三基色中，蓝色PeLED的低效率和差的稳定性是其商业化的主要障碍。在这里，我们报告了一种原位表面工程策略，将一个简单的热注入方法与一锅合成的镉离子（Cd 2+）到蓝色发光的全无机钙钛矿纳米晶体（PNC）的表面钝化。优化的PNC含有0.2%的镉显示出改善的光致发光量子产率（PLQY; 66.8%）和环境稳定性相比，净PNC（25.5%）在475 nm的发射波长。具有PNC的PeLED显示出51 cd m（-2）的亮度和3.71%的EQE。通过一系列从头算计算和全面的XPS分析，我们表明镉可能通过钙钛矿B位的表面夹杂物掺入到具有降低维度的系统（例如PNC）中，这有效地抑制了卤化物缺陷的形成并提高了器件效率。
Next-generation electroluminescent displays require efficient and stable red, green and blue light-emitting diodes (LEDs) with low cost, excellent color purity and flexibility, for which perovskite-based LEDs (PeLEDs) are a promising candidate. Among the three primary colors, the low efficiencies and poor stability of blue PeLEDs is the major hurdle to their commercialization. Here, we report an in situ surface engineering strategy incorporating a simple hot injection method with one pot synthesis for surface passivation of cadmium ions (Cd2+) into blue-emissive all-inorganic perovskite nanocrystals (PNCs). The optimized PNCs containing 0.2% Cd show improved photoluminescence quantum yield (PLQY; 66.8%) and ambient stability compared to the neat PNCs (25.5%) at an emission wavelength of 475 nm. PeLEDs with the PNCs show a luminance of 51 cd m(-2) and EQE of 3.71%. Through a series of ab initio calculations and comprehensive XPS analysis, we show that Cd incorporation into systems with reduced dimensionality such as PNCs likely takes place via surface inclusion in the perovskite B-site, which effectively suppresses the formation of halide defects and yields enhanced device efficiencies.