High‐Efficiency Formamidinium Lead Bromide Perovskite Nanocrystal‐Based Light‐Emitting Diodes Fabricated via a Surface Defect Self‐Passivation Strategy,Advanced Optical Materials

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High‐Efficiency Formamidinium Lead Bromide Perovskite Nanocrystal‐Based Light‐Emitting Diodes Fabricated via a Surface Defect Self‐Passivation Strategy
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2020-01-15 , DOI: 10.1002/adom.201901390
Hongting Chen ₁ , Lianwei Fan ₁ , Rui Zhang ₁ , Chunxiong Bao ₂ , Haifeng Zhao ₂ , Wei Xiang ₁ , Wei Liu ₁ , Guangda Niu ₁ , Runda Guo ₁ , Louwen Zhang ₁ , Lei Wang ₁

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Formamidinium lead bromide (FAPbBr₃) nanocrystals (NCs) demonstrate great potential in light‐emitting diode (LED) applications due to their pure green emission and excellent stability. However, the abundant defects at the surface of the NCs act as charge trapping centers and significantly increase the trap‐assisted nonradiative recombination channels, hampering the performance improvement of LEDs based on FAPbBr₃ NCs. Herein, a facile self‐passivation strategy of the surface defects is developed by introducing excess formamidinium bromide (FABr) during the colloidal synthesis of NCs, leading to much improved photoluminescence quantum yield (PLQY) of the obtained NCs. In addition, enhanced charge transport property is measured in the assembled films owing to the simultaneously declined insulating ligands at the surface of NCs. The molar ratio of FABr and PbBr₂ is rationally optimized during the synthesis of NCs and high‐efficient green‐emissive LEDs are fabricated with a champion current efficiency of 76.8 cd A⁻¹, corresponding to an external quantum efficiency of 17.1%, which is among the best‐performing green LEDs based on perovskite NCs so far.

中文翻译：

通过表面缺陷自钝化策略制备的高效甲Form鎓溴化钙钛矿纳米晶体基发光二极管

甲酰溴化铅（FAPbBr ₃）纳米晶体（NCs）具有纯绿色发射和出色的稳定性，因此在发光二极管（LED）应用中显示出巨大潜力。但是，NC表面的大量缺陷充当电荷俘获中心，并显着增加了陷阱辅助的非辐射复合通道，从而阻碍了基于FAPbBr ₃的LED的性能改进。NCs。在此，通过在NC的胶体合成过程中引入过量的甲form溴化物（FABr），开发了一种表面缺陷的简便自钝化策略，从而大大提高了所获得NC的光致发光量子产率（PLQY）。另外，由于在NC表面上同时下降的绝缘配体，在组装的膜中测量到增强的电荷传输性质。在NC合成过程中合理地优化了FABr和PbBr ₂的摩尔比，并以76.8 cd A ^-1的峰值电流效率制造了高效绿色发射LED ，相当于外部量子效率为17.1％，这是是迄今为止基于钙钛矿NC的性能最好的绿色LED之一。

更新日期：2020-03-20

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