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arXiv · 1910.09105

Electrochemically-stable ligands bridge photoluminescence-electroluminescence gap of quantum dots

Chaodan Pu·Xingliang Dai·Yufei Shu·Meiyi Zhu·Yunzhou Deng·Yizheng Jin·Xiaogang Peng
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Abstract

Colloidal quantum dots (QDs) are promising emitters for electroluminescence devices (QD light-emitting-diodes, QLEDs). Though QDs have been synthesized with efficient and stable photoluminescence, inheriting their superior luminescence in QLEDs remains challenging. This is commonly attributed to unbalanced charge injection and/or interfacial exciton quenching in the devices, instead of lack of suited QD materials. Here, a general but previously overlooked degradation channel in QLEDs, i.e., operando electrochemical reactions of surface ligands with injected charge carriers, is identified after systematic studies of various combination of core/shell QDs and ligands. Applying electrochemically-inert ligands to highly photoluminescent QDs is developed to bridge their photoluminescence-electroluminescence gap. This material-design principle is general for boosting electroluminescence efficiency and lifetime of the QLEDs, resulting in record-long operational lifetimes for both red-emitting QLEDs (T95 > 3800 hours at 1000 cd m-2) and blue-emitting QLEDs (T50 >10,000 hours at 100 cd m-2). Our study provides a critical guideline for the QDs to be used in optoelectronic and electronic devices.

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Chaodan Pu, Xingliang Dai, Yufei Shu, Meiyi Zhu, Yunzhou Deng, Yizheng Jin, Xiaogang Peng. 2019-10-21. Electrochemically-stable ligands bridge photoluminescence-electroluminescence gap of quantum dots. https://doi.org/10.1038/s41467-020-14756-5

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