Acta Chimica Sinica ›› 2021, Vol. 79 ›› Issue (1): 126-132.DOI: 10.6023/A20080386 Previous Articles    



李严a, 李金航a, 许蕾梦b, 陈嘉伟a, 宋继中a,*()   

  1. a 南京理工大学材料科学与工程学院 新型显示材料与器件工信部重点实验室 南京 210094
    b 郑州大学物理工程学院 材料物理教育部重点实验室 郑州 450001
  • 投稿日期:2020-08-21 发布日期:2020-10-17
  • 通讯作者: 宋继中
  • 作者简介:
  • 基金资助:
    国家自然科学基金(51922049); 国家重大研发计划(2016YFB0401701); 江苏省科技厅(BK20180020); 中央高校基本科研基金(30920032102); 江苏高校优势学科建设工程项目

CsPbI3 Perovskite Quantum Dots: Fine Purification and Highly Efficient Light-emitting Diodes

Yan Lia, Jinhang Lia, Leimeng Xub, Jiawei Chena, Jizhong Songa,*()   

  1. a School of Materials Science and Engineering, MIIT Key Laboratory of Advanced Display Materials and Devices, Nanjing University of Science and Technology, Nanjing 210094, China
    b School of Physics and Engineering, Ministry of Education Key Laboratory of Materials Physcis, Zhengzhou University, Zhengzhou 450001, China
  • Received:2020-08-21 Published:2020-10-17
  • Contact: Jizhong Song
  • Supported by:
    the National Natural Science Foundation of China(51922049); the National Key Research and Development Program of China(2016YFB0401701); the Natural Science Foundation of Jiangsu Province(BK20180020); the Fundamental Research Funds for the Central Universities(30920032102); the Priority Academic Program Development of Jiangsu Higher Education Institutions

Perovskite quantum dot light-emitting diodes (QLEDs) possess the characteristics of high color purity, precise color control, wide gamut, and solution processibility, which shows great prospects in displays and lightings. However, red CsPbI3 quantum dots (QDs) are prone to luminescence degradation due to the thermal non-equilibrium-induced phase transition and ligand loss during the purification process. The purification of CsPbI3 QDs is more difficult than that of CsPbBr3 QDs. Because the ligands on the surface of the quantum dots will be lost continuously during the purification process, resulting in aggregation and transformation toδ-CsPbI3 phase. Aiming at this problem, We prepared the CsPbI3 QDs through a hot-injection method at 180 ℃. The original solution of the perovskite QD also contains impurities such as octadecene solvent, oleic amine, and oleic acid ligand, which will seriously affect the photoelectric properties and destroy the film. So we used different flocculation solvents and dispersion solvents to collaboratively purify the QDs. At last, our work developed a mixed-solvent purification strategy with toluene and ethyl acetate, which can avoid the phase transition during the purification process and lead to pure cubic CsPbI3 QDs. But when we do not add the additional ligands in purification process, the photoluminescence quantum yield (PLQY) of QDs will be far less than 100%. In order to enhance the PLQY, a ligand compensation strategy of using oleylammonium iodide (OAmI) to control the surface state of QDs was proposed, which reduced the surface defects and solved the problem of luminescence quenching caused by ligand loss. We found that 400 μL OAmI enabled quantum dots to have both high PLQY of 70% and excellent electrical properties. Under electrically driven, the exciton recombination probability was significantly increased, and the CsPbI3- based QLED achieved a maximum luminance of 3090 cd/m2 and a maximum external quantum efficiency (EQE) of 15.67%. The proposed fine purification strategy of CsPbI3 QDs has an important guiding significance for the development of high-efficiency QD materials and high-performance optoelectronic devices.

Key words: inorganic perovskite quantum dot, purification, ligand compensation, quantum dot light-emitting diodes (QLEDs), CsPbI3