Surface pre-optimization of a mixed halide perovskite toward high photoluminescence quantum yield in the blue spectrum range

• Published in: Nanoscale Vol. 11; no. 32; pp. 1526 - 15215
• Main Authors: Luo, Chao, Li, Wen, Xiong, Da, Fu, Ji, Yang, Weiqing
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 15.08.2019
• Subjects: Diodes; Optimization; Organic light emitting diodes; Perovskites; Photoluminescence; Praseodymium; Quantum dots; Radiative recombination; White light
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c9nr05217h

The photoluminescence quantum yields (PLQYs) of all-inorganic halide perovskites in the green and red spectral ranges have approached over 90%, overwhelmingly arousing burgeoning interests for creating a revolution in next-generation high-definition displays. However, obtaining pure blue-emitting perovskites with high PLQYs still remains a challenge. Herein, we designed a novel strategy to pre-optimize CsPbCl 3 quantum dots (QDs) using praseodymium( iii ) chloride (PrCl 3 ), and then efficient blue-emitting CsPbBr x Cl 3− x QDs were obtained through halide exchange between the optimized CsPbCl 3 and efficient CsPbBr 3 QDs. Specifically, the PrCl 3 optimization simultaneously and efficiently passivated the surface vacancy defects and appropriately reduced the surface long-chain organic ligands of the CsPbCl 3 QDs, synergistically eliminating the deep trap states, and hence considerably suppressing nonradiative recombination. As a result, the radiative recombination rate was enhanced by more than one order of magnitude from 4.3 to 79 μs −1 . Benefiting from this, the blue-emitting CsPbBr x Cl 3− x QDs exhibited an admirable PLQY of up to 89%, which is competitive compared with that of the state-of-the-art red and green-emitting perovskites. This strategy provides a unique understanding regarding the low PLQY of blue-emitting perovskites and an efficient method to boost it, which is especially attractive for constructing efficient blue and white light-emitting diodes. The photoluminescence quantum yields (PLQYs) of all-inorganic halide perovskites in the green and red spectral ranges have approached over 90%, overwhelmingly arousing burgeoning interests for next-generation high-definition displays.