Highly efficient CsPbBr3 perovskite nanocrystals induced by structure transformation

A breakthrough on the synthesis and photoelectric device application of highly efficient perovskite quantum dots (PQDs) was made by researchers from Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), making cover story of the July issue of the Journal of Materials Chemistry C, published by Britain’s Royal Society of Chemistry.

 

CIOMP researchers were able to induce obvious fluorescence enhancement when they transformed CsPbBr3 to Cs4PbBr6 perovskite nanocrystals (PNCs). The maximum quantum yields (QY) of the prepared CsPbX3 quantum dots (QDs) can reach up to 99%. The resulting QDs was successfully implemented on the LED application.

 

This work is beneficial to the preparation of QDs and will increase the application of PQDs in optoelectronic devices. Related work was published by Dr. SU Ying and Associate Professor ZENG Qinghui of CIOMP.

 

With the fast development and extensive investigations of halogen atom-based PQDs, the perovskite family of compounds (e.g., Cs4PbBr6 PNCs has gradually drawn researchers’ attention. Recently, research studies have focused on the chemical transformation between 'nonluminous' Cs4PbX6 PNCs and luminescent CsPbX3 QDs. Herein, a new method has been implemented to enable CsPbBr3 (113-structure) QDs gradually to transform into Cs4PbBr6 (416-structure) PNCs by adding ZnBr2 as a revulsive for the detection of the obvious fluorescence enhancement and the deep mechanism behind this transformation.

 

Characterization of morphological, optical, and physicochemical properties reveals that the fluorescence QY of the remaining CsPbBr3 QDs still remain high,  almost up to 99% owing to the reduction of the nonradiative process and the process of 'Survival of the fittest' that occurred in the CsPbBr3 QDs, in which the good quality and stable CsPbBr3 QDs are retained, while the unstable CsPbBr3 QDs with poor quality are decomposed to ripen into the 416-structure.

 

Simultaneously, researchers from CIOMP observed the precise luminous peak position of the ultraviolet fluorophore 416-structure Cs4PbBr6 PNCs and found that the strong green fluorescence comes from CsPbBr3 QDs exclusively. Finally, green light-emitting diodes based on CsPbBr3 QDs with enhanced fluorescence are successfully developed, which implies their tremendous potential in photoelectric devices in the future.

Figure 1 Front cover page(Photo by CIOMP) 

 

                                         

                              

                                            

  

Figure 2 The images of the dried  PQDs with the amount of ZnBr2 revulsive being increased from 10% to 30%, 50%, 70% and 80% under ambient conditions (a) Under 365 nm light irradiation (b) The PL QY of the  PQDs with the amount of ZnBr2 revulsive being increased from 10% to 30%, 50%, 70% and 80% in hexane solution (c) Absorption and emission spectrum of the approximately single phase Cs4PbBr6  PNCs in hexane solution, and the excitation wavelength is 280 nm (d) The fluorescence lifetime decay curves of the CsPbBr3 PQDs in hexane solution with the amount of revulsive being increased from 10% to 30%, 50%, 70% and 80%, and the excitation wavelength is 360 nm (Photo by CIOMP)

 

 

Article links: https://doi.org/10.1039/C9TC01763A

Author: ZENG Qinghui

State Key Laboratory of Luminescence and Applications

E-mail: qhzeng@ciomp.ac.cn

 

 

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