Atomic Characterization of Byproduct Nanoparticles on Cesium Lead Halide Nanocrystals Using High-Resolution Scanning Transmission Electron Microscopy

Mian Zhang,Hongbo Li,Zhenda Lu,Qiang Jing,Peng Wang

doi:10.3390/cryst8010002

Mian Zhang, Hongbo Li + Show 3 more

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https://doi.org/10.3390/cryst8010002

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Abstract

Recent microstructural studies on lead halide perovskite nanocrystals have consistently reported the coexistence of byproduct nanoparticles (NPs). However, the nature of these NPs and their formation mechanism are still a matter of debate. Herein, we have investigated the structure and compositions of the NPs located on colloidal cesium lead bromide nanocrystals (CsPbBr3 NCs), mainly through aberration-corrected transmission electron microscopy and spectroscopy. Our results show that these NPs can be assigned to PbBr2 and CsPb2Br5. The new CsPb2Br5 species are formed by reacting CsPbBr3 NCs with the remaining PbBr2 during the drying process. In addition, observation of the metallic Pb NPs are ascribed to the electron damage effect on CsPbBr3 NCs during transmission electron microscopy imaging.

Highlights

Lead halide perovskite (LHP) materials have attracted significant attention in recent years, due to their promising applications in solar cells [1,2,3,4,5], light emitting diodes (LEDs) [6,7,8,9], lasers [10,11,12,13], and photo-detectors [14,15,16,17]
The transmission electron microscopy (TEM) experiments presented here demonstrate that the byproduct NPs on CsPbBr3 NCs is a mix of PbBr2 and CsPb2 Br5
We propose here that the excess reactant of PbBr2 during the synthesis and, subsequently, the incomplete purification of the CsPbBr3 products, synergetically led to the final excess precipitation of the PbBr2 NPs on CsPbBr3 NCs after solvent evaporation

Summary

Introduction

Lead halide perovskite (LHP) materials have attracted significant attention in recent years, due to their promising applications in solar cells [1,2,3,4,5], light emitting diodes (LEDs) [6,7,8,9], lasers [10,11,12,13], and photo-detectors [14,15,16,17]. In the family of LHP materials, colloidal all-inorganic cesium lead halide (CsPbX3 , X = Cl, Br, and I) perovskite nanocrystals combine both high stability and superior high luminescent efficiency compared to their organic-inorganic counterparts [18,19]. With their colloidal properties, many works have concentrated on applying them to solution-processed devices such as display screens [20], lasers [12] and LEDs [8]. One report suggests that these NPs are PbBr2 [21] and another report claims that these NPs are CsPb2 Br5 [22]

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