Single-Source Thermal Evaporation Growth and the Tuning Surface Passivation Layer Thickness Effect in Enhanced Amplified Spontaneous Emission Properties of CsPb(Br0.5Cl0.5)3 Perovskite Films.

Saif M H Qaid,Hamid M Ghaithan,Abdullah S Aldwayyan,Bandar Ali Al-Asbahi

doi:10.3390/polym12122953

Saif M H Qaid, Hamid M Ghaithan + Show 2 more

Open Access

https://doi.org/10.3390/polym12122953

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Journal: Polymers	Publication Date: Dec 10, 2020
Citations: 15	License type: CC BY 4.0

Affiliation: King Saud University, Ibb University, Sana'a University

Abstract

High-quality inorganic cesium lead halide perovskite CsPb(Br0.5Cl0.5)3 thin films were successfully achieved through evaporation of the precursors and deposition sequentially by a single-source thermal evaporation system. The different melting points of the precursors were enabled us to evaporate precursors one by one in one trip. The resulting films through its fabrication were smooth and pinhole-free. Furthermore, this technique enabled complete surface coverage by high-quality perovskite crystallization and more moisture stability oppositely of that produce by solution-processed. Then the perovskite films were encapsulated by evaporated a polymethyl methacrylate (PMMA) polymer as a specialized surface passivation approach with various thicknesses. The blue emission, high photoluminescence quantum yield (PLQY), stable, and low threshold of amplified spontaneous emission (ASE) properties of CsPb(Br0.5Cl0.5)3 films in the bulk structure at room temperature were achieved. The effects of the surface-passivation layer and its thickness on the optical response were examined. Detailed analysis of the dependence of ASE properties on the surface passivation layer thickness was performed, and it was determined this achieves performance optimization. The ASE characteristics of bare perovskite thin film were influenced by the incorporation of the PMMA with various thicknesses. The improvement to the surface layer of perovskite thin films compared to that of the bare perovskite thin film was attributed to the combination of thermal evaporation deposition and surface encapsulation. The best results were achieved when using a low PMMA thickness up to 100 nm and reducing the ASE threshold by ~11 μJ/cm2 when compared with free-encapsulation and by ~13 μJ/cm2 when encapsulation occurs at 200 nm or thicker. Compared to the bare CsPb(Br0.5Cl0.5)3, ASE reduced 1.1 times when the PMMA thickness was 100 nm.

Highlights

Organic-inorganic and inorganic lead halide perovskite structures with monovalent A cations and X anions have prominent APbX3 (e.g., A = Cs, MA, and FA; Polymers 2020, 12, 2953; doi:10.3390/polym12122953 www.mdpi.com/journal/polymersX = Cl, Br, and I, respectively)
Encapsulation of the top layer of perovskite films was achieved in a single-source thermal evaporation system by using polymethyl methacrylate (PMMA) as a specialized surface passivation approach
The achieved amplified spontaneous emission (ASE) from the bulk structures of CsPb(Br0.5 Cl0.5 )3 confirms that efficient light emission can be achieved from sources other than CsPbX3 perovskites nanoparticles

Summary

Introduction

The low formation energy of crystal lattices coupled with the high delocalization activity of surface ions makes CsPbX3 highly susceptible to polar solvents and sensitive to moisture and air, anion-exchange reactions, and thermal heating in practical operation [7,8,9,10]. Such inherent instability significantly impedes the further development and future application of CsPbX3 in optoelectronics fields. PMMA polymers have been widely used as the material of choice in plastic optical fiber fabrication [30,32] and optoelectronic applications [33]

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