Synthetic and Post-Synthetic Strategies to Improve Photoluminescence Quantum Yields in Perovskite Quantum Dots

Chaehyun Lee,Yeji Shin,Iván Mora-Seró,Yeonsu Woo,Sung-Hwan Han,Soo Jeong Lee,Andrés Fabián Gualdrón-Reyes,Seog Joon Yoon

doi:10.3390/catal11080957

Abstract

Making high-quality raw materials is the key to open the versatile potential of next generation materials. All-inorganic CsPbX3 (X: Cl−, Br−, and/or I−) perovskite quantum dots (PQDs) have been applied in various optoelectronic devices, such as photocatalysis, hydrogen evolution, solar cells, and light-emitting diodes, due to their outstanding photophysical properties, such as high photoluminescence quantum yield (PLQY), absorption cross-section, efficient charge separation, and so on. Specifically, for further improvement of the PLQY of the PQDs, it is essential to diminish the non-radiative charge recombination processes. In this work, we approached two ways to control the non-radiative charge recombination processes through synthetic and post-synthetic processes. Firstly, we proposed how refinement of the conventional recrystallization process for PbI2 contributes to higher PLQY of the PQDs. Secondly, after halide exchange from CsPbI3 PQDs to CsPbBr3, through an in situ spectroelectrochemical setup, we monitored the positive correlation between bromide deposition of on the surface of the perovskite and photoluminescence improvement of the CsPbBr3 perovskite film through electrodeposition. These two strategies could provide a way to enhance the photophysical properties of the perovskites for application to various perovskite-based optoelectronic devices.

Highlights

The ABX3 hybrid perovskites (A = MA+, FA+, and Cs+, where MA+ : methylammonium, formamidinium, B = Pb2+ and Sn2+, and X = Cl−, Br−, and I− ) with various dimensions (0D to 3D) have been widely studied for application to various optoelectronic devices, especially for boosting photoconversion efficiency of the perovskite-based solar cell up to25.17% [1,2,3]
We focused on the early stage, how the conventional recrystallization process for perovskite precursors affects the photophysical performance of the perovskite quantum dots (PQDs)
To study the impact of the internal defect in the PQDs to their photophysical properties, we firstly focused on the most frequently used PQD, CsPbI3 PQDs, and even various chemicals which were applied in the hot-injection method to synthesize the CsPbI3 PQDs, we focused on one of the most important precursors, PbI2, which affects 1. stoichiometry and 2. halide-mediated defects in CsPbI3 PQDs

Summary

Introduction

In the perovskite-based research field, using high-purity precursors is widely accepted among researchers for better photophysical properties such as high photoluminescence quantum yield (PLQY) for perovskite quantum dots (PQDs), high absorption cross-section, efficient charge separation, and advanced device performance [4,5,6]. The major reasons of current loss could be as follows: (1) free carrier trapping in the perovskite at various internal/surface. To increase the efficient electron/hole separation and photoinduced current generation, researchers have been focused on decreasing surface defects by increasing grain size [8,13,14], surface defect passivation [15], applying recrystallization process of as-synthesized perovskite to reduce impurity to reduce internal defects [4], and so on. Decreasing halide-induced defects in the perovskite is one of the important strategies for their better photophysical properties and efficient perovskite-based device performance

Methods

Results

Conclusion