Organic-inorganic hybrid perovskite nanocrystals (PNCs) have attracted scientific interests based on their cost-effectiveness, solution processability, emission tunability, and superior photoluminescence properties such as high photoluminescence quantum yields and narrow full-width half maximum. Despite these advantages, their limited stability under ambient conditions has usually been a major discouraging issue for their practical and reliable applications. Even though advanced ligand chemistry can be taken advantage of for the enhancement of the stability, the selection of ligands should be carefully considered because they might hinder the electronic carrier transport or worsen the photoluminescence properties. In this work, we demonstrate the improvement of stability and photoluminescence of PNCs using tetraalkylammonium halides with various lengths and numbers of alkyl chains. Interestingly, the functionalization of the PNCs using tetraalkylammonium halides highly improves their stability. In addition, the photoluminescence properties of PNCs are controlled using tetraalkylammonium halides, blue-shifting the maximum emission wavelength in a wide range (~60 nm) and increasing the emission intensity as a function of the ligand concentration. We analyze the structures of the tetraalkylammonium-stabilized PNCs using X-ray diffraction (XRD) and Raman spectroscopy to demonstrate the structural variation depending on the types of ligands. Moreover, the photoluminescence properties of PNCs are thoroughly investigated using time-resolved photoluminescence and quantum yield analysis, demonstrating highly stabilized emission of PNCs even after several weeks. Our comprehensive investigation of the enhanced stability and controlled photoluminescence of PNCs using tetraalkylammonium halide ligands would be highly valuable for their optoelectrical applications in practice.

Tetraalkylammonium halide-functionalized perovskite nanocrystals for highly enhanced long-term stability and controlled photoluminescence

ACS Spring 2022

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