Tetraalkylammonium Halide-Based One-Pot Ligand Engineering of Organic–Inorganic Hybrid Perovskite Nanocrystals for Enhanced Long-Term Stability and Controlled Photoluminescence

Organic–inorganic hybrid perovskite nanocrystals have attracted scientific attention owing to their efficient and controlled photoluminescence, which is highly advantageous for optoelectronic applications. However, the limited long-term stability of organic–inorganic hybrid perovskite nanoparticles (OIHP NPs) has significantly hindered their practical and reliable application. Despite several synthetic strategies and encapsulation methods to stabilize OIHP NPs, complicated multi-step procedures are often required. In this study, we introduce a one-pot ligand engineering method for stabilizing and controlling the optical properties of OIHP NPs using tetraalkylammonium (TAA) halides with various molecular structures at different concentrations. Our one-pot ligand engineering substantially enhanced the stability of the OIHP NPs without post-synthetic processes. Moreover, in certain cases, approximately 90% of the initial photoluminescence intensity was preserved even after a month under ambient conditions. To determine the role of ligand engineering in stabilizing the OIHP NPs, the surface binding properties of the TAA ligands were thoroughly analyzed using Raman spectroscopy. Specifically, the permanent positive charge of the TAA cations and consequent effective electrostatic interactions with the surfaces of the OIHP NPs are pivotal for preserving the initial photoluminescence properties. Our investigation is beneficial for developing OIHP nanocrystals with improved stability and optical tunability for various optoelectronic applications, such as light-emitting devices, photosensitizers, photodetectors, photocatalysis, and solar cells.