In-Situ Dual-Site Passivation of All-Inorganic Perovskite Quantum Dots Using Zwitterionic Taurine for Enhanced Defect Resistance

Abstract

Metal halide perovskite quantum dots (PQDs) possess exceptional optical properties but suffer from structural instability under thermal, moisture, and light exposure due to the dynamic bonding of long-chain organic ligands and the ionic nature of their crystal structure. These instabilities increase surface defects and non-radiative recombination, limiting their potential in next-generation optoelectronic devices. In this work, we present a strategy to simultaneously control surface passivation by introducing the zwitterionic ligand taurine during the in-situ synthesis of CsPbBr3 PQDs. The SO3 -group of taurine strongly coordinates with surface Pb 2+ , while the NH3 + group electrostatically interacts with Br -ions, enabling effective dual-site passivation at the PQDs surface. As a result, taurine-based PQDs exhibit enhanced QY compared with PQDs synthesized using conventional long-chain ligands. The PQDs also maintain strong photoluminescence in aqueous environments for 140 h and demonstrate improved thermal stability at 120 °C relative to pristine CsPbBr3 PQDs. Furthermore, dual-site passivation lowers trap density, while the short taurine ligand enhances charge mobility, yielding electronic properties favorable for device applications. This study demonstrates that zwitterionic ligand engineering is an effective strategy to simultaneously improve the stability and performance of perovskite quantum dots, offering a promising pathway for the development of high-performance optoelectronic devices.