Hydrogen bond engineering for defect passivation and performance enhancement in the one-dimensional copper-based...

The mechanochemical ball-milling process for one-dimensional copper-based perovskite-like halide Cs₅Cu₃Cl₆I₂ is recognized as a crucial pathway for scalable and sustainable production. However, crystal lattice defects are often introduced during synthesis, which promote non-radiative recombination and lead to performance degradation. Herein, a hydrogen-bond engineering strategy through NH₄⁺ lattice doping was implemented to enhance the optoelectronic performance and stability of Cs₅Cu₃Cl₆I₂. Notably, the NH⋯Cl hydrogen bonds were successfully visualized for the first time in copper-based perovskite-like halides through independent gradient model and electron localization function analyses. Furthermore, the passivation model built upon density functional theory calculations and device simulations, confirmed the effective passivation of Cl vacancies and I-Cl anti-site defects by these hydrogen bonds, along with suppressed halide ion migration, resulting in a significant suppression of non-radiative recombination. Consequently, the photoluminescence quantum yield was boosted from 46.27% to 72.40%, along with a 21.42% prolongation of fluorescence lifetime and remarkable enhancement in blue UV-pumped phosphor-converted light-emitting diode luminous efficiency. This mechanistic framework is expected to provide valuable guidance for the development of high-performance copper-based perovskites.