Brightening deep-blue perovskite light-emitting diodes: a path to Rec. 2020

High-purity deep-blue perovskite light-emitting diodes (PeLEDs) are essential for next-generation displays that meet the Rec. 2020 standard. However, halide vacancies, particularly chloride, cause bandgap instability and reduced LED performance in mixed-halide perovskites. We present a chloride vacancy passivation (CVTP) strategy using sulfonate group ligands with varying chain lengths, which strongly bind to Pb(II) ions and fill the vacancies. This approach prevents phase segregation, producing color-stable deep-blue PeLEDs with a 461 nm emission peak and 2,707 cd/m2 luminance, among the highest for Rec. 2020 compliant PeLEDs. Additionally, external quantum efficiency improved to 5.68%, influenced by ligand chain length.