Halide Exchange via Halogenated Hydrocarbons Toward Bright Deep-Blue Perovskite Light-Emitting Diodes

Halide exchange, achieved by post-treating perovskite film with a chloride ion solution, has been demonstrated as an effective strategy for achieving deep-blue perovskites. However, the exchange solution usually utilizes high-polarity solvents, which can potentially damage the perovskite films, resulting in numerous defects. Here, an effective approach to achieving high-quality deep-blue perovskite films through in situ halide exchange using a nondestructive halogenated hydrocarbon solution (BC, benzyl chloride) is presented. It is found that BC, doped with a nucleophile tripropyl phosphine, can release chloride ions through a nucleophilic substitution reaction. Based on this exchange solution, deep-blue perovskite light-emitting diodes (LEDs) with color coordinates of (0.137, 0.045), are achieved fully meeting the Rec. 2020 standard. These devices achieve an external quantum efficiency of ≈5% at a high luminance of 1000 cd cm⁻². Moreover, the devices exhibit a half-lifetime of 42 min at an initial luminance of 100 cd m⁻², representing the most stable deep-blue perovskite LEDs.