Lewis Acid-Driven Perovskite Quantum Dot Surface Reconstruction for Deep-Blue LEDs Approaching the Rec. 2020 Standard.

Perovskite quantum dot light-emitting diodes (PQD LEDs) are promising candidates for high-color-gamut displays, yet deep-blue devices meeting the Rec. 2020 standard with high efficiency and stability remain a tremendous challenge. Here we present a Lewis acid-driven surface reconstruction strategy to enable high-performance deep-blue CsPbBr3 PQD LEDs. Strong ionic interactions between Sr2+ and octanoic acid promote octylamine protonation, triggering simultaneous PQD size reduction, defect suppression, and photoluminescence quantum yield (PLQY) enhancement. The reconstructed PQDs exhibit deep-blue emission at 461 nm with a narrow 18 nm full width at half-maximum and a PLQY of 80%. The resulting LEDs deliver 98.1% color purity, color coordinates of (0.146, 0.059), and full compliance with Rec. 2020 blue specifications. A peak external quantum efficiency of 8.5% and an operational half-lifetime of 41 min are achieved, among the highest reported for pure-bromide deep-blue PQD LEDs. This work provides a facile surface-engineering strategy for efficient deep-blue optoelectronics.