ABSTRACT Deep‐blue perovskite light‐emitting diodes (PeLEDs) are essential for the full‐color commercialization of PeLED‐based displays. Although recent studies report external quantum efficiencies exceeding 10%, their application remains limited by low luminance (typically around 100 cd m − 2 ) and spectral instability during operation. Here, a dual‐passivating additive‐based synergetic solid‐state halide exchange (DASH) process is introduced to address these challenges and realize highly bright and spectrally stable deep‐blue PeLEDs. The DASH process employs chlorodiphenylphosphine, a chlorine‐containing additive devoid of long alkyl chains that will otherwise hinder conductivity. This additive offers dual passivation via its lone‐pair electrons and chloride ions, while simultaneously enabling nondestructive chloride incorporation into pristine perovskite films, yielding improved morphology, enhanced photoluminescence quantum yield, and homogeneous halide composition. The emission spectrum is tunable from green (512 nm) to deep‐blue (434 nm), representing the largest color shift reported to date. The optimized PeLEDs exhibit peak emission at 459 nm with Commission Internationale de l'Éclairage coordinates of (0.141, 0.041), achieving a maximum luminance of 237.7 cd m − 2 . This work establishes a passivation‐coupled halide‐exchange strategy that enables blue perovskite emitters to achieve both spectral stability and high luminance.
Lee et al. (Mon,) studied this question.