Blue perovskite light-emitting diodes with ultra-low efficiency roll-off through synergistic PVK incorporation and antisolvent treatment

Abstract

Metal halide perovskites have garnered significant attention as next-generation luminescent materials due to their exceptional properties, such as narrowband emission and solution processability. PPA₂(Rb₀.₇₅Cs₀.₂₅)Pb₂Br₇ stands out as a promising wide-bandgap blue perovskite, whereas its deep valence band maximum hinders efficient radiative exciton recombination at the interface with the carrier transport layer. Here, we systematically investigated the effect of the poly-N-vinylcarbazole (PVK) interface and antisolvent treatment on the performance of PPA₂(Rb₀.₇₅Cs₀.₂₅)Pb₂Br₇-based blue devices. Various antisolvent treatments and PVK concentrations were optimized, significantly improving perovskite film quality. Crucially, PVK, serving as both a hole transport and electron-blocking layer, was studied with optimized antisolvent treatment to improve perovskite crystallization and enhance charge transport. Consequently, the blue perovskite light-emitting diode achieved a more than 10-fold improvement in external quantum efficiency, with an exceptionally low efficiency roll-off of only 4 % across a broad current density range from 3.6 to 100 mA cm⁻².