Partially Ionized Amino Acid Salt Enabling Spatially Vertical n-Phase Distribution of Quasi-2D Perovskite for Efficient Deep-Blue Light-Emitting Diodes

The deep-blue perovskite light-emitting diodes (PeLEDs) are of essential and indispensable for the application in full-gamut display. However, the deep blue emission required large bandgap in small n phase exhibits high surface activity that gives rise to the difficulty of n phase distribution control spatially and proportionally in quasi-2D perovskite films. Here, the deep-blue pure-bromide perovskite films is present that exhibit spatially vertical n phase distribution, owing to the partially ionized amino acid salt of 3-Ammonium propionic acid bromide (3CBr) modulated crystallization kinetic of perovskite. The strong interaction of 3CBr and perovskite lattice improves the stability of small n phases, showing tunable photoluminescence (PL) emission and enhanced PL quantum yield (PLQY). The achieved champion deep blue PeLED shows a maximum EQE of 3.64% at electroluminescence (EL) emission wavelength of 466 nm, locating at the top rank of the similar devices. This work provides an effective strategy to fabricating efficient deep-blue perovskite films and devices, promoting the development of perovskite-based application in display.