P‐12.3: Management of Domain Distribution by Employing Dual Spacers for Efficient Blue Quasi‐2D Perovskite Light‐Emitting Diodes

Quasi‐2D perovskites featuring with natural multiple quantum‐well structure are promising for achieving highly efficient blue light‐emitting diodes. The undesired domain distribution of quasi‐2D perovskites usually results in inefficient energy cascade and thereby inferior device performance. Here, we regular the domain distribution by incorporating propylamine hydrobromide (PABr) and n‐butylamine hydrobromide (BABr) into pristine perovskites to serve as dual spacers with phenylethylamine hydrobromide (PEABr), respectively. The modified perovskite films show narrower domain distribution and improved optical properties. We further fabricate the perovskite light‐emitting diodes (PeLEDs) based on the modified films. The best devices achieve a maximum external quantum efficiency (EQE) of 2.6%, which is 2.3‐fold to that of control devices. These results may provide a practical method to prepare highly efficient blue PeLEDs.