Low‐threshold Amplified Spontaneous Emission of Dion‐Jacobson Phase Perovskite Films Achieved by Tuning Diamine Cation Size

Dion‐Jacobson (DJ) phase perovskites have received attention in the field of amplified spontaneous radiation (ASE) and lasers due to their excellent structural stability and charge transfer performance. However, the effect of the diamine cation size on the ASE properties of DJ phase perovskite has not been studied. Herein, we systematically study the effect and the results show that tuning the size of the diamine cation can inhibit the formation of the small‐n phases, reduce the surface roughness, and passivate defects of DJ phase perovskite films. Based on those, we realize the low‐threshold ASE (65 μJ cm−2 under nanosecond laser excitation) of the 1,3‐propylenediamine cation (PDA)‐based DJ phase perovskite films. Additionally, the film exhibits excellent photostability. The ASE intensity remains at 90% of the original value after a pulsed laser irradiation of 3000 μJ cm−2 for 120 min. This work provides a strategy to realize high‐performance DJ phase perovskite ASE and lasers.This article is protected by copyright. All rights reserved.