Retarding Energy Transfer Kinetics to Suppress Auger Recombination for Low-Threshold Amplified Spontaneous Emission in Perovskite Heterostructures

Quasi-2D perovskites offer efficient energy funneling for lasing applications, yet ultrafast carrier injection into the gain centers triggers severe Auger recombination, while poor environmental stability further hinders their practical use. Here, we construct a 0D/quasi-2D multiphase heterostructure via mFPEA+ and TmPA+ incorporation, wherein the 0D Cs4PbBr6 phase acts as an energy reservoir and physical barrier. Transient absorption spectroscopy reveals that the stepwise cascade retards energy-transfer time from 9.38 to 19.03 ps, suppresses Auger recombination (Auger lifetime prolonged from 76.29 to 130.52 ps), and extends the carrier lifetime in the gain phase from 192.4 to 351.6 ps. Meanwhile, the 0D phase passivates uncoordinated defects and blocks moisture/oxygen. Consequently, the amplified spontaneous emission (ASE) threshold is reduced from 120.1 μJ cm–2 for the control film to 13.5 μJ cm–2, with excellent ASE stability under continuous pumping and 15-day ambient-air exposure. This work establishes kinetic modulation of energy transfer as a powerful strategy for suppressing Auger recombination in perovskite laser.