Manipulating the Carrier Transfer Dynamics Enabled by Electron Cloud Redistribution for Low-Threshold Red Perovskite...

Red lasers hold significant prospects in biomedicine and industrial processing. Metal-halide perovskites provide promising gain media for red photonic sources owing to their versatile optical properties. However, the perovskite-based coherent emission in the red spectral region still lags far behind due to severe defect-induced nonradiative losses and a labile lattice. Herein, by incorporating phenethylammonium trifluoroacetate (PEATFA) to regulate surface electron cloud redistribution in perovskite CsPbBrI₂ films, we not only enhance lattice rigidity but also provide coordination between C═O groups and undercoordinated Pb²⁺ ions to suppress defects, thereby reconstructing the carrier recombination pathway. The PEATFA-passivated red films exhibit rapid and efficient carrier transfer with an improved gain coefficient and an extended gain lifetime up to 276 ps, enabling a remarkably low amplified spontaneous emission threshold of 1.5 μJ cm^-2. Consequently, benefiting from the significantly promoted radiative recombination and enhanced gain, we construct a vertical cavity to achieve a red single-mode lasing at 660 nm at room temperature, featuring a record-low threshold of 9.42 μJ cm^-2 and a highly linear polarization degree of 87.4%. This study demonstrates a robust route and versatile platform toward miniaturized and integrated red laser sources.