Ligand-mediated CsPbBr x I 3- x /SiO 2 quantum dots for red, stable and low-threshold amplify spontaneous emission.

The red-emitting perovskite material has received widespread attention as a long-wavelength optical gain media. But the easy phase change in the air limits its practical application. Herein, red CsPbBr x I 3- x /SiO 2 quantum dots (QDs) are prepared by a ligand-mediated hot injection method in which 3-aminopropyl-triethoxysilane (APTES) is used instead of the usual oleylamine (OAm) ligand. Through the hydrolysis of amino groups, a thin silicon layer is formed on the QD surface, improving the stability and without causing the aggregation of QDs. We find that the ratio of I/Br and the size of QDs can be tuned by adjusting the APTES amount. Moreover, this ligand-mediated synthesis effectively passivates the surface defects, so the photoluminescence quantum yield is remarkably improved, and the carrier lifetime is prolonged. The amplified spontaneous emission is achieved under 532 nm nanosecond laser excitation. Compared with the original CsPbBrI 2 -OAm QD films, the threshold of CsPbBr x I 3- x /SiO 2 QD films is reduced from 403.5 to 98.7 μ J cm -2 , and the radiation stability is significantly enhanced. Therefore, this material shows great potential in the random laser field.