Stepwise Crystallization Synthetic Strategy for Monodisperse InSb Colloidal Quantum Dots with Mid‐Infrared Absorption

Colloidal InSb quantum dots (QDs) are promising mid‐infrared (MIR) photodetection materials due to their suitable bandgap, unparalleled room temperature electronic properties, environmental‐friendly elemental composition and facile solution processability. However, current InSb QDs suffer from limited spectral absorption within 2 μm, polydisperse QDs populations and complex size‐selective precipitation for further use, due to the lack of applicable growth theory and synthetic method. Here, we present a novel synthetic strategy for InSb QDs, which is featured by the initial formation of an amorphous intermediate and a subsequent stepwise crystallization process. This strategy enables the achievement of monodisperse InSb QDs with unprecedented 5.8 nm to 22.2 nm size range, and a remarkably low size distribution deviation of 5.8% without the need of any size‐selective precipitation. For the first time, we realize the synthesis of InSb QDs with absorption wavelength exceeding 3000 nm, the record among the environmental‐friendly QDs. The results presented here will pave the way towards environmental‐friendly QDs as outstanding infrared optical and optoelectronic materials and push the frontier of solution‐processed QDs into the mid‐infrared regime applications.