Diffusion dynamics coupled with in situ etching enable controlled growth of InAs quantum dots with narrow SWIR emission

Colloidal InAs quantum dots (CQDs) are promising materials for shortwave infrared (SWIR) optoelectronics because of their heavy-metal-free composition and tunable long-wavelength emission. However, achieving high-quality InAs CQDs with narrow linewidths and symmetric emission beyond 1500 nm remains challenging, primarily due to uncontrolled growth kinetics and surface defects during high-temperature synthesis. Here, we report a unified strategy that overcomes this synthesis–emission trade-off by integrating in situ HBr-assisted dual-site etching with a diffusion-dynamics-controlled continuous injection process. This approach stabilizes the nanoclusters and seeds simultaneously, suppresses secondary nucleation, and enables kinetically synchronized growth. Complementary density functional theory (DFT) calculations offer a mechanistic insight into the surface-driven growth modulation and confirm that Br– treatment enhances facet-specific binding and suppresses mid-gap states. The resulting InAs CQDs exhibit symmetric single-peak emission centered at ∼1510 nm with an average diameter of ∼7.2 nm, narrow size distribution (coefficient of variation (CV) = 11.5%), excitonic linewidths (half-width at half maximum (HWHM) < 70 meV), and long-term colloidal stability. These results redefine the synthetic framework for III–V CQDs and provide a scalable route for high-performance heavy-metal-free SWIR emitters.