Tunable bandgap PbS colloidal quantum dots for infrared detectors with absorption peak up to 2 μm

Colloidal quantum dots (CQDs), with their excellent spectral tunability and solution-processability, show great potential in next-generation infrared optoelectronics. This study focuses on an improved stepwise hot-injection method for the precise synthesis of large-sized PbS CQDs. By precisely controlling the nucleation-growth dynamics, we successfully synthesize PbS quantum dots with excellent monodispersity, diameters exceeding 10.6 nm, a narrow size distribution (relative standard deviation of approximately 6%), and a distinct excitonic absorption peak at 2.08 μm. The synthesized quantum dots are integrated into photodetectors, achieving a high specific detectivity of 1.56 × 10 11 Jones at 1.6 μm wavelength. This provides a viable pathway for the fabrication of high-performance, solution-processable quantum dot infrared detectors.