LAUSR

Here, we discuss a simple low temperature process for the synthesis of small and stable PbS/CdS QDs with emission below 1100 nm. For this, small PbS QDs with emission below 1100 nm synthesized from PbCl2 in oleylamine with 1-dodecanethiol, as reported by our group recently, were used. A thin CdS shell was grown on PbS at room temperature (RT) via cation exchange (CE), which is a self-limiting process providing about 100 nm blue shift in the emission maxima, hence is quite practical for reaction control and production of predictable particles. RTCE process provides 6–9 times stronger emission than original PbS with better optical stability. Annealing of the PbS/CdS QDs in solid state at mild temperatures (50–100 °C) improves crystallinity of the particles. Final ligand exchange on the annealed PbS/CdS with 1-dodecanethiol (DT) enhances the long-term stability of particles further. The optimum overall process is determined as RTCE followed by annealing at 50 °C for 1 h and finished with ligand exchange with...