Balancing monomer and ionic ligand supply for scalable direct synthesis of short-wavelength infrared PbS quantum dot inks

The direct synthesis of semi-conductive quantum dot (QD) inks coordinated by inorganic ions in polar phases presents potential advantages such as low cost and scalability, making it an ideal approach for realizing QDs-based optoelectronic applications. However, the weak repulsive forces between QDs coordinated by inorganic ions can easily lead to agglomeration, significantly limiting size control during the synthesis process. Distinct from the traditional high-temperature injection and low-temperature growth strategy used in the synthesis of QDs with long-chain organic ligands, we discover that low-temperature injection nucleation and high-temperature growth is an effective strategy to achieve controllable tuning of reactive monomers and ligand ions in the direct synthesis system of inorganic ion-liganded QD inks, which in turn realizes the scalable, low-cost, and direct synthesis of uniform and size-tunable short-wavelength infrared (SWIR) PbS QD inks. The yield of single synthesis can be more than 10 g. Compared with the traditional ligand exchange method, the yield is improved by nearly 3 times and the cost is reduced to 7 times. Finally, the solar cell devices fabricated using these PbS SWIR QD inks achieved a photovoltaic conversion efficiency of approaching 9%, confirming the excellent optoelectronic performance of the synthesized PbS QD materials.