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.

Conjugated polymers have been explored as promising hole-transporting layer (HTL) in lead sulfide (PbS) quantum dot (QD) solar cells. The fine regulation of the inorganic/organic interface is pivotal to realize high device performance. In this work, we propose using CsPbI₃ QDs as the interfacial layer between PbS QD active layer and organic polymer HTL. The relative soft perovskite can mediate the interface and form favorable energy level alignment, improving charge extraction and reducing interfacial charge recombination. As a result, the photovoltaic performance can be efficiently improved from 10.50% to 12.32%. This work may provide new guidelines to the device structural design of QD optoelectronics by integrating different solution-processed semiconductors.