Colloidal Quantum Dot Solid-Based Infrared Optoelectronics Enabled by Solution-Phase Ligand Exchange

This study explores the rational strategy to build lead sulfide (PbS)-based colloidal quantum dots (CQDs) solid for high performance photodetection and solar energy conversion in the near- and short-wave infrared spectra. We demonstrated a facile engineering process from CQD synthesis to infrared CQD devices fabrication. By controlling the monomer concentration, we effectively tuned the infrared absorption characteristics and the solution-phase surface ligand exchange resulted in highly concentrated CQD ink, facilitating the formation of uniform, and thick CQD solids, which is crucial for high absorption efficiency. The CQD-based infrared photodetector achieved a specific detectivity of approximately 10 11 Jones and fast response times under 100 ns. Furthermore, optimized PbS CQDs were utilized in solar cells and achieved high quantum efficiency across visible to infrared spectrum, indicating a significant potential for 2-terminal tandem structures with perovskite front cells.