Trioctylphosphine-Induced Surface Engineering of PbS Quantum Dots for High-Detectivity Short-Wave Infrared Photodiodes

PbS quantum dots (QDs) are promising materials for short-wave infrared (SWIR) photodetectors due to their tunable bandgap and broad spectral absorption. This study explores the impact of trioctylphosphine (TOP)-mediated surface reconstruction on PbS QDs, revealing that the TOP treatment enhances QD surface morphology, reduces trap states, and improves QD stacking behavior in solid films. Notably, a diode-type photodetector based on TOP-treated QDs exhibits a significantly enhanced specific detectivity ( D *) of 2.07 × 10 11 Jones at 1290 nm, which is 50 times higher than that of devices using conventional QDs. It also shows a marked reduction in dark current density to 237 nA cm −2 at −0.5 V. Furthermore, the TOP-QD photodetector demonstrates improved storage stability under non-encapsulated conditions, underscoring the effectiveness of TOP-mediated surface reconstruction in enhancing both performance and reliability. This work offers valuable insights into the surface engineering of PbS QDs and presents a pathway for the development of high-performance, solution-processed SWIR imaging systems and environmental monitoring technologies.