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

Abstract 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.