Boosting charge transport in lead chalcogenide quantum dots with short-wave infrared band gaps through anion composition engineering

Colloidal quantum dots (QDs) based on narrow band gap lead chalcogenides offer tunable absorption across the infrared spectrum, making them highly attractive for eye-safe short-wave infrared (SWIR) applications. Among lead chalcogenides, PbSe QDs exhibit exceptional charge transport properties, which are critical for high performance optoelectronic devices. However, their poor air stability and low chemical yield have markedly limited their broader deployment compared to PbS QDs. To overcome these limitations, ternary PbSe_xS_1−x QDs present a promising alternative by integrating the superior charge transport of PbSe QDs with the enhanced stability and chemical yield of PbS QDs. In this study, the controlled synthesis of monodisperse ternary PbSe_xS_1−x QDs is presented, achieved exclusively through the introduction of diphenylphosphine (DPP) as a key additive. The role of DPP in the formation of PbSe_xS_1−x QDs with controllable ternary composition is investigated, enabling precise control over the anionic composition of QDs with targeted absorption wavelengths in the SWIR region. Charge carrier mobility results revealed that ternary PbSe_xS_1−x QDs exhibit superior charge transport, attributed to the synergistic effects of optimal compositions and particle size. Furthermore, the ternary PbSe_xS_1−x QDs demonstrated a substantially improved chemical yield, particularly in compositions exhibiting the highest carrier mobility, underscoring their potential for practical implementation in optoelectronic applications.