Boosting Charge Transport in Lead Chalcogenide Quantum Dots with Short-Wave Infrared Band Gaps through Anion Composition Engineering

Abstract

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 x S 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 x S 1-x QDs is presented, achieved exclusively through the introduction of diphenylphosphine (DPP) as a key additive. The role of DPP in synthesizing ternary PbSe x S 1-x QDs is elucidated, enabling precise control over anionic composition of QD with targeted absorption wavelengths in the SWIR region. Charge carrier mobility results revealed that ternary PbSe x S 1-x QDs exhibit superior charge transport, attributed to the synergistic effects of optimal compositions and particle size. Furthermore, the ternary PbSe x S 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.