Open Access

ARTICLE

Bandgap Tunable PbSnSeS Quaternary Quantum Dots for near-Infrared Optoelectronic and Solar Cell Applications

M. Irshad Ahamed^1,*, P. J. Suresh Babu², R. Lal Raja Singh³, S. Sivamani², R. Leena Rose⁴

1 Department of Electronics and Communication Engineering, E.G.S. Pillay Engineering College, Nagapattinam, Tamilnadu, India
2 Department of Electrical and Electronics Engineering, E.G.S. Pillay Engineering College, Nagapattinam, Tamilnadu, India
3 Department of Electrical and Electronics Engineering, KIT-Kalaignarkarunanidhi Institute of Technology, Coimbatore, Tamilnadu, India
4 Department of Electrical and Electronics Engineering, Sri Ranganathar Institute of Engineering and Technology, Coimbatore, Tamilnadu, India

* Corresponding Author: M. Irshad Ahamed. Email:

Chalcogenide Letters 2026, 23(7), 2 https://doi.org/10.32604/cl.2026.084991

Received 03 May 2026; Accepted 29 June 2026; Issue published 07 August 2026

Abstract

Semiconductor quantum dots (QDs) with tunable narrow bandgaps have emerged as promising materials for next-generation near-infrared (NIR) optoelectronic and photovoltaic devices because their optical properties can be tailored through composition and quantum confinement. Among IV–VI chalcogenide nanomaterials, quaternary alloy systems provide greater compositional flexibility than conventional binary and ternary counterparts; however, PbSnSeS quantum dots remain largely unexplored despite their potential for broadband infrared applications. Here, the structural, electronic, and optical properties of PbSnSeS quaternary QDs synthesized by a one-pot colloidal hot-injection method are systematically investigated. The crystalline IV–VI chalcogenide phase and successful quaternary alloy formation were confirmed by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX), while scanning electron microscopy (SEM) revealed particle sizes in the range of 6–20 nm. The composition- and size-dependent optical behavior was further interpreted using the L.E. Brus model, hyperbolic band model, compositional bandgap estimation, exciton Bohr radius analysis, and density-of-states (DOS) calculations. UV–Vis–NIR spectroscopy exhibited a strong absorption peak at approximately 1675 nm, corresponding to an optical bandgap of 0.74 eV, whereas photoluminescence measurements showed intense NIR emission centered near 1650 nm with a relatively narrow linewidth. The combined theoretical and experimental results demonstrate tunable optical characteristics spanning the visible to near-infrared spectral region. Although lead-containing quantum dots raise environmental concerns, partial substitution of Pb with Sn provides a comparatively lead-reduced alloy while retaining favorable narrow-bandgap optical properties. Overall, the findings identify PbSnSeS quaternary quantum dots as promising candidates for near-infrared optoelectronics, infrared photonics, and next-generation tandem solar cell applications.

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