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<p>Quantum dots with tunable emission and charge storage behavior had offered routes for sensing and lighting, yet composition–defect control remained challenging. Zinc sulfide, a wide-band-gap semiconductor, had benefited from dopant engineering, but the effects of Sn/Cr codoping on structure–property relations had not been clarified. This study addressed that gap by establishing how processing-controlled composition governed phase formation, lattice evolution, and functional responses in ZnS quantum dots. The objective was to locate a composition window that maximized optical emission, interfacial kinetics, and thermal stability. A room-temperature coprecipitation route at pH ~ 9.5 produced ZnS codoped with fixed Sn<sup>2+</sup> and graded Cr<sup>3+</sup> (<i>x</i> = 0–0.06); characterization included XRD, FTIR/XPS, UV–Vis/Tauc, PL, TG/DSC, CV, and EIS. XRD confirmed zinc-blende ZnS with (111)/(220)/(311) reflections, and progressive 2θ shifts with Cr indicated lattice contraction consistent with substitutional Cr<sup>3+</sup> at Zn<sup>2+</sup> sites. Crystallites measured 2.6–4.4&#xa0;nm, and the optical band gap narrowed from ~ 4.01&#xa0;eV (Sn only) to ~ 2.99&#xa0;eV at <i>x</i> = 0.06. PL bands near 375&#xa0;nm, 455&#xa0;nm, 483&#xa0;nm, 521&#xa0;nm, 608&#xa0;nm, and 668&#xa0;nm changed in intensity with Cr, reflecting defect rebalancing. Electrochemical testing recorded a capacitance rise from ~ 115 mF g⁻<sup>1</sup> to ~ 700–782 mF g⁻<sup>1</sup> at <i>x</i> = 0.02–0.04, and EIS indicated reduced charge transfer resistance; TG showed improved mass retention near <i>x</i> ≈ 0.04. These results demonstrated that codoping and mild processing tuned defect states and transport. The materials held potential for luminescent components and electrode-relevant charge storage. Further investigation was needed to translate the optimum into device-level performance and to assess long-term stability under operating conditions.</p>

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Coprecipitation Processing and Structure–Property Optimization of Zn0.9−xS:(Sn0.1,Crx) Quantum Dots for Functional Material Applications (x = 0–0.06)

  • 期刊论文

  • 发表日期：

    2026年1月20日

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  • A. Krishnamoorthy,
  • I. Devadoss,
  • V. M. Rajavel Muthaiah,
  • Mohan Govindasamy,
  • Ratchagaraja Dhairiyasamy

摘要

Quantum dots with tunable emission and charge storage behavior had offered routes for sensing and lighting, yet composition–defect control remained challenging. Zinc sulfide, a wide-band-gap semiconductor, had benefited from dopant engineering, but the effects of Sn/Cr codoping on structure–property relations had not been clarified. This study addressed that gap by establishing how processing-controlled composition governed phase formation, lattice evolution, and functional responses in ZnS quantum dots. The objective was to locate a composition window that maximized optical emission, interfacial kinetics, and thermal stability. A room-temperature coprecipitation route at pH ~ 9.5 produced ZnS codoped with fixed Sn2+ and graded Cr3+ (x = 0–0.06); characterization included XRD, FTIR/XPS, UV–Vis/Tauc, PL, TG/DSC, CV, and EIS. XRD confirmed zinc-blende ZnS with (111)/(220)/(311) reflections, and progressive 2θ shifts with Cr indicated lattice contraction consistent with substitutional Cr3+ at Zn2+ sites. Crystallites measured 2.6–4.4 nm, and the optical band gap narrowed from ~ 4.01 eV (Sn only) to ~ 2.99 eV at x = 0.06. PL bands near 375 nm, 455 nm, 483 nm, 521 nm, 608 nm, and 668 nm changed in intensity with Cr, reflecting defect rebalancing. Electrochemical testing recorded a capacitance rise from ~ 115 mF g⁻1 to ~ 700–782 mF g⁻1 at x = 0.02–0.04, and EIS indicated reduced charge transfer resistance; TG showed improved mass retention near x ≈ 0.04. These results demonstrated that codoping and mild processing tuned defect states and transport. The materials held potential for luminescent components and electrode-relevant charge storage. Further investigation was needed to translate the optimum into device-level performance and to assess long-term stability under operating conditions.