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<p>Silver selenide (Ag₂Se) quantum dots (QDs) were synthesized using a controlled chemical precipitation process and thoroughly investigated for their use as light-harvesting material in quantum dot-sensitized solar cells (QDSSCs). To improve the restricted performance of Ag₂Se-based device architectures, CdS and CdSe quantum dots were added as co-sensitization layers in fabrication of multilayer heterostructure photoanodes to allow maximum energy levels alignment. Physical and chemical characterization of the as-prepared Ag₂Se QDs were carried out using different methods including UV–Vis spectroscopy, cyclic voltammetry (CV), FTIR, XRD, FESEM, and EDX analyses and confirmed their nanocrystallite structure, appropriate band gap energy (1.58 eV) and efficient surface capping by TGA and PVP ligands. It was shown that the sequential sensitization with TiO₂, CdS and CdSe extended the absorption spectrum from the ultraviolet to near-infrared region. Additionally, FESEM and EDX analyses supported the existence of stable and uniform surface coverage along with multilayer growth, while the XRD analysis affirmed the co-existence of TiO₂, CdS, Ag₂Se, and CdSe crystal phases without any structural disruption. Photovoltaic measurements revealed that the reference TiO₂/Ag₂Se device possessed considerably poor characteristics mainly due to the internal recombination phenomena. The incorporation of CdS QDs layer caused improvements in light absorption, band alignment and charge separation and resulted in PCE of η = 0.120% for optimized TiO₂/CdS/Ag₂Se photoanode structure. Further application of the CdSe QDs layer generated stronger light absorption and proper band alignment. It was finally shown that the optimized QDSSC with TiO₂/CdS(6)/Ag₂Se/CdSe photoelectrode possessed improved PV parameters and an increase about 141% in power conversion efficiency.</p>

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Investigation of Ag₂Se quantum dots for application in QDSSCs and performance optimization via the co-sensitization approach

  • 期刊论文

  • 发表日期：

    2026年6月22日

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  • Elnaz Sedighi,
  • Alireza Eftekhari,
  • Maziar Marandi

摘要

Silver selenide (Ag₂Se) quantum dots (QDs) were synthesized using a controlled chemical precipitation process and thoroughly investigated for their use as light-harvesting material in quantum dot-sensitized solar cells (QDSSCs). To improve the restricted performance of Ag₂Se-based device architectures, CdS and CdSe quantum dots were added as co-sensitization layers in fabrication of multilayer heterostructure photoanodes to allow maximum energy levels alignment. Physical and chemical characterization of the as-prepared Ag₂Se QDs were carried out using different methods including UV–Vis spectroscopy, cyclic voltammetry (CV), FTIR, XRD, FESEM, and EDX analyses and confirmed their nanocrystallite structure, appropriate band gap energy (1.58 eV) and efficient surface capping by TGA and PVP ligands. It was shown that the sequential sensitization with TiO₂, CdS and CdSe extended the absorption spectrum from the ultraviolet to near-infrared region. Additionally, FESEM and EDX analyses supported the existence of stable and uniform surface coverage along with multilayer growth, while the XRD analysis affirmed the co-existence of TiO₂, CdS, Ag₂Se, and CdSe crystal phases without any structural disruption. Photovoltaic measurements revealed that the reference TiO₂/Ag₂Se device possessed considerably poor characteristics mainly due to the internal recombination phenomena. The incorporation of CdS QDs layer caused improvements in light absorption, band alignment and charge separation and resulted in PCE of η = 0.120% for optimized TiO₂/CdS/Ag₂Se photoanode structure. Further application of the CdSe QDs layer generated stronger light absorption and proper band alignment. It was finally shown that the optimized QDSSC with TiO₂/CdS(6)/Ag₂Se/CdSe photoelectrode possessed improved PV parameters and an increase about 141% in power conversion efficiency.