Title:
Synthesis of Cu₃VS₄ Quantum Dots and Their Application in Quantum Dot Sensitized Solar Cells (QDSSCs)
Abstract:
This work reports the synthesis of copper vanadium sulfide (Cu₃VS₄) quantum dots (QDs) via a simple colloidal method and explores their potential application in quantum dot sensitized solar cells (QDSSCs). The Cu₃VS₄ QDs exhibit tunable optical properties, narrow size distribution, and a suitable bandgap for light harvesting in the visible region. Structural, morphological, and optical characterizations were carried out using techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis spectroscopy. The QDs were employed as sensitizers in solar cell devices using TiO₂ photoanodes. The photovoltaic performance was evaluated, showing promising power conversion efficiency and stability. This study suggests that Cu₃VS₄ QDs are a viable, cost-effective alternative to traditional toxic or rare metal-based QDs for solar energy conversion.
Introduction:
Quantum dot sensitized solar cells (QDSSCs) have attracted increasing attention due to their tunable bandgaps, high absorption coefficients, and potential for multiple exciton generation. Transition metal chalcogenide QDs, such as Cu-based compounds, offer the added advantages of low toxicity and earth-abundance. Cu₃VS₄ is a ternary metal sulfide with desirable optoelectronic properties, making it a potential candidate for solar energy applications. However, its use in QDSSCs has been underexplored. This study aims to synthesize Cu₃VS₄ QDs and assess their performance in sensitizing TiO₂-based solar cells.
Experimental Section:
Materials:
Copper acetate, vanadium pentoxide, thiourea, oleylamine, and other solvents were used without further purification.
Synthesis of Cu₃VS₄ QDs:
Cu₃VS₄ QDs were synthesized via a hot-injection method. Copper acetate and vanadium precursors were dissolved in oleylamine under inert atmosphere and heated to 180–220°C. Thiourea was swiftly injected, leading to the formation of dark-colored Cu₃VS₄ colloidal QDs. After growth, the reaction was quenched, and the QDs were purified via centrifugation and solvent washing.
Characterization:
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XRD: Confirmed the crystalline structure corresponding to tetragonal Cu₃VS₄.
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TEM: Revealed spherical QDs with average diameters of ~5–8 nm.
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UV-Vis and PL spectroscopy: Showed absorption onset in the visible range (~500–700 nm), suitable for solar harvesting.
QDSSC Fabrication:
A TiO₂ mesoporous layer was deposited on FTO glass substrates, followed by sensitization with Cu₃VS₄ QDs via a ligand exchange and dipping process. A polysulfide electrolyte and a counter electrode (e.g., platinum-coated FTO) completed the device architecture.
Results and Discussion:
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The synthesized Cu₃VS₄ QDs exhibited size-dependent optical properties, confirming successful quantum confinement.
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Bandgap estimated from Tauc plot was in the range of 1.8–2.2 eV, ideal for visible light absorption.
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Photovoltaic measurements showed open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) in the range of comparable chalcogenide QDs, demonstrating their capability in solar cell applications.
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The use of Cu₃VS₄ reduces environmental concerns due to its lower toxicity compared to Cd or Pb-based QDs.
Conclusion:
Cu₃VS₄ quantum dots were successfully synthesized and integrated into QDSSCs, demonstrating promising optoelectronic properties and solar energy conversion performance. Their earth-abundant and environmentally benign nature makes them a potential alternative for next-generation solar technologies. Further optimization of surface passivation and device architecture is expected to enhance their efficiency.
