Monday, October 6, 2025


 

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:

  • XRD: Confirmed the crystalline structure corresponding to tetragonal Cu₃VS₄.

  • TEM: Revealed spherical QDs with average diameters of ~5–8 nm.

  • 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:

  • The synthesized Cu₃VS₄ QDs exhibited size-dependent optical properties, confirming successful quantum confinement.

  • Bandgap estimated from Tauc plot was in the range of 1.8–2.2 eV, ideal for visible light absorption.

  • 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.

  • 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.

Saturday, October 4, 2025

Nanomaterials

 



What are nanomaterials?

Scientists have not unanimously settled on a precise definition of nanomaterials, but agree that they are partially characterized by their tiny size, measured in nanometers. A nanometer is one millionth of a millimeter - approximately 100,000 times smaller than the diameter of a human hair.

Nano-sized particles exist in nature and can be created from a variety of products, such as carbon or minerals like silver, but nanomaterials by definition must have at least one dimension that is less than approximately 100 nanometers. Most nanoscale materials are too small to be seen with the naked eye and even with conventional lab microscopes.

Materials engineered to such a small scale are often referred to as engineered nanomaterials (ENMs), which can take on unique optical, magnetic, electrical, and other properties. These emergent properties have the potential for great impacts in electronics, medicine, and other fields. For example,

  1. Nanotechnology can be used to design pharmaceuticals that can target specific organs or cells in the body such as cancer cells, and enhance the effectiveness of therapy.
  2. Nanomaterials can also be added to cement, cloth and other materials to make them stronger and yet lighter.
  3. Their size makes them extremely useful in electronics, and they can also be used in environmental remediation or clean-up to bind with and neutralize toxins. 

However, while engineered nanomaterials provide great benefits, we know very little about the potential effects on human health and the environment. Even well-known materials, such as silver for example, may pose a hazard when engineered to nano size.

Nano-sized particles can enter the human body through inhalation and ingestion and through the skin. Fibrous nanomaterials made of carbon have been shown to induce inflammation in the lungs in ways that are similar to Asbestos .


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  Title: Synthesis of Cu₃VS₄ Quantum Dots and Their Application in Quantum Dot Sensitized Solar Cells (QDSSCs) Abstract: This work repor...