Enhanced Performance of PbS-quantum-dot-sensitized Solar Cells via Optimizing Precursor Solution and Electrolytes

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Quantum dot-sensitized solar cells (QDSCs) offer a promising alternative to traditional photovoltaics.
• Lead sulfide (PbS) quantum dots (QDs) are effective light absorbers for QDSCs.
• Optimizing QD synthesis and electrolyte properties is crucial for enhancing QDSC performance.

Purpose of the Study:

• To optimize the synthesis of PbS QDs for QDSCs using the SILAR method.
• To improve the power conversion efficiency (PCE) and stability of PbS QDSCs.
• To investigate the effect of precursor concentration and electrolyte composition on QDSC performance.

Main Methods:

• PbS QDs were synthesized on mesoporous TiO2 films via the successive ion layer absorption and reaction (SILAR) method.
• The concentration of the precursor solution was systematically varied to determine optimal growth conditions.
• Polysulfide electrolyte composition was modified by replacing deionized water with methanol to enhance electrolyte properties.

Main Results:

• The optimal precursor concentration for QD synthesis was found to be 0.06 M, yielding desirable QD quantity and size.
• Replacing 30% of deionized water in the polysulfide electrolyte with methanol improved wettability and permeability.
• The modified electrolyte accelerated redox couple diffusion, improved charge transfer, and enhanced PbS QD stability, leading to a PCE of 4.01%.

Conclusions:

• Precursor concentration significantly impacts PbS QD growth and morphology.
• Methanol addition to the electrolyte enhances QDSC performance and stability by improving interfacial charge transfer and reducing recombination.
• The optimized QDSC fabrication process demonstrates a viable route towards higher efficiency solar cells.