Gradient-band-gap strategy for efficient solid-state PbS quantum-dot sensitized solar cells

Area of Science:

• Materials Science
• Nanotechnology
• Renewable Energy

Background:

• Solid-state quantum-dot sensitized solar cells (QDSCs) are promising for renewable energy applications.
• Improving charge separation and open-circuit voltage (Voc) are key challenges for enhancing QDSC performance.

Purpose of the Study:

• To develop gradient-band-gap lead sulfide (PbS) quantum dots for improved solid-state QDSCs.
• To investigate the effect of gradient band-gap engineering on photovoltaic performance.

Main Methods:

• Fabrication of gradient-band-gap PbS quantum dots using a two-step spin-coating and successive ionic layer absorption and reaction (SILAR) method.
• Characterization of solid-state QDSCs with gradient and inverse gradient band-gap structures.
• Performance evaluation under 1 sun and 0.5 sun illumination.

Main Results:

• Gradient-band-gap PbS QDSCs achieved a higher Voc (0.70 V) and photoelectric conversion efficiency (PCE) (4.08%) compared to inverse gradient structures (Voc 0.59 V, PCE 1.69%).
• Optimized gradient-band-gap QDSCs reached a Voc of 0.65 V and a PCE of 6.29% under 1 sun.
• The highest PCE achieved was 7.21% under 0.5 sun illumination.

Conclusions:

• The SILAR method enables facile construction of gradient-band-gap PbS quantum dots.
• Gradient band-gap engineering is an effective strategy to enhance Voc and PCE in solid-state QDSCs.
• Achieved PCE of 6.29% represents a record for solid-state QDSCs fabricated via SILAR.