Spray Pyrolysis Technique Enables Uniform Precursor Layer for Large-Area Flexible CZTSSe Solar Cells

Area of Science:

• Materials Science
• Renewable Energy

Background:

• Kesterite Cu₂ZnSn(S,Se)₄ (CZTSSe) is a key material for sustainable photovoltaics.
• Achieving high efficiency with low-cost CZTSSe fabrication is hindered by defect passivation challenges.

Purpose of the Study:

• To develop a feasible spray pyrolysis approach for high-quality CZTSSe absorber fabrication.
• To optimize processing parameters for enhanced CZTSSe solar cell performance and stability.

Main Methods:

• Spray pyrolysis technique was employed to deposit CZTSSe absorbers.
• Optimization of spray flow rate and substrate temperature to control precursor layer formation.
• Characterization of absorber crystallinity, surface morphology, and defect analysis using deep-level techniques.

Main Results:

• Optimized spray pyrolysis yielded dense, void-free CZTSSe with superior crystallinity and reduced surface roughness.
• Effective suppression of Cu/Zn cation disorder and band-tail states, resulting in low Urbach energy (33.98 meV).
• Achieved a 9.53% power conversion efficiency (PCE) for a 0.21 cm² CZTSSe solar cell and a 7.65% PCE for a 1.22 cm² large-area flexible device.

Conclusions:

• Spray pyrolysis offers a straightforward and scalable method for producing high-quality CZTSSe absorbers.
• Optimized CZTSSe solar cells demonstrate enhanced performance and good durability in flexible applications.
• This approach facilitates the development of efficient, large-area kesterite solar cells for sustainable energy.