Lattice-Matched 2D Template Enables Efficient Cesium Tin Halide Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Cesium tin iodide (CsSnI3) is a promising lead-free perovskite solar cell (PSC) material with a suitable bandgap and thermal stability.
• Challenges include random crystallization and phase transitions (δ-CsSnI3) that limit photovoltaic performance and durability.
• Existing 2D perovskite templates often have lattice mismatches and unfavorable interactions with 3D CsSnI3.

Purpose of the Study:

• To develop phase-pure 2D/3D perovskite heterostructures for efficient and stable CsSnI3-based PSCs.
• To utilize lattice-matched 2D perovskite templates for oriented growth of 3D CsSnI3.
• To suppress the detrimental δ-CsSnI3 phase transition and improve photovoltaic performance.

Main Methods:

• Employing 2D perovskites with aromatic spacer cations for enhanced π-π stacking and reduced lattice mismatch with 3D CsSnI3.
• Inducing oriented growth of 2D/3D heterostructures along the (110) plane.
• Regulating crystallization kinetics and creating energy barriers to prevent δ-CsSnI3 formation.

Main Results:

• Achieved oriented growth of 2D/3D heterostructures with improved crystallographic compatibility.
• Suppressed the formation of the δ-CsSnI3 phase, leading to phase-pure CsSnI3 films.
• Optimized CsSnI3-based PSCs reached a champion power conversion efficiency (PCE) of 15.27% with a high open-circuit voltage (Voc) of 0.90 V.
• Demonstrated enhanced operational stability, retaining over 95% of initial PCE after 1280 hours of continuous illumination.

Conclusions:

• Lattice-matched 2D perovskite templates effectively control the growth and phase stability of 3D CsSnI3.
• The developed 2D/3D heterostructures significantly improve the efficiency and operational durability of lead-free PSCs.
• This approach offers a viable strategy for advancing stable and efficient inorganic perovskite solar cells.