Hard Lewis Base-Driven Crystallization Control for Efficient All-Perovskite Tandem Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• All-perovskite tandem solar cells (APTSCs) offer higher theoretical efficiencies and broader spectral coverage.
• Tin-lead (Sn-Pb) hybrid perovskite solar cells (PSCs), used as the bottom cell in APTSCs, suffer from high defect density and poor crystallization, limiting performance and stability.

Purpose of the Study:

• To address the challenges in Sn-Pb PSCs by developing a novel strategy for defect passivation and crystallization control.
• To enhance the performance and long-term stability of both single-junction Sn-Pb PSCs and APTSCs.

Main Methods:

• A Lewis hard-basicity amplification strategy was employed to create additional hard-acid binding sites.
• This strategy promotes coordination with Sn²⁺ ions, facilitating defect passivation and regulating crystallization morphology.
• The strategy was applied to single-junction Sn-Pb PSCs and subsequently integrated into APTSCs with wide-bandgap perovskites.

Main Results:

• Single-junction Sn-Pb PSCs achieved a champion power conversion efficiency (PCE) of 23.71%.
• All-perovskite tandem solar cells (APTSCs) fabricated with these Sn-Pb PSCs reached a champion PCE of 29.44%.
• Both device types demonstrated remarkable stability, retaining approximately 80% of their initial efficiency after 1080 hours of continuous one-sun illumination.

Conclusions:

• The Lewis hard-basicity amplification strategy is effective for defect passivation and crystallization control in Sn-Pb PSCs.
• This approach significantly enhances the PCE of both single-junction and tandem perovskite solar cells.
• The improved devices exhibit promising long-term operational stability, paving the way for practical applications.