In Situ Dual-Interface Modulation for Homogeneous Sn─Pb Perovskites and Efficient Tandem Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• All-perovskite tandem solar cells (TSCs) offer high efficiency and low cost but are limited by narrow-bandgap bottom subcells.
• Challenges in tin-lead (Sn─Pb) perovskite subcells include uncontrolled crystallization, Sn²⁺ oxidation issues, and poor band alignment.

Purpose of the Study:

• To address performance limitations in Sn─Pb perovskite solar cells (PSCs) for enhanced TSCs.
• To develop an in situ dual-interface modulation strategy for improved perovskite crystallization, stability, and charge transport.

Main Methods:

• Incorporation of planar rigid tetrathiafulvalene (TTF) into the Sn─Pb perovskite precursor solution.
• In situ self-assembly of TTF at dual interfaces to modulate crystallization dynamics and homogenize Sn oxidation states.
• Evaluation of carrier extraction, transport, and structural stabilization within the perovskite layer and interfaces.

Main Results:

• Achieved a champion power conversion efficiency (PCE) of 24.30% for single-junction Sn─Pb PSCs with a record fill factor of 83.59%.
• Demonstrated a high PCE of 29.14% (certified 29.07%) in all-perovskite TSCs utilizing the modified Sn─Pb bottom subcells.
• The encapsulated tandem device retained 80% of its initial efficiency after 964 hours of stability testing under simulated sunlight.

Conclusions:

• The in situ dual-interface modulation strategy effectively enhances the performance and stability of Sn─Pb PSCs.
• This approach significantly advances the development of efficient and stable all-perovskite tandem solar cells.
• TTF incorporation offers a promising pathway for overcoming key challenges in perovskite photovoltaic technology.