Gradient Doping Strategy for Sn─Pb Mixed Perovskite Solar Cells with High Efficiency and Stability

Area of Science:

• Materials Science
• Photovoltaics
• Chemistry

Background:

• Tin-lead (Sn-Pb) hybrid perovskites offer promising bandgaps and photoelectric properties for solar applications.
• Challenges include Sn²⁺ oxidation and poor crystallinity, hindering device performance and stability.

Purpose of the Study:

• To develop a high-crystalline Sn-Pb mixed perovskite with enhanced stability and photoelectric properties.
• To address the oxidation and decomposition issues associated with Sn²⁺ doping in perovskite solar cells.

Main Methods:

• Utilized solvent engineering and formic acid (HCOOH) co-optimization for Sn²⁺ doping in Pb-based perovskites.
• Employed atomic layer deposition (ALD) to create a compact SnO₂ electron transport layer.
• Combined experimental and theoretical analyses to understand material interactions and properties.

Main Results:

• Achieved high crystallinity and larger grain size in Sn-Pb perovskite films.
• HCOOH effectively prevented Sn²⁺ oxidation and A-site cation decomposition.
• Reduced defect density, improved film crystallinity, and enhanced stability.
• Prepared Sn─Pb hybrid perovskite solar cells (PSCs) with a photoelectric conversion efficiency of 21.53%.

Conclusions:

• The developed dopant growth method significantly improves the stability of Sn-Pb PSCs compared to traditional methods.
• The synergistic effects of Sn²⁺ doping, HCOOH treatment, and SnO₂ ETL are crucial for high-performance and stable perovskite solar cells.