Compositional texture engineering for highly stable wide-bandgap perovskite solar cells.

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Wide-bandgap (WBG) perovskite solar cells (PSCs) are crucial for high-efficiency tandem devices.
• Bromine-iodine (Br-I) mixed-halide PSCs face challenges with Br-I phase segregation under operational conditions, limiting voltage and stability.
• Defect formation during rapid crystallization of Br-rich perovskites further hinders performance.

Purpose of the Study:

• To develop highly stable and efficient WBG PSCs using Br-I mixed-halide perovskite.
• To mitigate Br-I phase segregation and reduce defect density in perovskite films.
• To create efficient all-perovskite tandem solar cells.

Main Methods:

• Combined rapid Br crystallization with a gentle gas-quench method.
• Prepared highly textured columnar 1.75-electron volt Br-I mixed WBG perovskite films.
• Integrated WBG PSCs with narrow-bandgap PSCs into a two-terminal tandem device.

Main Results:

• Achieved 1.75-electron volt WBG PSCs with over 20% power conversion efficiency and 1.33-volt open-circuit voltage (Voc).
• Demonstrated excellent operational stability with less than 5% degradation over 1100 hours at 65°C under 1.2 sun.
• Fabricated a 27.1% efficient all-perovskite tandem solar cell with a 2.2-volt Voc.

Conclusions:

• The gas-quench method effectively produces stable, efficient WBG perovskite films by reducing defect density and phase segregation.
• The developed WBG PSCs are suitable for high-performance tandem solar cell applications.
• The all-perovskite tandem device shows significant potential for future solar energy conversion.