Efficient Wide-Bandgap Mixed-Cation and Mixed-Halide Perovskite Solar Cells by Vacuum Deposition

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Vacuum deposition offers low-temperature processing for multilayer perovskite devices.
• Wide-bandgap perovskite solar cells are challenging to fabricate using vacuum deposition due to multi-source complexities.

Purpose of the Study:

• To develop a four-source vacuum deposition process for wide-bandgap perovskite films.
• To achieve tunable bandgaps and controlled morphology in mixed-cation and mixed-anion perovskites.
• To fabricate and assess the performance and stability of resulting solar cells.

Main Methods:

• Utilized a four-source vacuum deposition technique with FAI, CsI, PbI2, and PbBr2 precursors.
• Employed simultaneous sublimation of PbI2 and PbBr2 to control halide and cation composition.
• Fabricated perovskite films with a tunable bandgap in the 1.7-1.8 eV range.

Main Results:

• Achieved homogeneous perovskite films (FA1-xCaxPb(I1-yBry)3) with no detectable halide segregation.
• Demonstrated tunable bandgaps between 1.7-1.8 eV.
• Fabricated solar cells with a 1.75 eV bandgap achieved up to 16.8% efficiency.
• Observed promising operational stability, retaining 90% of initial efficiency after 2 weeks.

Conclusions:

• The four-source vacuum deposition method is effective for producing high-quality, wide-bandgap perovskite films.
• This technique facilitates the development of efficient and stable perovskite solar cells with tailored properties.
• The ability to decouple cation and anion composition is crucial for advanced perovskite device fabrication.