Close-Space Sublimation as a Scalable Method for Perovskite Solar Cells.

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Vacuum techniques are crucial for scalable perovskite solar cell (PV) manufacturing.
• Industrial adaptability of vacuum methods for PV is underexplored.
• Close-space sublimation (CSS) is a widely used industrial technique with high material transfer and low pressures.

Purpose of the Study:

• To investigate the efficacy of close-space sublimation (CSS) for fabricating perovskite solar cells.
• To assess the scalability and industrial relevance of CSS for perovskite PV.
• To analyze the performance and stability of CSS-produced perovskite solar cells.

Main Methods:

• Utilized close-space sublimation (CSS) under rough vacuum (10 mbar) for perovskite layer deposition.
• Employed a reusable pressed pellet of formamidinium iodide (FAI) as the organic source.
• Conducted device characterization, including photoconversion efficiency (PCE) measurements and long-term thermal stress testing (>650 h at 85 °C).

Main Results:

• Achieved efficient cesium formamidinium lead iodide perovskite solar cells with a maximum PCE of 18.7%.
• Demonstrated excellent operational stability, maintaining performance for over 650 hours under thermal stress (85 °C in nitrogen).
• Identified a reduction in bulk trap density as the key factor for initial PCE enhancement upon heating, confirmed by drift-diffusion simulations.

Conclusions:

• CSS is a viable and scalable vacuum technique for producing high-efficiency and stable perovskite solar cells.
• The reusability of the FAI source pellet enhances the economic feasibility of the CSS method.
• Understanding the role of trap density dynamics is crucial for optimizing perovskite solar cell performance and stability.