Solid-State Crystallization Regulation Enables High-Performance Thermally Evaporated CsPbI₂Br Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Thermal evaporation shows promise for scalable inorganic perovskite solar cells (PSCs).
• Current limitations include poor crystallization control, defects, and unclear mechanisms in CsPbI₂Br devices.
• Optimizing solid-state crystallization is crucial for high-performance PSCs.

Purpose of the Study:

• To develop an effective strategy for regulating solid-state crystallization in thermally evaporated CsPbI₂Br.
• To investigate the role of a molecular regulator in controlling precursor diffusion and grain growth.
• To enhance the performance and scalability of inorganic perovskite solar cells.

Main Methods:

• Employed dibenzo-18-crown-6 (DC) as a transient crystallization modulator during thermal evaporation.
• Utilized in situ measurements to observe the coordination of DC with Pb²⁺ and its effect on nucleation and diffusion.
• Fabricated and characterized CsPbI₂Br films and solar cells using the modified deposition process.

Main Results:

• DC successfully retarded solid-state nucleation, promoting complete precursor diffusion and ordered grain growth.
• DC-modified CsPbI₂Br films exhibited enhanced crystallinity, larger grain size, reduced trap density, and improved optoelectronic properties.
• Achieved a champion power conversion efficiency of 15.85% for CsPbI₂Br PSCs, the highest reported for this method, with scalable large-area patterning.

Conclusions:

• The DC-mediated crystallization strategy effectively improves the quality of thermally evaporated CsPbI₂Br films.
• This approach overcomes key limitations in solid-state crystallization, leading to record efficiencies for thermally evaporated PSCs.
• The method is compatible with industry manufacturing and enables scalable, patterned perovskite film fabrication.