Regulating strain in perovskite thin films through charge-transport layers

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Thermally-induced tensile strain in perovskite films increases ion migration, leading to instability in perovskite solar cells (PSCs).
• Existing strain regulation methods limit processing temperatures and reduce power conversion efficiency.

Purpose of the Study:

• To compensate residual tensile strain in PSCs by introducing external compressive strain.
• To enhance the stability and power conversion efficiency of perovskite solar cells.

Main Methods:

• Introducing compressive strain using a hole-transport layer with a high thermal expansion coefficient.
• Elevating the processing temperature of the hole-transport layer to compensate tensile strain.
• Investigating the effect of compressive strain on ion migration activation energy.

Main Results:

• Compressive strain increases the activation energy for ion migration, significantly improving perovskite film stability.
• Compressively-strained PSCs achieved a power conversion efficiency of 16.4%.
• These PSCs retained 96% of their initial efficiency after 1000 hours at 85°C, demonstrating remarkable stability.

Conclusions:

• External compressive strain is an effective strategy to mitigate ion migration and enhance the operational stability of PSCs.
• This method overcomes limitations of previous strain regulation techniques, enabling higher processing temperatures and improved efficiency.
• The developed wide-bandgap perovskite solar cells represent the most stable reported to date for this class of materials.