Stable Electron-Transport-Layer-Free Perovskite Solar Cells with over 22% Power Conversion Efficiency

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Electron-transport-layer-free (ETL-free) perovskite solar cells (PSCs) offer cost and production advantages.
• ETL-free PSCs suffer from significant charge carrier recombination at the perovskite/anode interface, limiting performance.
• Conventional n-i-p structured PSCs generally show superior performance.

Purpose of the Study:

• To develop a strategy for fabricating stable ETL-free FAPbI3 PSCs.
• To address the charge carrier recombination issue in ETL-free PSCs.
• To enhance the power conversion efficiency (PCE) of ETL-free PSCs.

Main Methods:

• In situ formation of a low-dimensional perovskite interlayer between FTO and the main perovskite layer.
• Fabrication of ETL-free FAPbI3 PSCs incorporating the interlayer.
• Characterization of the interlayer's effect on energy band bending, defect density, and energy level alignment.

Main Results:

• The interlayer induced energy band bending and reduced defect density in the perovskite film.
• Indirect contact and improved energy level alignment were achieved between the anode and perovskite.
• Charge carrier transport and collection were facilitated, suppressing recombination.
• ETL-free PSCs achieved a power conversion efficiency (PCE) exceeding 22% under ambient conditions.

Conclusions:

• The in situ formed low-dimensional perovskite interlayer is an effective strategy for enhancing ETL-free PSC performance.
• This approach significantly suppresses charge carrier recombination at the perovskite/anode interface.
• Stable and high-efficiency ETL-free PSCs (PCE > 22%) are achievable, paving the way for cost-effective solar technology.