Gradient Energy Alignment Engineering for Planar Perovskite Solar Cells with Efficiency Over 23

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Electron-transport layers (ETLs) are crucial for efficient perovskite solar cells (PSCs).
• Interfacial energy level mismatch in ETLs limits PSC performance, especially open-circuit voltage (V_OC).
• Optimizing ETLs is key to reducing energy loss and improving PSC efficiency.

Purpose of the Study:

• To develop a low-temperature processed In₂ O₃ /SnO₂ bilayer ETL for PSCs.
• To improve energy alignment and charge transfer at the perovskite/ETL interface.
• To enhance the overall efficiency and stability of perovskite solar cells.

Main Methods:

• Fabrication of a novel In₂ O₃ /SnO₂ bilayer ETL using low-temperature processing.
• Integration of the new ETL into planar perovskite solar cell devices.
• Characterization of perovskite film quality, interfacial properties, and device performance (efficiency, V_OC, stability).

Main Results:

• The In₂ O₃ /SnO₂ ETL resulted in uniform, compact perovskite films with low trap density.
• Enhanced charge transfer due to shallower conduction band alignment of In₂ O₃ minimized V_OC loss.
• Achieved a power conversion efficiency of 23.24% (certified 22.54%) and a high V_OC of 1.17 V.
• Devices demonstrated excellent stability, retaining 97.5% efficiency after 80 days and 91% after 180 hours of continuous illumination.

Conclusions:

• The In₂ O₃ /SnO₂ bilayer ETL effectively addresses interfacial energy level mismatch in PSCs.
• This ETL design leads to significant improvements in PSC efficiency, voltage, and operational stability.
• The developed ETL presents a promising pathway for advancing efficient and durable perovskite photovoltaic technology.