CuCl₂-modified SnO₂electron transport layer for high efficiency perovskite solar cells

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Tin oxide (SnO2) is a common electron transport layer (ETL) in perovskite solar cells (PSCs).
• Surface defects and energy level misalignment in SnO2 limit PSC efficiency.
• Additives can improve SnO2 ETL properties for better photovoltaic performance.

Purpose of the Study:

• To investigate the effect of anhydrous copper chloride (CuCl2) as an additive for modifying SnO2 ETLs in PSCs.
• To enhance the surface properties and energy level alignment of SnO2 ETLs.
• To improve the overall power conversion efficiency (PCE) and stability of PSCs.

Main Methods:

• Modification of SnO2 ETLs with anhydrous copper chloride (CuCl2).
• Characterization of SnO2-CuCl2 ETL properties, including Sn4+ proportion, surface defects, hydrophobicity, and conductivity.
• Fabrication and testing of PSCs using modified SnO2-CuCl2 ETLs.
• Comparative analysis with PSCs using pristine SnO2 ETLs and Cu(NO3)2 modified ETLs.

Main Results:

• CuCl2 modification improved the Sn4+ ratio in SnO2 and passivated oxygen vacancies.
• The modified ETL exhibited enhanced hydrophobicity and conductivity, with better energy level alignment with perovskite.
• PSCs with SnO2-CuCl2 ETLs showed a higher optimal PCE of 20.31% compared to control devices (18.15%).
• Unencapsulated PSCs maintained 89.3% of their initial PCE after 16 days of ambient exposure.
• Copper(II) nitrate (Cu(NO3)2) yielded similar improvements, indicating the role of the Cu2+ cation.

Conclusions:

• CuCl2 is an effective additive for enhancing SnO2 ETLs in PSCs.
• The modification strategy leads to improved charge transport, reduced recombination, and increased device stability.
• The cation Cu2+ plays a key role in the beneficial modification of SnO2 ETLs for high-performance PSCs.