Scalable Solution-Processed Hybrid Electron Transport Layers for Efficient All-Perovskite Tandem Solar Modules

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• All-perovskite tandem solar cells promise efficiencies beyond the Shockley-Queisser limit.
• Solution processing offers cost and productivity advantages over traditional methods.
• Scalable electron transport layer (ETL) fabrication for perovskite solar subcells remains a significant challenge.

Purpose of the Study:

• To develop a scalable solution-processed ETL for all-perovskite tandem solar modules.
• To address challenges related to perovskite film surface roughness and energy level mismatch.
• To improve the efficiency and stability of perovskite solar cells.

Main Methods:

• Development of hybrid fullerenes (HF) comprising fullerene (C60), phenyl C61 butyric acid methyl ester, and indene-C60 bisadduct.
• Blade-coating technique for applying HF as ETL on wide- and narrow-bandgap perovskite films.
• Characterization of HF properties, including conductivity and energy level alignment.

Main Results:

• Hybrid fullerenes demonstrated improved conductivity and superior energy level alignment compared to C60.
• Reduced interfacial nonradiative recombination was observed with HF ETLs.
• All-perovskite tandem solar modules achieved a champion power conversion efficiency of 23.3% over a 20.25 cm2 aperture area.

Conclusions:

• Scalable solution processing of hybrid fullerenes is a viable approach for ETLs in all-perovskite tandem solar modules.
• This method overcomes key fabrication challenges, enabling high-efficiency device performance.
• The study supports the future development of low-cost, high-efficiency, all-solution-processed perovskite tandem solar cells.