Interfacial Characteristics of Efficient Bulk Heterojunction Solar Cells Fabricated on MoOx Anode Interlayers

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Organic solar cells utilize polymer:fullerene bulk heterojunctions for light absorption and charge generation.
• Anode interlayers, such as molybdenum oxide (MoOx), play a critical role in efficient charge extraction.
• The interface between the anode interlayer and the bulk heterojunction significantly impacts device performance.

Purpose of the Study:

• To investigate the role of the MoOx anode interlayer interface in polymer:fullerene bulk heterojunction solar cells.
• To determine the key factors influencing device performance related to the MoOx interface.
• To establish a reliable predictor for device efficiency based on interface properties.

Main Methods:

• Fabrication of polymer:fullerene bulk heterojunction films with varying MoOx anode interlayer processing.
• Characterization of the vertical stratification of the bulk heterojunction films.
• Quantification of polymer chemisorption to the MoOx anode interlayer.
• Correlation of interface properties with measured device performance.

Main Results:

• Processing variations in the MoOx interlayer lead to significant changes in bulk heterojunction vertical stratification.
• Vertical stratification alone is an unreliable indicator of device performance.
• The quantity of polymer chemisorbed to the MoOx anode interlayer strongly correlates with improved device performance.
• Chemisorption appears to be a more critical factor than morphological stratification.

Conclusions:

• The chemical interaction (chemisorption) between the polymer and the MoOx anode interlayer is a dominant factor in determining organic solar cell performance.
• Device optimization should focus on maximizing polymer chemisorption to the anode interlayer.
• Understanding and controlling interfacial chemistry is key for advancing polymer:fullerene solar cell technology.