Improving organic tandem solar cells based on water-processed nanoparticles by quantitative 3D nanoimaging

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Organic solar cells offer sustainable energy potential through scalable roll-to-roll processing.
• Water-dispersible Landfester particles aid in controlled layer formation for industrial printing applications.
• Reducing organic solvent use is a key trend in the printing industry.

Purpose of the Study:

• To quantitatively image and analyze the 3D morphology of a roll-to-roll coated organic photovoltaic tandem stack.
• To identify structural defects in active layers, specifically those utilizing Landfester particles.
• To evaluate the impact of a polymer top coating on layer morphology and device performance.

Main Methods:

• Ptychographic X-ray computed tomography (PXCT) was employed for high-resolution 3D imaging.
• Quantitative analysis of layered morphology, porosity, and electrode structure was performed.
• Comparison of Landfester particle layer morphology before and after polymer top coating.

Main Results:

• PXCT successfully resolved the layered structure, porosity, and silver electrode of the tandem solar cell.
• The as-coated Landfester particle layer exhibited defects: poor interface correlation, variable thickness, and incomplete coverage, leading to electrical shorts.
• A polymer top coating effectively eliminated defects like porosity and roughness in the Landfester layer.

Conclusions:

• Quantitative imaging of organic stacked layers using PXCT is feasible and provides unique insights.
• Landfester nanoparticle layer formation requires improvement for optimal solar cell fabrication.
• Addressing structural defects via polymer top coating significantly enhances tandem organic solar cell performance beyond 1 V.