Developing Scalable and Sustainable Organic Solar Cells

Organic photovoltaics (OPVs) have emerged as a promising technology for renewable energy generation due to their potential for flexible form factors and scalable fabrication. Emerging photovoltaic research tends to prioritize device efficiency over scalability, focusing on spin-coated small-area devices, often relying on halogenated solvents such as chloroform or chlorobenzene to dissolve blends of organic semiconductors. These halogenated solvents are toxic to both the environment and human health. In this work, we demonstrate OPVs with layers deposited with blade-coating, a scalable and less wasteful method. In addition, active layers are processed with anisole as an eco-friendly alternative solvent. For blade-coating layers, we optimized blade speed to demonstrate that printed interlayers can achieve comparable performance to spun interlayers in OPVs. The printed-interlayer devices show efficiency of 3.7% as compared to the 3.3% efficiency obtained for spun devices. The material loading in anisole-based active ink formulation is optimized to achieve equivalent solution viscosity and absorbance as obtained with chlorinated solvents. In situ absorbance characterization of film drying and 2D GIWAXS measurements are used to confirm improved film morphology when increasing material loading and employing thermal annealing, resulting in increased performance. These results indicate the potential for scalable fabrication with sustainable materials without compromising OPV performance.