Recent research published in APL Energy brings exciting new insight into the future of organic solar cells (OPVs). The study, titled “Slot-die coated bulk heterojunction vs layer-by-layer organic photovoltaics: Device architecture dependent degradation”, presents a direct comparison between bulk heterojunction (BHJ) and layer-by-layer (LBL) architectures, both fabricated via scalable slot-die coating by using FOM alphaSC coater. With precision and reproducibility in mind, the researchers from the University of Southern Denmark and the Technical University of Denmark not only advanced our understanding of OPV morphology but also demonstrated how equipment like the FOM alphaSC enables discoveries that could accelerate commercial viability.

(a) Conventional configuration of BHJ and LBL devices. (b) Inverted configuration of BHJ and LBL devices. (c) Schematic of slot-die-coating process. (d) Molecular structures of the donor material PM6 and the acceptor material Y7-12. Figure from the study.

OPVs have long held promise as a lightweight, flexible, and potentially low-cost alternative to traditional photovoltaics. However, transferring lab-scale performance into scalable manufacturing processes has posed significant challenges. Central to overcoming these is the ability to deposit high-quality thin films with exacting control—a challenge the study addressed using slot-die coating technology.

Slot-die coating offers exceptional advantages in terms of layer uniformity, low material waste, and compatibility with both rigid and flexible substrates. In this study, the researchers used the FOM alphaSC to fabricate all active layers, enabling systematic variation between BHJ and LBL configurations under identical process conditions. This control was vital to ensure fair, reproducible comparisons and draw conclusions that could guide future OPV development.

Importantly, the study demonstrated that high-efficiency OPVs can be fabricated using ambient processing conditions and green solvents, thanks to the reliability and consistency of the slot-die method. This approach supports the move toward environmentally sustainable production.

J–V plots of BHJ and LBL slot-die air-processed devices: (a) conventional configuration and (b) inverted configuration. EQE spectra of BHJ and LBL devices: (c) conventional configuration and (d) inverted configuration. (e) Histogram showing the statistical distribution of device performance for all configurations. Figure from the study.

The precision of the FOM alphaSC enabled the researchers to fabricate reproducible thin films under highly controlled conditions. With its 2-axis motorized slot-die head positioning, integrated pump with software-controlled wet film thickness, and compatibility with fluids up to 20,000 cPs, the FOM alphaSC provided the perfect platform to test process variations and layer interactions.

Its ability to coat widths up to 500 mm while supporting rigid and flexible substrates gave the team maximum experimental flexibility. By leveraging its advanced automation features and intuitive graphical interface, the researchers efficiently varied parameters such as coating speed, head temperature, and film thickness—insights that directly influenced the study’s findings.

Furthermore, the FOM alphaSC’s seamless glove box and fume hood integration ensured a clean, stable environment for coating sensitive organic materials, eliminating contamination variables that often plague thin-film research.

The most striking outcome of the study is this: high-efficiency organic solar cells are achievable through scalable slot-die coating—regardless of whether a bulk heterojunction or layer-by-layer architecture is used. The researchers achieved power conversion efficiencies as high as 15.24%, demonstrating that slot-die coating is not just a scalable method—it is a performance-driven one as well.

• Mini-Module Fabrication: The study successfully fabricated a mini-module that achieved a PCE of 13.06%, further proving the process’s scalability from lab-scale to larger formats.

• Operational Stability: Inverted BHJ devices exhibited outstanding light stability, maintaining high performance for over 800 hours, a significant milestone for the reliability of OPVs.

• Versatility: The study confirmed that slot-die coating is suitable across different device architectures and processing conditions, making it a robust choice for research and pilot-scale production.

• Degradation Analysis: Thermal degradation pathways were traced primarily to transport layers and electrode interfaces, providing valuable direction for future material development.

This study underscores our mission at FOM Technologies—to empower researchers with tools that accelerate discovery, enhance reproducibility, and enable scale-up. The FOM alphaSC embodies this vision, serving as the backbone for advanced R&D in solar energy, batteries, printed electronics, and beyond.

Our machines enable precise, predictable, and repeatable coating processes, helping the scientific community unlock new innovations every day. We are proud to see our technology used in cutting-edge research that not only deepens fundamental understanding but also drives real-world impact.

Conclusion

This work reinforces the value of slot-die coating in advanced thin-film research and demonstrates the FOM alphaSC’s ability to support high-performance, scalable OPV device fabrication. As the renewable energy sector seeks flexible, efficient, and manufacturable alternatives, studies like this bring us one step closer to a more sustainable energy future.

Stay tuned to FOM Technologies for more breakthroughs from the world’s leading labs—and the slot-die coating tools powering them.