Thick-film organic solar cells mapped for efficiency and production gains
Because laboratory single-junction organic solar photovoltaics (OPVs) now achieve an energy conversion efficiency of 20 percent, their performance still depends on thin photoactive layers near 100 nm. A new review led by Hangzhou Normal University and Zhejiang University investigates how high efficiency can be maintained in much thicker films suitable for industry.
The authors define thick-film OPVs as larger than 300 nm and describe benefits for scalable production, stronger near-infrared absorption, and improved mechanical robustness for flexible devices. They also identify the drawbacks: increased exciton recombination, unbalanced charge transport, and challenges in morphology control over film thickness.
Solutions are organized along the photovoltaic process. For exciton management, the review emphasizes molecular design of non-fullerene acceptors, sensible fluorinated additives, and tighter control of molecular packing to increase diffusion and promote dissociation in thicker layers.
For carrier transport, tactics are described to improve and balance the mobility of electrons and holes, including promoting molecular planarity and crystallinity and designing vertical phase separation that efficiently conducts charges to electrodes without impeding optical absorption.
To suppress recombination and promote extraction, the authors discuss side chain engineering, selection of solvent additives, and tuning the molecular weight of polymers to limit trap states and promote percolated pathways. Collectively, these approaches focus on thickness-tolerant architectures.
Reported results include thick-film devices exceeding 19 percent efficiency, with some systems maintaining strong performance above 500 nm active layers. Stability strategies such as entropy-driven stabilization and crystallization sequence control retain 80-90 percent of initial efficiency after 1000 hours of thermal aging.
Cost considerations include low-cost polymer donors such as PTQ10 and TVT-based materials, in addition to reduced material waste when processing thicker layers at scale. The piece also explores machine learning tools that accelerate materials screening and device optimization for thickness-agnostic OPVs.
The review, published in Nano-Micro Letters on July 23, 2025, provides practical guidance connecting laboratory breakthroughs to industrial manufacturing, from molecular engineering to device stack design and reliability testing.
Research report:Optimizing exciton and charge carrier behavior in organic thick film solar photovoltaics: a comprehensive review
