A new coating helps large organic solar modules reach certified 16.1% efficiency
The process creates a more uniform molecular layer and worked on 18.20-square-centimeter modules made with a blade-coating method.
Editorial illustration — not from the study.
The researchers combined donor molecules with hole-extraction molecules in an ultrathin preliminary coating. A specially designed set of carbazole-based molecules helped the components separate into a stable layered structure, reducing problems that can cause incomplete or uneven coverage as devices get larger.
The process worked with ambient blade coating and toluene-based processing. Small-area devices reached a best reported efficiency of 18.7%, while an 18.20-square-centimeter module achieved a certified efficiency of 16.1%.
What the coating does
The study introduces a Hole-Extraction Embedded Ultrathin Donor strategy, in which donor and hole-extraction molecules are deposited together before separating into distinct layers. The researchers designed four carbazole-based molecules, labeled K1 through K4, to control how readily the components mixed.
When K1 was confined in an almost 10-nanometer sacrificial donor layer, it rapidly separated and formed the hole-extraction layer. The authors report that this avoided kinetic trapping, a situation in which molecules become stuck in an uneven arrangement before the desired structure forms.
Using a halogen-free toluene process, small-area devices reached a champion power conversion efficiency of 18.7%. Ambient blade coating produced an 18.20-square-centimeter module with a certified efficiency of 16.1%, reported as the highest value to date for a large-area organic photovoltaic module using a self-assembled molecular interfacial layer.
Why larger modules matter
Uniform interfacial layers are important for making solution-processed organic solar cells over larger areas. The reported coating strategy addresses uneven coverage and was compatible with ambient blade coating, a process suited to depositing materials across surfaces rather than making only small laboratory devices.
The 16.1% certified efficiency on an 18.20-square-centimeter module shows that the approach can retain substantial performance beyond small-area devices. The abstract presents the method as a protocol for more uniform, scalable deposition, but it does not establish how it would perform in long-term manufacturing or operation.
Evidence and caveats
The evidence comes from experiments on small-area organic solar devices and an 18.20-square-centimeter module. The module efficiency was certified, while the abstract does not identify the certifying body or provide detailed information about the testing conditions.
The abstract reports the result as the highest value to date for this design, but it does not give a comparison table or describe independent replication. It also does not report long-term stability, performance at larger module areas, manufacturing yield or the effect of extended outdoor operation.
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