Ultrathin Solar Cells Get Efficiency Upgrade Thanks to INL Research
- MM24 Multimedia Desk
- 4 days ago
- 2 min read
Ultrathin solar cells are emerging as a promising avenue for clean energy. Compared to conventional solar technologies, they use significantly less material, can be manufactured more quickly, and can even be applied to flexible or curved surfaces. However, their reduced absorber thickness comes with a trade-off: too thin, and the cells struggle to capture enough light, with energy leaking out the back, limiting their overall efficiency.
A research team at the Idaho National Laboratory (INL), led by Pedro Salomé, in collaboration with institutions including Uppsala University in Sweden, has developed an innovative solution to this challenge: a nanostructured “mirror” that improves light absorption and minimizes energy losses in ultrathin solar cells.
Nanostructured Rear Contact Reflects Light and Reduces Losses
The team created the mirror by embedding an ultra-thin patterned layer of gold, encapsulated with aluminum oxide, at the rear of the solar cell. This design serves a dual purpose: it reflects light back into the absorber layer and reduces energy losses at the back interface. “This works by providing interface passivation,” explains Pedro Salomé, highlighting the role of the architecture in maintaining device efficiency.
What makes this innovation particularly notable is its fabrication method. Using one-step nanoimprint lithography, the researchers avoided the traditionally costly, multi-step nanofabrication processes. According to Salomé, “this paves the way for industrial scale-up,” making the approach more practical for real-world applications.
Efficiency Gains Demonstrated on ACIGS Solar Cells
The new architecture was tested on ultrathin ACIGS solar cells ((Ag,Cu)(In,Ga)Se₂). The results showed a 1.5% absolute improvement in power conversion efficiency, primarily due to enhanced light absorption within the cell. The method proved particularly effective at lower fabrication temperatures (around 450 °C).
Lower temperatures offer multiple advantages: they stabilize the gold-based architecture by preventing diffusion issues that can degrade performance, and they are compatible with flexible substrates, opening the door to lightweight and versatile solar applications. “This approach brings ultrathin, flexible solar cells closer to achieving efficiencies suitable for real-world deployment,” says André Violas, first author and Research Engineer in the Nanofabrications, Optoelectronics, and Energy Applications group.
Combining Light Management and Interface Passivation
The key to this breakthrough lies in combining light management with interface passivation. By reflecting more light back into the absorber while simultaneously reducing recombination losses at the interface, the nanostructured mirror maximizes the performance of ultrathin devices. “This architecture gives us a powerful way to manage light and reduce interface recombination in ultrathin devices while keeping fabrication practical,” Violas adds.
For researcher Jennifer Teixeira, the study represents the culmination of efforts to merge two crucial design principles. “By integrating light management with interface passivation, we are starting to create novel solar cell architectures that could transform flexible and lightweight solar technology,” she says.
Funding and Publication
The research, published in Solar RRL, was conducted under the R2U Technologies project, part of the Portuguese Resilience and Recovery Plan funded through NextGenerationEU, with support from four individual Fundação para a Ciência e Tecnologia (FCT) fellowships.
This advancement marks a significant step toward making ultrathin, flexible, and high-efficiency solar cells viable for commercial and real-world energy applications, promising a future where lightweight and versatile solar technologies can play a major role in sustainable energy generation.
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