Redirecting Light, Rewriting Efficiency: An Interview with Romain Carron

Romain Carron, Group Leader in the Laboratory for Thin Films and Photovoltaics at Empa and leader of Work Package 3, shares how novel solar cell architectures—ranging from bifacial to colour-neutral designs—are shaping the future of thin-film photovoltaics. Discover how advanced light management and material innovation are key to increasing power output while reducing material use and production costs.

As part of our ongoing interview series with Hi-BITS Work Package Leaders, we spoke with Dr Romain Carron, who leads Work Package 3 (WP3) on high-performance solar cells with bifaciality and advanced light management. WP3 plays a critical role in the project’s mission to develop next-generation thin-film solar technologies.

Can you tell us more about the work carried out in WP3?

“Work Package 3 aims to demonstrate high-performance solar cells that produce more power and enable new applications,” Romain explains. “We integrate building block innovations developed in WP2 into three novel architectures. First, bifacial cells convert additional light reflected by the environment into electricity. Second, advanced light management strategies improve how well the solar cells absorb sunlight. And third, we develop colour-neutral ‘see-through’ solar cells for integration into windows.”

These advanced devices will later be scaled up in Work Packages 4 and 5, where mini-module demonstrators will be fabricated and tested under real-world conditions.

What technologies are you developing to enhance light absorption?

“To meet our objectives, we’re adapting fabrication processes to accommodate advanced light management and charge-selective contact passivation,” he notes. “This includes speeding up absorber layer deposition, preventing unwanted interlayer formation, and exploring rear contact passivation by engineering band alignment and introducing point contact schemes.”

Another key innovation involves reducing optical losses. “By modifying materials, compositions, and thicknesses, we aim to minimise reflection and parasitic absorption at both the front and rear of the device.”

Romain also highlights the role of nanostructures. “We’re incorporating light-scattering textures that redirect light horizontally within the device. This allows us to thin the absorber layers to below one micrometre, reducing material use and production costs.”

What role will bifaciality play in the future of solar energy?

“Bifacial modules generate more energy from the same footprint,” Romain says. “They’re especially valuable in ground-mounted solar parks, agrivoltaics, and some building-integrated systems.”

He brings attention to the Swiss context: “In the Alps, several projects aim to install vertically mounted bifacial PV. Thanks to snow reflection, low temperatures, and intense alpine light, these installations can yield twice as much electricity as urban systems during winter—a season of high electricity demand.”

The developments within WP3 are laying the technical foundation for the next steps in Hi-BITS: transferring these high-performance, bifacial, and semi-transparent solar cell concepts into scalable mini-modules. As the project advances, this work will be instrumental in bridging the gap between lab-scale innovation and real-world application—ensuring the novel device architectures envisioned by Hi-BITS can deliver meaningful impact across sectors and climates.

Revisit the video interview: