Interview with the 2025 NIMS Award Laureates
Since 2007, NIMS has presented the international NIMS Award to researchers who have made outstanding contributions to science and technology in the field of materials.
In 2025, the focus is on Environmental & Energy Materials, under the theme “Energy-Related Materials for a Sustainable Society.” The laureates opened up the new field of “perovskite solar cells” and advanced it toward real-world application. Ahead of the award ceremony and special lectures to be held on Tuesday, November 11 at the Tsukuba International Congress Center, we are pleased to share interviews that spotlight their motivations and research journeys.
Prof. Tsutomu Miyasaka
Toin University of Yokohama Faculty of Biomedical Engineering
Prof. Henry J. Snaith
University of Oxford Department of Physics
Prof. Nam-Gyu Park
Sungkyunkwan University School of Chemical Engineering
Impact on Academia and Industry
At the R&D level, perovskite solar cells have achieved power-conversion efficiencies on par with today’s most widespread technology, silicon photovoltaics. Worldwide, efforts are accelerating to scale up module size and improve long-term reliability. Whereas manufacturing the crystalline silicon used in silicon solar cells requires furnace temperatures around 1,400 °C, perovskite devices can be fabricated via low-temperature processing near 100 °C, enabling production on plastic and other flexible substrates. The perovskite layer is a thin film only a few hundred nanometers (nm) thick; when combined with highly flexible transparent electrode materials, it yields solar cells that are lightweight and flexible, offering clear practical advantages.
To harvest sunlight even more efficiently, vigorous development is underway on tandem architectures that pair perovskite as the top cell with crystalline silicon or CIGS (copper indium gallium selenide) as the bottom cell. In Japan, a wide range of companies—from major chemical manufacturers to startups—are actively advancing R&D. Alongside showcase demonstrations for Expo 2025 Osaka, Kansai, Japan, the technology’s lightweight, flexible nature is enabling installations in locations that were difficult for conventional silicon, and pilot deployments and trial sales are already underway.
Hear directly from the laureates and gain a panoramic view of the future of perovskite solar cells.
NIMS Award Symposium 2025 — Tsukuba International Congress Center
Date: Tuesday, November 11, 2025
The Basics of Perovskite Solar Cells
The main functional layers that generate power in a perovskite solar cell are three: the light-absorbing layer, the electron-transport layer (ETL), and the hole-transport layer (HTL). The perovskite crystal acts as the light-absorbing layer; an n-type semiconductor (e.g., TiO₂) serves as the ETL; and a p-type semiconductor (e.g., Spiro-MeOTAD) serves as the HTL.
Here is how electricity is produced. When the perovskite crystal absorbs sunlight, electrons and holes are generated. The electrons are transferred to the ETL and, as they travel through the external circuit to the counter electrode, their energy is harvested as electrical power. Meanwhile, the perovskite crystal that lost electrons is replenished via the HTL, returning to its initial state. Repeating these processes enables continuous power generation. The sun-facing surface is covered with a transparent conducting electrode that transmits light while carrying current.
Prof. Tsutomu Miyasaka
Toin University of Yokohama Faculty of Biomedical Engineering
Research Summary
Prof. Miyasaka is the inventor of the perovskite solar cell, having been the first to apply a perovskite semiconductor—with a large absorption coefficient*1 in the visible region—to photovoltaics. Together with then-graduate student Akihiro Kojima, he was first to demonstrate that perovskite crystals can convert light energy into electrical energy. Building on his prior work in dye-sensitized solar cells*2, he conceived a device that used the perovskite methylammonium lead iodide (CH₃NH₃PbI₃) as the light-absorbing layer, and in June 2009 reported a power-conversion efficiency of 3.8%. That paper has since been cited over 20,000 times.
Today, Prof. Miyasaka collaborates with numerous research institutes and companies to improve efficiency and scale up module size, and he actively leads field demonstrations across Japan—continuing to drive the development of perovskite photovoltaics.
*1 Absorption coefficient: a measure of how efficiently a material absorbs visible light in a solar cell; the higher the value, the more light can be absorbed even by a thin layer.
*2 Dye-sensitized solar cell (DSSC): a photoelectric conversion device that exploits a broad wavelength range by loading molecular dyes—whose absorption bands are tuned by molecular design—onto the surface of an n-type semiconductor (e.g., TiO₂) that readily absorbs ultraviolet light, with the dyes serving as the light-absorbing layer.
― How do you feel about receiving the award?
I’m delighted to see more than twenty years of fundamental research recognized.
― You progressed rapidly on perovskite cell efficiency—from 0.2–0.4% confirmed in 2008, to 3.8% in 2009, and 10.9% in 2012. When did you become most convinced of the technology’s potential?
After we reached 10.9% in 2012, I clearly saw its future potential. We then filed patents via my startup, PECCELL Technologies, Inc. That said, I still had reservations about industrial viability at the time because of stability concerns. Once efficiencies approached 20%, the industrial prospects became much clearer.
― To scale up this Japan-born technology, what strengths does Japan have, and how should they be leveraged?
Japan—especially its small and mid-sized companies—has world-class expertise in precision machining and solution-coating control. To turn that into a competitive advantage, we need to move beyond lab-scale R&D and develop manufacturing technologies on production equipment operated by industry.
― Looking ahead to further performance gains and to issues such as lead-free devices, what is your outlook and what recommendations would you offer?
From an academic standpoint, pushing efficiency higher still has value, but for industrial deployment it is no longer essential. What’s more urgent is sustained materials development to ensure practical durability.
As for lead: although it is environmentally harmful, it is inexpensive, domestically available, and—compared with some highly toxic metals—less toxic. I would therefore like to see an industrial infrastructure that enables 100% recovery, allowing broad societal adoption. That said, for consumer electronics that are easily discarded in daily life (watches, small sensors, etc.), lead-free devices are necessary, and we are advancing perovskites specifically for that purpose.