Researchers have developed a groundbreaking solid-state material that converts visible light into ultraviolet (UV) light, potentially unlocking new ways to harness solar energy. Because UV light carries more energy than visible light, it plays a critical role in applications such as artificial photosynthesis, photocatalysis, hydrogen production, and sterilization.
However, UV light accounts for only about 4% of the sunlight that reaches Earth’s surface. As a result, scientists have long searched for ways to transform the abundant visible portion of sunlight into higher-energy UV radiation.
Overcoming Long-Standing Challenges
To address this challenge, a team from Tokyo Institute of Technology created a solid material capable of “upconverting” low-energy visible light photons into high-energy UV photons. The process, known as photon upconversion, allows the material to generate UV light from sunlight-intensity visible light.
Previous upconversion systems typically relied on liquid solutions that required oxygen-free environments and airtight containers. Moreover, these materials often degraded quickly when exposed to air and performed poorly under natural sunlight conditions.
In contrast, the newly developed solid film remains stable in air while efficiently converting visible light into UV light. This breakthrough significantly improves the practicality of photon upconversion technology.
Record-Breaking Stability and Efficiency
The research team demonstrated that the material maintains its performance for more than 100 hours in air, setting a new benchmark for photostability in this class of materials. Additionally, the film operates under light intensities lower than natural sunlight and achieves impressive conversion efficiency.
As reported by Interesting Engineering, the material combines an ultralow excitation threshold with a high upconversion quantum yield, enabling it to function effectively even under weak visible-light conditions.
Innovative Manufacturing Process
The researchers created the film by melting together two key components—a sensitizer, which absorbs visible light, and an annihilator, which facilitates the energy-transfer process. They then cooled the mixture using a temperature-gradient-controlled technique to form a solid thin film.
Importantly, this manufacturing method offers high reproducibility and compatibility with industrial-scale production. Consequently, the technology could move more easily from the laboratory to real-world applications.
Demonstrating Real-World Applications
To validate the material’s capabilities, the team exposed the film to simulated sunlight containing only visible light. The generated UV light successfully cured and solidified a resin that would normally require direct UV exposure.
This demonstration highlights the material’s potential in industries that depend on UV-driven chemical reactions. Furthermore, it could enhance technologies used in environmental purification, green hydrogen production, and advanced manufacturing.
A Step Toward More Efficient Solar Energy Use
The development marks an important advance in solar-energy utilization. By transforming abundant visible light into useful UV radiation, the material broadens the range of reactions and processes that sunlight can power.
Looking ahead, researchers believe the technology could support a new generation of UV-light-generating materials and help industries make better use of low-intensity sunlight and indoor lighting. As a result, the innovation may contribute to cleaner energy systems and more sustainable industrial processes.
