Scientists in Japan have developed a breakthrough solid-state material capable of transforming ordinary visible sunlight into higher-energy ultraviolet (UV) light, a discovery that could expand the range of solar-powered technologies in the years ahead.
Researchers at Kyushu University reported that the new material can convert visible light into UV light under natural sunlight conditions, overcoming a challenge that has limited the practical use of photon upconversion technologies for decades.
UV light plays a crucial role in applications such as air purification, photocatalysis, advanced manufacturing, 3D printing, medical materials and industrial curing processes. However, ultraviolet radiation represents only a small fraction of the sunlight reaching Earth’s surface, limiting its direct use in many technologies.
The research relies on a process known as photon upconversion, where the energy from two low-energy light particles is combined to generate a single particle with higher energy. While this phenomenon has previously been demonstrated in liquid systems, achieving it efficiently in solid materials has proven far more difficult.
The breakthrough came through the design of a specialized organic semiconductor called dihydroindenoindenedene (DHI). By carefully controlling the spacing between molecules, the research team enabled efficient energy transfer while avoiding energy losses that typically reduce performance in solid-state materials.
According to the study, the material achieved a visible-to-UV conversion efficiency of 1.9% under sunlight and a fluorescence quantum yield exceeding 60%, figures that represent a significant advance for solid-state photon upconversion technologies.
Researchers believe the innovation could support future developments in solar-driven chemical reactions, indoor air purification systems and low-energy manufacturing processes. The material is also considered attractive for commercial applications because it can be produced using relatively simple synthesis methods and low-cost starting materials.
The discovery marks the culmination of more than a decade of research led by Nobuo Kimizuka and his team, who have worked extensively on molecular self-assembly and photon upconversion systems. The researchers describe the achievement as a major milestone in the field of advanced materials and solar energy conversion.
