Kyushu University Builds 1.9% Sunlight-to-UV Solid as Daylight Clears Key 1.2 mW/cm2 Threshold
Updated
Updated · ScienceBlog.com · Jun 23
Kyushu University Builds 1.9% Sunlight-to-UV Solid as Daylight Clears Key 1.2 mW/cm2 Threshold
3 articles · Updated · ScienceBlog.com · Jun 23
Summary
Kyushu University researchers reported a solid film that turns ordinary visible sunlight into ultraviolet light at 1.9% efficiency, marking a rare daylight-driven upconversion result in a stable solid.
The film works because DHI molecules use built-in alkyl spacers to keep neighboring pi-electron clouds apart, preserving triplet energy long enough for triplet-triplet annihilation to generate UV photons.
The best isobutyl variant delivered more than 60% solid-state fluorescence yield—reaching 83% in some measurements—versus about 10% for the unmodified molecule, while operating in open air despite oxygen exposure.
A 1.2 mW/cm2 activation threshold puts the process just below relevant natural sunlight intensity, avoiding lasers or concentrating optics that most solid-state rivals still require.
The team has filed a patent and is targeting solar photocatalysis, indoor air purification and low-power 3D printing, though batch variability from simple coating methods still limits performance.
Scientists spent 14 years creating this light-converting material. What is the next major barrier to widespread adoption?
A new film turns sunlight directly into germ-killing UV rays. Could this solve the world's clean water crisis?
Record 1.9% Efficiency in Solid-State Visible-to-UV Upconversion: Kyushu University’s Game-Changing Solar Innovation
Overview
Researchers at Kyushu University, led by Professor Nobuo Kimizuka, have developed a novel solid-state material that can convert ordinary visible sunlight into ultraviolet light with a record efficiency of 1.9 percent. This breakthrough operates under everyday conditions without the need for high-intensity lasers or special optics, marking a major advance in photon upconversion technology. The achievement is the result of extensive long-term research and stands out because most other materials struggle to work at low light levels or require complex equipment. This innovation opens new possibilities for sustainable and practical applications using sunlight.