Overview
- A Kyushu University team published a Nature Communications paper on June 23, 2026 reporting a laboratory solid-state film that upconverts ordinary visible sunlight into ultraviolet light with a measured 1.9 percent visible‑to‑UV efficiency.
- The film is built from a modified organic semiconductor, dihydroindenoindenedene (DHI), whose alkyl side chains create precise gaps between molecules so energy can transfer without quenching.
- The conversion relies on triplet–triplet annihilation: a donor absorbs visible light, transfers triplet energy to an acceptor, and two triplet excitations collide to emit one higher‑energy UV photon.
- In tests the engineered solid showed a solid‑state fluorescence quantum yield above 60 percent, the team has filed a patent, and they name near‑term uses such as solar photocatalysis, indoor air purification, and low‑intensity 3D printing while noting the result is an early-stage demonstration.
- The result caps more than 14 years of work led by Nobuo Kimizuka and colleagues and was completed just before Kimizuka’s retirement, highlighting both a long research arc and remaining needs for stability, scaling, and device integration before commercial use.