Visible-to-UV Photon Upconversion in Nanostructured Chromophoric Ionic Liquids.

Invited for this month's cover picture is the group of Professor Nobuhiro Yanai and Nobuo Kimizuka at Kyushu University. The cover picture shows visible-to-ultraviolet (vis-to-UV) triplet-triplet annihilation-based photon upconversion (TTA-UC) via triplet exciton diffusion in a chromophoric ionic liquid (IL). Chromophore moieties spontaneously form continuous arrays in non-polar nano-domains of the IL. The close arrangement of the chromophores in the IL allowed effective diffusion of triplet excitons, resulting in the vis-to-UV TTA-UC at a low excitation intensity. Read the full text of their Communication at https://doi.org/10.1002/open.201900304.