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

ABSTRACT: Visible-to-ultraviolet (vis-to-UV) triplet-triplet annihilation based photon upconversion (TTA-UC) is achieved in a non-volatile chromophoric ionic liquid (IL) for the first time. A novel IL is synthesized by combining UV-emitting anion 4-(2-phenyloxazol-5-yl)benzenesulfonate (PPOS) and trihexyltetradecylphosphonium cation (P₆₆₆₁₄). The nanostructured organization of chromophoric anions is demonstrated by synchrotron X-ray and optical measurements. When the IL is doped with a triplet sensitizer tris(2-phenylpyridinato)iridium(III) (Ir(ppy)₃), the visible-to-UV TTA-UC with a relatively low threshold excitation intensity of 61 mW cm^-2 is achieved. This is due to a large triplet diffusion coefficient in the IL (1.4×10^-7 cm² s^-1) as well as a high absorption coefficient 15 cm^-1 and a long PPOS triplet lifetime of 1.55 ms, all implemented in the condensed IL system. This work demonstrates the unique potential of ILs to control chromophore arrangements for desired functions.

SUBMITTER: Hisamitsu S 

PROVIDER: S-EPMC6946949 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature