Synergy in energy transfer between ligand and EuIII ion in molecular Europium complex: a single-component white light emissive luminogens
Promoting from the structural flexibility and easy solution process capability, single component white light emitting pure organo-lanthanide complexes have considered as a promising candidate for solid state lighting. Here in we report a series of ancillary ligand by using imidazo-bipyridyl derivatives and dibenzoylmethane (DBM), as anionic ligand are employed to synthesized ternary Eu(III) complex Eu(DBM)3L-mCF3, Eu(DBM)3L-pCF3, Eu(DBM)3L-pCH3, Eu(DBM)3L-Naph-OCH3. The photophysical and electrochemical properties of the ligand and their Eu(III) complexes were carefully investigated and the energy transfer mechanism were understood by combined experimental and theoretical calculation. Multiple-emission from both ligand and Eu(III)-ion leads to single component white light emission. White LED was fabricated by conjugating the Eu-complex with near UV LED, the results showed superior performance (CIE (x = 0.33, y = 0.33, close to NTSC standard for pure white emission), CCT (5386K) and CRI (63%)). The selected Eu-complex was further coated on blue LED chip and the corresponding white LED showed CIE (x = 0.36, y = 0.35), CCT (4234K) and CRI (75%). In addition, taking benefit of dual characteristic emission of the Eu-complexes, the ratiometric sensing behavior was explored. The Eu(DBM)3L-mCF3 have the relative sensitivity value of 4.9% K-1 at 323 K.