Department of Chemistry
A versatile color tuning strategy for iridium(III) and platinum(II) electrophosphors by shifting the charge-transfer states with an electron-deficient core
By fusing an electron-deficient ring system with the phenyl ring of a 2-phenylpyridine (ppy)-type ligand, a new and synthetically versatile strategy for the phosphorescence color tuning of cyclometalated iridium(III) and platinum(II) metallophosphors has been established. Two robust red electrophosphors with enhanced electron-injection/electron-transporting features were prepared by using an electron-trapping fluoren-9-one chromophore in the ligand design. The thermal, photophysical, redox and electrophosphorescent properties of these complexes are reported. These exciting results can be attributed to a switch of the metal-to-ligand charge-transfer (MLCT) character of the transition from the pyridyl groups in the traditional IrIII or PtII ppy-type complexes to the electron-deficient ring core, and the spectral assignments corroborate well with the electrochemical data as well as the time-dependent density functional theory (TD-DFT) calculations. The electron-withdrawing character of the fused ring results in much more stable MLCT states, inducing a substantial red-shift of the triplet emission energy from yellow to red for the IrIII complex and even green to red for the PtII counterpart. Electrophosphorescent organic light-emitting devices (OLEDs) doped with these red emitters fabricated by using vacuum evaporation technique have been realized with reasonable performance. © The Royal Society of Chemistry 2009.
Source Publication Title
Journal of Materials Chemistry
Royal Society of Chemistry
Link to Publisher's Edition
Zhou, G., Wang, Q., Wong, W., Ma, D., Wang, L., & Lin, Z. (2009). A versatile color tuning strategy for iridium(III) and platinum(II) electrophosphors by shifting the charge-transfer states with an electron-deficient core. Journal of Materials Chemistry, 19 (13), 1872-1883. https://doi.org/10.1039/B814507E