Two new AIE-active dinuclear Schiff base Ir(III) complexes exhibit highly reversible piezochromic phosphorescence behaviour enabling the construction of a re-writable phosphorescence data recording device.
The geometries, electronic structures, photophysical properties and spin-orbit coupling (SOC) effects in the radiative process for the recently synthesized complexes (Bppy)Pt(acac) (1) and (BNppy)Pt(acac) (2) as well as the designed complexes 3-6 were investigated by DFT and TD-DFT calculations, to reveal the influences of the functional ligands on charge injection ability and phosphorescence efficiency of emitters. It is found that compared with electron acceptor complex 1, complexes 2-6 have lower ionization potentials and comparable high electronic affinities, which are suited for bipolar luminescent materials. The results also demonstrated that Bppy complexes 1, 5 and 6 have more (3)MLCT compositions in T1 emitting states compared with BNppy complexes 2-4, which results in strong SOC and fast kr. Thus, the phosphorescence efficiency of 1 is higher than that of 2. In addition, 5 and 6 have the balanced charge transport and better hole injection ability when the hole-transporting ligand is incorporated to 1. Therefore, 5 and 6 can server as promising candidates for efficient multifunctional phosphorescent OLED emitters owing to their ambipolar characters, balanced charge carrier injection/transport features and high phosphorescence quantum efficiency.
Two reported Ir(iii) complexes 1a and 1b containing oxazoline and imidazoline in ancillary ligand, respectively, were investigated by DFT/TD-DFT method. In order to obtain full-color display materials, we designed a group of Ir(iii) complexes 2a-3d based on 1a, which exhibits higher quantum efficiency in phosphorescence, by introducing electron-donating/electron-withdrawing moieties to different positions of the ancillary ligand to adjust emission color. In addition to calculating the radiation rate and analyzing its determining factors, we also estimated nonradiative ability by evaluating the spin-orbit coupling matrix element between the ground state (S) and the lowest triplet state (T) as well as the reorganization energy from T to S to estimate quantum efficiency more accurately. In particular, an in-depth analysis on the contribution of each vibration mode to reorganization energy helped us to identify the effect of substituents on the nonradiative process. Besides, charge injection/transfer properties and energy relation of the states related to exciton quenching via the triplet metal-centered state were also examined, which provide an estimation on the OLED performance of our designed complexes. Overall, we expect 2b and 3c to be more efficient blue-emitting emitters than 1a and 3a and 3b to be efficient green and red emitters, respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.