Aggregation-induced phosphorescence emission (AIPE) behaviors in Pt-II(C boolean AND N)(N-donor ligand)Cl-type complexes through restrained D-2d deformation of the coordinating skeleton and their optoelectronic properties

摘要

A series of four-coordinated Pt-II(C<^>N)(N-donor ligand)Cl-type complexes have been synthesized through combination between C<^>N-type and N-donor ligands with different sizes. Photophysical features, electrochemical behaviors and electroluminescent (EL) performances have been investigated in detail. Critically, the relationship between the size of organic ligands and aggregation-induced phosphorescence emission (AIPE) behaviors for these Pt-II(C<^>N)(N-donor ligand)Cl-type complexes has been characterized. With extending the dimensions of the C<^>N-type and/or N-donor ligands, the AIPE of these Pt-II(C<^>N)(N-donor ligand)Cl-type complexes is more likely to show up with lower H2O volumetric fractions (f(w)) in the THF solution of these complexes. These unique AIPE experimental results have clearly revealed a new AIE mechanism called restrained D-2d deformation of the coordinating skeleton of these Pt-II(C<^>N)(N-donor ligand)Cl-type complexes from square-planar (D-4h) in the ground states to the tetrahedron (T-d) skeleton in the excited states. In addition, solution-processed organic light-emitting diodes (OLEDs) based on these AIPE emitters have been fabricated to characterize their EL potential. Impressive EL efficiencies with the maximum external quantum efficiency (eta(ext)) of 25.2%, current efficiency (eta(L)) of 53.9 cd A(-1) and power efficiency (eta(P)) of 43.5 lm W-1 can be achieved, indicating great potential of these Pt-II(C<^>N)(N-donor ligand)Cl-type AIPE emitters in the field of OLEDs. Importantly, this research has proposed a new AIE mechanism to promote the development of new phosphorescent AIPE complexes with great potential in the field of OLEDs.