Aggregation-induced phosphorescence emission (AIPE) behaviors in PtII(C∧N)(N-donor ligand)Cl-type complexes through restrained D2d deformation of the coordinating skeleton and their optoelectronic properties

A series of four-coordinated Pt-II(C boolean AND N)(N-donor ligand)Cl-type complexes have been synthesized through combination between C boolean AND 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 boolean AND N)(N-donor ligand)Cl-type complexes has been characterized. With extending the dimensions of the C boolean AND N-type and/or N-donor ligands, the AIPE of these Pt-II(C boolean AND 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 boolean AND 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 boolean AND 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.

Automated summary

A series of four-coordinated Pt-II(C and N)(N-donor ligand)Cl-type complexes have been synthesized and characterized, revealing a new AIE mechanism related to the size of organic ligands and aggregation-induced phosphorescence emission. These complexes show AIPE behavior in THF solutions with lower H2O volumetric fractions, and exhibit promising potential in OLED applications with impressive EL efficiencies. This research proposes the development of new phosphorescent AIPE complexes with high potential in the field of OLEDs.