Injection, Transport, Absorption and Phosphorescence Properties of a Series of Platinum (II) Complexes with N-heterocyclic Carbenes: a DFT and Time-dependent DFT Study

The ground and excited states, charge injection/transport, and phosphorescence properties of five N‑heterocyclic carbine-functionalized Pt(II) complexes were investigated by using the DFT method. By analyzing the nonradiative (k nr) rate constant and energies at [Formula: see text] and [Formula: see text] states, it is possible to forecast that BC5 with the pyrrole ligand has a higher phosphorescence quantum yield than any of the other four complexes. Thus, we consider that BC5 will be an efficient phosphorescent material that has balanced electron/hole-transport performance as well as high phosphorescence quantum yield. The calculated results indicate that, for the studied complexes, the nature of the ligand strongly affected the energy of the emissive state and was able to tune the emission color. We hope that our study will aid better understanding of the structure-property relationship of phosphorescent Pt (II) complexes and provide constructive information for designing novel and highly efficient OLED materials in the future.