Comprehensive Investigation into Luminescent Properties of Ir(III) Complexes: An Integrated Computational Study of Radiative and Nonradiative Decay Processes

Abstract

A comprehensive and concrete exploration into the deactivation mechanisms of luminescent materials is imperative, with the improvement of simulating and computing technology. In this study, an integrated calculation scheme is employed on five Ir(III) complexes for thorough investigation of their photophysical properties, including radiative ( k) and nonradiative ( k) decay rates. As a most famous Ir(III) complex with superior quantum efficiency, fac-Ir(ppy) herein serves as a reference relative to the other four β-diketonate complexes. Both temperature-independent and temperature-dependent k are taken into account quantitatively for the first time, to unearth the role of different ancillary ligands in the determination of luminescent properties. Since the validated calculations of k for the five complexes are of the same order of magnitude, the nonemissive peculiarity of 4 is caused by large k. The newly designed compound 5, which simply has two more -CH groups than 4 in the ancillary ligand, further manifests that the reason for large k in molecule 4 should be attributed to the ligand resonance caused by great π conjugation.

Red‐to‐NIR Iridium(III) Emitters: Synthesis, Photophysical and Computational Study, the Effects of Cyclometallating and β‐Diketonate Ligands

“…The relevant chemistry is very well developed, numerous phosphorescent iridium complexes have been prepared and their photophysics was studied in detail experimentally and theoretically. [1,9,17,23,24,26,27] The complexes containing β-diketonate ligands as L^L chelates are an important part of this family of emitters. [5,[28][29][30][31][32] These type of compounds differ from the other complexes containing neutral chelates (for example, aromatic diimines) by zero complex charge and stronger (covalent/electrostatic) binding to metal center.…”

Analyzing the Relation between Structure and Aggregation Induced Emission (AIE) Properties of Iridium(III) Complexes through Modification of Non‐Chromophoric Ancillary Ligands

“…This photophysical profile strongly contrasts with the Φ PL and Φ PL of fac ‐Ir(dFppy) 3 ( τ PL = 1.64 µs, Φ PL = 77 %) . Indeed, previous DFT calculations for 1 suggested that the emission had MLCT mixed with intraligand charge transfer (ILCT) character and the poor emissive properties in solution were caused by efficient non‐radiative decay promoted by strong vibrations of the dbm in the low frequency region . Therefore, comparable behavior would be expected for complex 3 .…”

Theoretical insight on electronic structure and photophysical properties of a series of cyclometalated iridium(III) complexes bearing the substituted phenylpyrazole with different electron-donating or electron-accepting groups

“…Via variation of the main ligands, the emission colors for complexes Ir1-Ir7 can be adjusted from blue to yellow in CH 2 Cl 2 solutions. It is known that the control of the optical physical process must ensure the structural similarity, so that the expected increase of the radiative decay rate can ensure the improvement of the overall efficiency [22,23]. Hence, on the basis of complex Ir6 [21], we have theoretically designed four complexes and investigated their electronic structure and photophysical properties by density functional theory (DFT) and time-dependent density functional theory (TDDFT) method.…”