Predicting Phosphorescence Quantum Yield for Pt(II)-Based OLED Emitters from Correlation Function Approach

Abstract

We report a new formulation for Golden Rule-based predictions of photoluminescence quantum yields (PLQY) of phosphorescent emitters containing a heavy element, and its implementation compatible with first-principles computation frameworks. The main components of PLQY (i.e., phosphorescent rate and intersystem crossing rate from the lowest triplet state to the ground singlet state) are obtained through correlation functions in time domain, and the relativistic effects are also considered using the relativistic effective core potentials. The spin–orbit coupling is treated in a perturbative manner to generate spin–orbit-corrected, two-component T1 substates within single-excitation theory, where the electronic transition dipole moments and the non-Born–Oppenheimer coupling matrix elements to the S0 state are computed. We applied this new approach to the photophysical properties of 34 Pt(II) complexes designed for the organic light-emitting diode (OLED) applications and observed a good agreement between predictions and experiments over diverse scaffolds. For the two representative complexes, further analysis on the nonradiative characteristics was performed based on the decomposition of the non-Born–Oppenheimer coupling into contributions from the nuclear vibrations and from the excited-state electronic structures.