Computational Protocol to Calculate the Phosphorescence Energy of Pt(II) Complexes: Is the Lowest Triplet Excited State Always Involved in Emission? A Comprehensive Benchmark Study

Abstract

The reliable calculation of the phosphorescence energies of phosphor materials is at the core of designing efficient phosphorescent organic light-emitting diodes (PhOLEDs). Therefore, it is of paramount importance to have a robust computational protocol to perform those calculations in a black-box manner. In this work, we use Domain Based Local Pair Natural Orbital Coupled Cluster theory with single, double and perturbative triple excitation (DLPNO-CCSD(T)) calculations to attain the phosphorescence energies of a large pool of Pt (II) complexes. Several approaches to incorporate relativistic effects in our calculations were tested. In addition, we have used the DLPNO-CCSD(T) values (i.e., our best theoretical values) to assess the performance of different flavors of density functional theory including pure, hybrid, meta-hybrid, and range-separated functionals. Among the tested functionals, the M06HF functional provides the best values as compared with the DLPNO-CCSD(T) ones, with a mean absolute deviation (MAD) value of 0.14 eV. In its turn, and thanks to the increased accuracy achieved in the calculation of phosphorescence energies, we also demonstrate that not all the investigated complexes emit from their lowest lying triplet-state (T 1 ). The outlier complexes include different complex photophysical scenarios and both Kasha and anti-Kasha types of complexes. Finally, we provide a general computational protocol to pre-screen whether T 1 is actually the emissive state and to accurately calculate the phosphorescence energies of Pt (II) complexes. 57 Different xc functionals including pure functionals (BP86 58,59 , B97D 60 ), range-separated hybrid

Light‐Driven Multi‐Charge Separation in a Push‐Pull Ruthenium‐Based Photosensitizer – Assessed by RASSCF and TDDFT Simulations

“…The excited-state properties of 3 Ru were investigated at the TDDFT level of theory by means of the 100 lowest dipole-allowed triplet-triplet excitations. Application of the Tamm-Dancoff approximation (TDA), which often provides an improved energetic description of the low-lying triplet states, [77,78] was not considered as the main focus of the present study was to address the Franck-Condon photophysics of Ru. This is further justified as the energy of the triplet ground state in 3 Ru, i. e. of 3 ILCT character, differs merely by 0.2 eV as obtained by DFT (1.76 eV) vs. TDDFT (1.56 eV), see Figure 5B.…”

Anti-Kasha Fluorescence in Molecular Entities: Central Role of Electron–Vibrational Coupling

“…To be able to use the harmonic approximation for the (forward and backward) internal conversion here, the PESs of S 1 and S 2 need to be nested since otherwise an Arrhenius-type expression needs to be used for the interconversion between the excited states. 31,32 As a representative example of type II compounds, we explore the excited states of [3,4]-benzopyrene (2), which experimentally displays dual fluorescence. 12 In benzopyrenes but also in naphthalene and other acenes, the first two excited states typically correspond to the bright La state (a HOMO → LUMO transition) and the dark Lb state (HOMO → LUMO + 1 and HOMO − 1 → LUMO transitions).…”

“…A Comprehensive Benchmark StudyKumarP.EscuderoD. Kumar, P. Escudero, D. 10.1021/acs.inorgchem.1c025622021601723017240 …”

Theoretical investigation of triplet potential energy surfaces for (C^C*) cyclometalated platinum(ii) complexes and the corresponding control strategies

“…For the monometallic Pt(II) complexes, according to the calculated results of triplet optimizations, two different configurations were achieved, that is, T planar 1 and T bent 1 , respectively, which are consistent with the previous reports. 39,40 The optimized geometries of T 1 states, the corresponding spin densities and adiabatic triplet energies are shown in Fig. 1.…”