Intersystem crossing processes in the 2CzPN emitter: a DFT/MRCI study including vibrational spin–orbit interactions

Abstract

Multireference quantum chemical calculations were performed in order to investigate the (reverse) intersystem crossing ((R)ISC) mechanisms of 4,5-di(9H-carbazol-9-yl)-phthalonitrile (2CzPN).

Vibronic effects accelerate the intersystem crossing processes of the through-space charge transfer states in the triptycene bridged acridine–triazine donor–acceptor molecule TpAT-tFFO

“…The chosen computational protocol has proven to yield energies and rate constants that are sufficiently accurate to provide valuable insights into the kinetics of competitive radiative and nonradiative decay processes. [13][14][15][16][17] 2 Computational methods Electronic ground-state geometries of the TpAT-tFFO emitter were optimized using the Turbomole program package 18 and DFT at the PBE0-D3(BJ)/def2-SV(P) level of theory 19,20 including Grimme's dispersion correction (D3) together with Becke and Johnson (BJ) damping. 21,22 Time-dependent DFT (TDDFT) was used for the optimization of the excited singlet states [23][24][25][26] while the Tamm-Dancoff approximation (TDA) was utilized for the optimization of the excited triplet states.…”

“…Fragmentbased analyses of the singlet and triplet DFT/MRCI wavefunctions were performed by an extended version of the Theo-DORE tool box. 17,35 Mutual spin-orbit coupling matrix elements (SOCMEs) between target singlet and triplet states were calculated with the spin-orbit coupling kit (SPOCK) developed in our group. [36][37][38] Here, the SOC is described by using the Breit-Pauli Hamiltonian and the atomic spin-orbit mean-eld approximation.…”

“…Phase corrections were applied as described in earlier work. 17 To check whether vibronic effects accelerate uorescence as well, electric dipole transition moments and their numerical derivatives were employed to compute uorescence in FC and HT approximation. Because the HT spectra are not properly normalized in the VIBES program, we made use of the closure relation for FC factors to normalize the HT spectrum and to determine uorescence rate constants according to…”

“…The chosen computational protocol has proven to yield energies and rate constants that are sufficiently accurate to provide valuable insights into the kinetics of competitive radiative and nonradiative decay processes. 13–17…”

Thermally Activated Delayed Fluorescence of a Pyromellitic Diimide Derivative in the Film Environment Investigated by Combined QM/MM and MS-CASPT2 Methods

“…In such way, spatial overlap of HOMO and LUMO is reduced to a certain extent. Moreover, recent works also proposed that high-order electron correlation plays an important role in minimizing the energy gap of singlet and triplet states. − It is known to us that quantum chemical calculation is a reliable way to explore excited states properties, to reveal their microscopic mechanisms, and to provide solid basis from theoretical perspectives for rational design and synthesis of new luminescent materials. − At present, DFT and TD-DFT methods have been widely used in computational studies of TADF materials. − Recently, Marian and co-workers also studied photophysical properties of TADF materials by combined DFT/MRCI methods. , …”