TY - JOUR
T1 - Diabatic Decomposition Perspective on the Role of Charge Transfer and Local Excitations in Thermally Activated Delayed Fluorescence
AU - de Sousa, Leonardo Evaristo
AU - de Silva, Piotr
PY - 2022
Y1 - 2022
N2 - Thermally activated delayed fluorescence (TADF) is a phenomenon that relies on the upconversion of triplet excitons to singlet excitons by means of reverse intersystem crossing (rISC). It has been shown both experimentally and theoretically that the TADF mechanism depends on the interplay between charge transfer and local excitations. However, the difference between the diabatic and adiabatic character of the involved excited states is rarely discussed in the literature. Here we develop a diabatization procedure to implement a four-state model Hamiltonian to a set of TADF molecules. We provide physical interpretations of the Hamiltonian elements and show their dependence on the electronic state of the equilibrium geometry. We also demonstrate how vibrations affect the TADF efficiency by modifying the diabatic decomposition of the molecule. Finally, we provide a simple model that connects the diabatic Hamiltonian to the electronic properties relevant to TADF and show how this relationship translates into different optimization strategies for rISC, fluorescence, and overall TADF performance.
AB - Thermally activated delayed fluorescence (TADF) is a phenomenon that relies on the upconversion of triplet excitons to singlet excitons by means of reverse intersystem crossing (rISC). It has been shown both experimentally and theoretically that the TADF mechanism depends on the interplay between charge transfer and local excitations. However, the difference between the diabatic and adiabatic character of the involved excited states is rarely discussed in the literature. Here we develop a diabatization procedure to implement a four-state model Hamiltonian to a set of TADF molecules. We provide physical interpretations of the Hamiltonian elements and show their dependence on the electronic state of the equilibrium geometry. We also demonstrate how vibrations affect the TADF efficiency by modifying the diabatic decomposition of the molecule. Finally, we provide a simple model that connects the diabatic Hamiltonian to the electronic properties relevant to TADF and show how this relationship translates into different optimization strategies for rISC, fluorescence, and overall TADF performance.
U2 - 10.1021/acs.jctc.2c00310
DO - 10.1021/acs.jctc.2c00310
M3 - Journal article
C2 - 36007256
SN - 1549-9618
VL - 18
SP - 5459
EP - 5470
JO - Journal of Chemical Theory and Computation
JF - Journal of Chemical Theory and Computation
IS - 9
ER -