Theoretical study on the electronic structure of triphenyl sulfonium salts: Electronic excitation and electron transfer processes

- Differences are found in the electronic structure of triphenyl sulfonium salts involving different counter anions.
- The first excited state of TPS and TPS salts is dissociating.
- Addition of electron to TPS leads to its dissociation.
- Addition of electron to TPS salts leads to stable anions.

Density functional theory (DFT) and Time Dependent DFT calculations on triphenyl sulfonium cation (TPS) and the salts of TPS with triflate, nonaflate, perfluoro-1-octanesulfonate and hexafluoro antimonate anions are presented. These systems are widely used as cationic photoinitiators and as electron ejection layer for polymer light-emitting diodes. While some differences exist in the electronic structure of the different salts, their lowest energy intense absorption maxima are calculated at nearly the same energy for all systems. The first excited state of TPS and of the TPS salts is dissociating. Electron addition to the TPS salts lowers their energy by 1.0-1.33 eV.

DFT and TDDFT calculations on salts of triphenyl sulfonium cation with different counter anions yield their lowest excited state dissociating and stable anionic forms of the salts at similar geometries as the neutral.57