Role of Sulfur Oxidation in Controlling Electronic Properties of the Sulfur-Containing Host Molecules for Phosphorescent Organic Light-Emitting Diodes
In this study a series of dibenzothiophene (DBT) derivatives with different valence states of sulfur atoms have been reported as host materials for blue phosphorescent organic light-emitting diodes. Their electronic properties have also been thoroughly investigated to develop structure–property relationships which include consideration of the effect of various oxidation states of sulfur atom in the core moiety and linking (C-N linkage) of subunits with core at different positions. Results obtained from the electronic structure calculations highlight that, the triplet energy (ET), singlet-triplet energy difference (ΔEST), reorganization energy for the hole and the injection barrier for the electron decrease with an increase in the oxidation state of sulfur atom in the DBT. On the other hand, injection barrier for the hole and the reorganization energy for the electron increase upon increasing the oxidation state of sulfur atom present in the DBT.