Theoretical Design of Electrons Transporting for Application in OLEDs.

Abstract

This paper presents the design of new materials to be used like electron transport in OLEDs based on ALQ₃ structure. The modifications in the precursor structure were done aim to increase the LUMO energy. From this idea electron donors and acceptor groups were chosen to modify the structure of the ALQ₃ precursor molecule. Two different crystallographic structures of ALQ₃ were obtained from literature. Both structures had their optimized geometry with the B3LYP/6-31G**, AM1, PM3, PM6 and PM7 methods. Then, the optimized structures were compared with the crystallographic data. The results indicated that the B3LYP/6-31G ** and PM7 methods have similar accuracy. Based on this, as it would need to study 16 different modified structures, we decided to choose the semiempirical PM7 method due to its greater computational efficiency compared to B3LYP/6-31G** method. Thus, all 16 structures were optimized with the PM7 and their LUMO energies obtained from 1SCF B3LYP/6-31G** calculation of the PM7 optimized geometries. The results showed that the increase in LUMO energy was provided by adding electron-donor groups. Moreover the LUMO energy may be higher with the addition of donor stronger. It was also possible to verify the accuracy of the method PM7, compared to its predecessors.