Abstract
In tris(8-hydroxyquinolinato)aluminum (mer-Alq3) position for substitution plays an important role. We explain the push-pull effect on the charge transfer and optical properties, if only one of the ligand among three ligands of meridianal isomer of mer-Alq3 has been substituted. To check this effect, we substituted A-ligand with electron-donating group at position 4 and electron-withdrawing group at position 6. We designed 4-methyl-6-chloro-(8-hydroxyquino)bis(8-hydroxyquinolinato) aluminum (1), 4-methyl-6-cyano-(8-hydroxyquino) bis(8-hydroxyquinolinato) aluminum (2), 4-amino-6-chloro-(8-hydroxyquino) bis(8-hydroxyquinolinato) aluminum (3), and 4-amino-6-cyano-(8-hydroxyquino) bis(8-hydroxyquinolinato) aluminum (4) derivatives of mer-Alq3. All the studied derivatives in the ground (S-0) and first excited (S-1) states have been optimized at the B3LYP/6-31G* and CIS/6-31G* level of theory, respectively. We have designed green light-emitting materials like mer-Alq3 and blue light-emitting materials. These derivatives are good candidates for comparable/better charge carrier mobility as mer-Alq3.