Effect of Electron and Hole Injection on Spin Polarization in Bis-(8-hydroxyquinoline) Zinc Molecule

The spintronic properties of molecules are essential for the development of multifunctional organic spintronic devices. Here, the spin polarization of bis-(8-hydroxyquinoline) zinc (Znq2) molecule upon electron and hole injection has been theoretically studied by using density-functional theory calculations. It is found that both the injected excess electrons and holes are highly spin polarized in Znq2, leading to an approximately linearly increased magnetic moments with the amount of the charge injected. Our calculation also reveals that the spin polarization upon excess electron and hole injection may attribute to the exchange splitting of lowest unoccupied molecular orbital (LUMO)-related p states of N and C atoms of pyridyl rings and the highest occupied molecular orbital (HOMO)-related p states of O and C atoms of the phenoxide rings, respectively. The d0 ferromagnetism in the charge-injected Znq2 molecule is quite promising for organic spintronic devices.