Spin Polarization Properties of Na Doped Meridianal Tris(8-Hydroxyquinoline) Aluminum Studied by First Principles Calculations

We theoretically investigate the electronic structure and spin polarization properties of Na-doped meridianal tris(8-hydroxyquinoline) aluminum (Alq₃) by first principles calculations. It is found that the spin density is distributed mainly in the Alq₃ part in the Alq₃:Na complex. Electron charge transfer takes place from the Na atom to the Alq₃ molecule, which induces asymmetric changing of the molecule bond lengths, thus the spin density distribution becomes asymmetric. Spin polarization of the complex originates from the preferable filling of the spin-split nitrogen and carbon p-orbitals because of the different bond length changes of the Alq₃ molecule upon Na doping.