ABSTRACT
Recently, spintronics has expanded its choice of materials to the organic semiconductors (OSCs) [1–3]. OSCs offer unique properties toward their integration with spintronics, the main one being the weakness of the spin-scattering mechanisms in OSC. Spin–orbit coupling is very small in most OSCs; carbon has a low atomic number (Z) and the strength of the spin–orbit interaction (SOI) is in general proportional to Z4 [4]. Typical SOI values in OSC are less than about a few meV [5], well below any other characteristic energy, including main vibrational modes. Small spin–orbit coupling implies that the spin polarization of the carriers could be maintained for a very long time. Indeed, spin relaxation times in excess of 10 µs have been detected by various resonance techniques [6, 7], and these values compare very favorably (at least 103 times larger) with those obtained with high-performing inorganic semiconductors, such as GaAs [8].
