Recent progress in organic spintronics is given an informative overview, covering spin injection, detection, and trans-port in organic spin valve devices, and the magnetic field effect in organic semiconductors （OSCs）. In particular, we focus on our own recent work in spin injection and the organic magnetic field effect （OMFE）.
For the organic magnetoresistance （OMAR） effect, we suggest a spin-related hopping of carriers （polarons） based on Marcus theory. The mobility of polarons is calculated with the master equation （ME） and then the magnetoresistance （MR） is obtained. The theoretical results are consistent with the experimental observation. Especially, the sign inversion of the MR under different driving bias voltages found in the experiment is predicted. Besides, the effects of molecule disorder, hyperfine interaction （HFI）, polaron localization, and temperature on the MR are investigated.
