  Magnetic resonance methods offer a unique chance for in-depth study of
conductive organic material systems, not only accounts for number of charge
carriers, but also allows manipulations of spin dynamics of particles. Here we
present a study of continuous-wave electrically detected magnetic resonance on
a range of organic conjugate polymers under transistor architecture, with
tunability in both carrier concentration and drifting electric field. We
demonstrate the general existence of bipolaron between mobile and trapped
charges at the magnetic resonance condition, then estimates the wavefunction
expansion of charge carriers on their hopping sites along conductive pathways.
This finding allows direct observation of energetically disordered trap sites
under the charge hopping picture, linking-up the microscopic structural
properties to the bulk electronic performances.
