There are numerous research works that have contributed towards our current understanding of F 4 TCNQ doped P3HT system prepared using different methods. In the solution co-processing method, F 4 TCNQ is mixed with P3HT in a low-dielectric solvent like chorobenzene, which is spin-casted over the desired substrate to form oriented doped films. To gain structural insight of the spin-casted polymer films, various experimental tools have been used e.g. atomic force microscopy (AFM), grazing incidence wide-angle Xray scattering (GIWAXS), electron paramagnetic resonance spectroscopy, 18 infrared spectroscopy, Raman spectroscopy, electron diffraction etc. An early hypothesis was that the F 4 TCNQ anion stacks between the ordered polymer chains via π-π interactions.