Abstract
We studied on the effect of nanoparticle dispersion on electrical properties of polymer field effect transistor (FET). Various kinds of powder materials were prepared and dispersed into P3HT films. In order to determine the electronic structures of particle-dispersed P3HT films, photoelectron emission spectra were measured. Using these spectra ionization potentials (I<sub>P</sub>s) of these films were determined. The shifts of IP originated from the particle dispersions were very small (from 4.69 to 4.72eV). Similarly, any differences were not observed between the electron absorption spectra of the particle-dispersed P3HT films and that of the pristine P3HT films. According to these results, no chemical reactions would occur between P3HT matrices and dispersed particles. On the other hand, Fermi levels of particle-dispersed P3HT films were obviously shifted from that of the pristine P3HT film. The shift was well correlated to the difference between the workfunction of P3HT and that of the dispersed material. Namely, the dispersion of the particles with the lower workfunction contributed to the decrease of workfunction of the P3HT film. Further, the decrease of workfunction of P3HT film resulted in the decrease of the off-current values of the P3HT-FET. This would be because the electrons transferred from the dispersed particles neutralized the excess holes in the P3HT film. Actually, the Ag particle dispersion remarkably improved on-off ratio of the P3HT-FET.
Published Version
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