The optical properties of nanocomposite MEH-PPV:ZnO thin films

In this paper, the effect of different weight percentage of ZnO nanoparticles on the optical properties of the nanocomposite MEH-PPV:ZnO thin films was studied. The samples were prepared using sol-gel spin coating method on glass substrates. Current-voltage properties of the thin films were investigated. The conductivity of the samples increases with the increment of the ZnO nanoparticles except for sample with 10wt% of the ZnO in the nanocomposite thin films.The optical properties were studied using UV-Vis-NIR spectrometer for transmittance and absorbance of the thin films. The optical transmittance spectra of pure MEH-PPV and nanocomposite MEH-PPV:ZnO thin films in the UV-Visible-NIR wavelength range (200-800 nm) are presented. The highest transmittance was obtained in samples with 10 wt% ZnO, while the lowest transmittance was obtained in pure MEH-PPV samples. The enhancement of optical band gap energy in MEH-PPV thin films with ZnO contribution might due to the increasing of carrier concentration increase the band gap energy. As ZnO concentration is increased, the carrier concentration increased resulting in the optical band gap widening with doping concentration. This is supported by the I-V measurement result, which conductivity varied due to increasing carrier concentration.