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[6p-C11-14] Preparation of P3HT nanoparticles by reprecipitation and the composite films with n type organic semiconductor
Keywords:semiconductive polymer, organic semiconductor, crystallinity
Reprecipitation method, very easy and useful to prepare nanoparticles, can provides monodisperse dispersions of nanoparticles by only injecting dilute solution into a poor solvent under agitation. We prepared nanoparticle dispersions of regioregular poly(3-hexylthiophene) (P3HT) used as a p-type semiconductor with different molecular weight by reprecipitation method. Particle diameters of the nanoparticles were estimated a few tens of nanometers by both of dynamic light scattering measurement and scanning electron microscope observation. UV-vis absorption spectra of the P3HT dispersions were measured. The peak that derived from a lamella crystalline phase of P3HT on the long wavelength region than 520nm in which molecular weight was observed. The peak was more conspicuously observed in P3HT of high molecular weight than that of low molecular weight.From this, It was revealed that the crystallinity of P3HT nanoparticles in dispersion was dependent on the molecular weight. Moreover the crystallinity of cast films prepared from these nanoparticles was also dependent on molecular weight of P3HT.
P-n composite blend films were prepared by drop casting the p-n blend dispersion from P3HT nanoparticles and PCBM. The absorption spectra of the films which changed and prepared the mixture ratio of PCBM and P3HT were measured. The absorption spectra that was similar to the P3HT nanoparticles pristine film were observed in which mixture ratio in the P3HT nanoparticles of high molecular weight. On the other hand, the peak derived from P3HT crystalline phase decreased as volume ratio of PCBM increase in the P3HT nanoparticles of low molecular weight. Therefore the crystallinity of low molecular P3HT nanoparticles decreased by PCBM blend. In other words, crystalline structures of the P3HT nanoparticles of high molecular weight were easily disturbed by PCBM blend than those of high molecular weight. We considered that this is due to low crystallinity of the P3HT nanoparticles of low molecular weight which means there are many soft amorphous parts.
P-n composite blend films were prepared by drop casting the p-n blend dispersion from P3HT nanoparticles and PCBM. The absorption spectra of the films which changed and prepared the mixture ratio of PCBM and P3HT were measured. The absorption spectra that was similar to the P3HT nanoparticles pristine film were observed in which mixture ratio in the P3HT nanoparticles of high molecular weight. On the other hand, the peak derived from P3HT crystalline phase decreased as volume ratio of PCBM increase in the P3HT nanoparticles of low molecular weight. Therefore the crystallinity of low molecular P3HT nanoparticles decreased by PCBM blend. In other words, crystalline structures of the P3HT nanoparticles of high molecular weight were easily disturbed by PCBM blend than those of high molecular weight. We considered that this is due to low crystallinity of the P3HT nanoparticles of low molecular weight which means there are many soft amorphous parts.