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[17p-P6-11] Miscibility between P3HT nanoparticles with different crystallinity and PCBM
Keywords:semiconductive polymer, nanoparticles, p-n junction
Reprecipitation method, very easy and useful to prepare nanoparticles, can provides monodisperse dispersions of nanoparticles by just 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 dispersions elucidate that the peak corresponding to a lamella crystalline phase of P3HT around the long wavelength region more than 520 nm. The high molecular weight P3HT exhibited the larger absorption peak than that of the low molecular weight one. These indicate that the crystallinity of the P3HT nanoparticles in dispersion depend on the molecular weights. Moreover, the crystallinity of cast films prepared from these nanoparticles was also dependent on molecular weight of P3HT.
Composite films with p-type P3HT and n-type PCBM were prepared by drop casting the blend dispersion from the nanoparticles and PCBM. The absorption spectra of the blend film with the high molecular weight P3HT were similar to the pristine P3HT nanoparticles film. In the case of the low molecular weight P3HT, on the other hand, the absorption peak derived from P3HT crystalline phase significantly decreased by mixing with PCBM. These results clearly indicate that PCBM exhibits high miscibility to the low molecular weight P3HT nanoparticles and suppresses crystal growth of the P3HT. The composite film of the low molecular weight P3HT and PCBM is assumed to form high surface area of p-n junction with the high miscibility.
Composite films with p-type P3HT and n-type PCBM were prepared by drop casting the blend dispersion from the nanoparticles and PCBM. The absorption spectra of the blend film with the high molecular weight P3HT were similar to the pristine P3HT nanoparticles film. In the case of the low molecular weight P3HT, on the other hand, the absorption peak derived from P3HT crystalline phase significantly decreased by mixing with PCBM. These results clearly indicate that PCBM exhibits high miscibility to the low molecular weight P3HT nanoparticles and suppresses crystal growth of the P3HT. The composite film of the low molecular weight P3HT and PCBM is assumed to form high surface area of p-n junction with the high miscibility.