The Role of ZnO Particle Size, Shape and Concentration on Liquid Crystal Order and Current-Voltage Properties for Potential Photovoltaic Applications

We investigate the role order plays in the transfer of charges in ZnO nanoparticle - octylcyanobiphenyl (8CB) liquid crystal system for photovoltaic applications as well as the role the nominally 7x5x5nm$^{3}$ or 20x5x5nm$^{3}$ ZnO nanoparticles play in improving that order. Our results for the 5nm nanoparticles show an improvement in the alignment of the liquid crystal with increasing weight percentage of ZnO nanoparticles$^{1}$. Our results for the 7x5x5 nm$^{3}$ sample show that the current is larger than the current obtained for the 5 nm samples. We find that order is improved for concentrations close to 35{\%} wt ZnO for both the 7x5x5 nm$^{3}$ and 20x5x5 nm$^{3}$. We have analyzed the X-ray scans for both the 7x5x5 and the 20x5x5 nm$^{3}$ samples. The signal corresponding to the liquid crystal aligned parallel to the substrate is much smaller than the peak corresponding to the liquid crystal aligned approximately at 70\r{ } with respect to the substrate for the 7x5x5 nm$^{3}$ sample whereas this same peak is comparable or more intense for the 20x5x5 nm$^{3}$ sample. 1. L. J. Mart\'{\i}nez-Miranda, Kaitlin M. Traister, Iriselies Mel\'{e}ndez-Rodr\'{\i}guez, and Lourdes Salamanca-Riba, Appl. Phys. Letts, \underline {97,} 223301 (2010).