A device of this type is similar to the polymer/ metal- nanocomposite memory device described above, except that in this device, the nanocomposite layer between the electrodes consists of a polymer matrix within which are embedded viruses conjugated with metal nanoparticles. In one successful experiment, the nanocomposite consisted of a polyvinyl alcohol matrix with embedded tobacco mosaic viruses to which platinum nanoparticles had been attached by electroless deposition from a platinum- ion solution. A device containing this nanocomposite exhibited switching to the “1” state at a potential of about 3 V and switching to the “0” state at a potential of about -2.4 V.

•Accurate measurement and characterization of organic solar cells.

This body of research addresses the need for improved means of accurately measuring the performances of organic solar cells and using the measurements to accurately characterize the cells according to international norms that, heretofore, have seldom been followed in practice. A simple method of accurately determining the efficiencies of organic solar cells was developed. Different kinds of test cell/reference cell combinations were used to calculate spectral mismatch factors under a standard reference spectrum. Also, the importance of choosing a suitable reference cell for intensity calibration of light sources was demonstrated.

•Effect of self-organization in polymer/ fullerene bulk heterojunctions on the performances of polymer photovoltaic cells.

Some background information on polymer photovoltaic (PV) devices is prerequisite to a meaningful description of this body of research. Of all PV devices, those based on the concept of a bulk heterojunction (BHJ) of donor and acceptor components have exhibited the highest efficiencies reported thus far. Among the most promising donor materials is regioregular poly(3-hexylthiophene) or [RR-P3HT]. Highly efficient solar cells based on BHJs of P3HT with [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM) have been demonstrated. In one recent study, it was found that the efficiencies of solar cells based on P3HT/PCBM can be increased significantly by suitably controlling the rates of growth of the active layers during fabrication of these cells: In particular, it was found that the slow growth of the active layer induced self-organization in the polymer chains, as a result of which there were significant improvements in absorbance and the carrier mobility was observed. This concludes the background information.