Surface activity, solar interface

The cost-effective deployment of large areas of solar collectors will most probably be polycrystalline materials, with all index planes emerging at the surface. Therefore, it is not expected that the structural determination of solar materials surfaces will be applied except for a few special cases. However, determining S/S inter facial structures is important, as shown by Figs. 6-9 in Ref. 2. The challenge in solar interface research will be to understand the changes in surface activity of heterogeneous real surfaces and interfaces. Here, SEM and possibly STEM techniques should be used extensively. 

Surface chemistry, in general, is an area in which the ability to selectively modify the chemical and physical properties of an interface is highly desirable. The synthetic chemistry of surfaces is now in a developing stage, particularly with respect to the attachment of electroactive redox sites to metal or semiconductor surfaces (L-3). Single component and bilayer (4) electroactive films have been a field of intense research activity since their applications are apparent in catalysis, solar energy conversion, directed charge transfer, electrochromic devices, and trace analysis. 

We are investigating the effects of binding non-electroactive molecules to electrode surfaces. The attached layer will be sufficiently thin (ca. 1 monolayer) that electron transfer across the electrode/electrolyte interface will not be inhibited. However, other surface properties may be advantageously modified. For semiconductor electrodes, desirable changes include suppression of the photo-activated surface corrosion and shifts in the flatband potential. We are seeking to improve the performance of semiconductor liquid-junction solar cells by these means. 

K. Zhang, D. Kopetzki, P. H. Seeberger, M. Antonietti, E Vilela, Surface Area Control and Photocatalytic Activity of Conjugated Microporous Poly(Benzothiadiazole) Networks. A ew. Cheni.lnt. Ed. 2013,52,1432-1436. S. Peng, L. Tian, J. Liang, S. G. Mhaisalkar, S. Ramakrishna, Polypyrrole Nanorod Networks/Carbon Nanoparticles Composite Counter Electrodes for High-Efficiency Dye-Sensitized Solar Cells. ACS Appl. Mater. Interfaces 2012, 4,397-404. 

The interface between the geosphere and the atmosphere at Earth s surface is very important to the environment. Human activities on the earth s surface may affect climate, most directly through the change of surface albedo, defined as the percentage of incident solar radiation reflected by a land or water surface. For example, if the sun radiates 100 units of energy per minute to the outer limits of the atmosphere, and the earth s surface receives 60 units per minute of the total, then reflects 30 units upward, the albedo is 50 percent. Some typical albedo values for different areas on the earth s surface are evergreen forests, 7-15% dry, plowed... 

In the literature, hybrid solar cells with the active layer composed of CdS-coated cellulose acetate fibers and P3HT were reported by Cortina et al. [81]. Wu et al. reported the enhanced performance of hybrid solar cells made of ZnO nanoflbers by modifying the surface of fibers with CdS [82], To apply more electrospun nanofibers and QDs to hybrid solar cells, the generation of effective interface of electrospun metal oxide nanofibers with QDs before blending with polymer is necessary. Dispersion of QDs in electrospun fibers may be also an alternative way for hybrid applications. 

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