Solar devices

Singh P, Singh R, Gale R, Rajeshwar K, DuBow J (1980) Surface charge and specific ion adsorption effects in photoelectrochemical devices. J Appl Phys 51 6286-6291 Bard AJ, Bocarsly AB, Pan ERF, Walton EG, Wrighton MS (1980) The concept of Fermi level pinning at semiconductor/liquid junctions. Consequences for energy conversion efficiency and selection of useful solution redox couples in solar devices. J Am Chem Soc 102 3671-3677... 

A new approach to improve the performance of solar devices using natural pigments is to employ carbon nanotube (CNT)-based counter-electrodes. As previously reported, the excited dye transfers an electron to Ti02 and so it acquires a positive charge. Then, the cationic molecule subtracts an electron from the counterelectrode which is transported by the electrolyte. This reaction is usually catalyzed by means of conductive and electrocatalytically active species for triiodide reduction of carbon coatings. CNTs have a high superficial area, which represents a very... 

Fischer, Ch.-H. Bar, M. Glatzel, Th. Lauermann, I. Lux-Steiner, M. C. 2006. Interface engineering in chalcopyrite thin film solar devices. Sol. Energy Mater. Sol. Cells 90 1471-1485. 

Graphene has also been studied as the acceptor within the active layer of the cell (see Fig. 35). In these studies hydrophilic GO and solution-processable functionalized graphene (SPFGraphene) act as efficient acceptor moieties [272, 280]. In these cells it has been determined that the energy conversion efficiency depends on the graphene content and the annealing temperature of the cell when constructed (see Fig. 36). Conversion efficiencies vary from 0.034 to 1.4% for SPFGraphene [280] and from 2.1 to 3.8% for GO based solar devices [277]. 

Figure 17.3 Best laboratory efficiencies obtained for various solar devices.

Dye-sensitized solar cells (DSSCs) are photoelectrochemical solar devices, currently subject of intense research in the framework of renewable energies as a low-cost photovoltaic device. DSSCs are based upon the sensitization of mesoporous nanocrystalline metal oxide films to visible light by the adsorption of molecular dyes.5"7 Photoinduced electron injection from the sensitizer dye (D) into the metal oxide conduction band initiates charge separation. Subsequently, the injected electrons are transported through the metal oxide film to a transparent electrode, while a redox-active electrolyte, such as I /I , is employed to reduce the dye cation and transport the resulting positive charge to a counter electrode (Fig. 17.4). 

Now, consider stability. If a satisfactory initial system or component performance and cost are assumed, then in many cases the critical issue is to maintain the physical behavior of materials adjoining an interface for up to 30 years. The physical behavior may include properties that directly influence solar device performance, such as reflectance, transmittance, absorptance, emittance, and photovoltaic efficiency or solar device performance may be indirectly affected by properties such as adhesion, permeability, photo-oxidative stability, or interdiffusion. The required stability of interfaces in SECS components is counter to basic physics and chemistry, because atoms at interfaces must be more reactive and thermodynamically less stable than when in the bulk of materials (2). Yet, the density of solar energy requires deploying systems with large interfacial... 

S/S, S/L, and S/G interfaces of many types occur in most solar devices, often with several in close proximity. To extrapolate from short-term laboratory behavior to 30-year lifetimes requires an atomic-level mechanistic understanding of the degradation processes occurring at interfaces. The latter, in turn, require using state-of-the-art methods of microcharacterization that yield structural, chemical, or electronic information with a lateral spatial resolution approaching atomic dimensions (14). 

In our laboratory we have extensively studied inorganic ions in glasses as possible materials for laser and solar devices. The photostability of inorganic ions in glasses as well as in crystals is extremely high as evidenced by the variety of inorganic minerals... 

Burnside S., Moser J. E., Brooks K., Gratzel M. and Cahen D. (1999), Nanocrystalline mesoporous strontium titanate as photoelectrode material for photo-sensitised solar devices increasing photo voltage through flatband potential engineering , J. Phys. Chem. B 103, 9328-9332. 

Two methods may be used for measurement as a basis for enforcement the solar envelope and the solar window methods. The former would define the maximum build-able volume possible on any site without casting undue shadows outside the site boundaries (Fig. 22). The latter would define in three-dimensional terms the solid angle subtended at an existing (established) solar device that... 

Spray pyrolysis technique has been used to deposit polycrystalline thin films comprising of CuInSa nanocrystals onto glass substrates. p-XRD studies demonstrate that the films have a chalcopyrite structure with preferred orientation along (112) lattice plane. Average diameter of the nanocrystals, as determined by SEM and TEM images, was found to be about 40-60 nm while band gap calculated through optical absorption studies was found to be 1.55 eV. A solar device fabricated by using these films demonstrated a power conversion efficiency of 7.60%. 

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