Solid photovoltaics

Sperr-klmke, /. catch, pawl, ratchet, detent, -kreis, m. block circuit, wave trap circuit, -metail, n. ply metal, -rad, n. ratchet wheel, cog wheel, -schichtenzelle, /. solid photovoltaic cell, -ung, /. shutting, etc. (see sperren). -ventil, n. stop valve, check valve, shut-off valve, -waffe, /. defensive weapon, -wasser, n. sealing water. 

As it has been described in various other review articles before, the conversion efficiencies of photovoltaic cells depend on the band gap of the semiconductor used in these systems The maximum efficiency is expected for a bandgap around Eg = 1.3eV. Theoretically, efficiencies up to 30% seem to be possible . Experimental values of 20% as obtained with single crystal solid state devices have been reported " . Since the basic properties are identical for solid/solid junctions and for solid/liquid junctions the same conditions for high efficiencies are valid. Before discussing special problems of electrochemical solar cells the limiting factors in solid photovoltaic cells will be described first. 

Selenium exhibits both photovoltaic action, where light is converted directly into electricity, and photoconductive action, where the electrical resistance decreases with increased illumination. These properties make selenium useful in the production of photocells and exposure meters for photographic use, as well as solar cells. Selenium is also able to convert a.c. electricity to d.c., and is extensively used in rectifiers. Below its melting point selenium is a p-type semiconductor and is finding many uses in electronic and solid-state applications. 

Photovoltaic (PV) solar cells, which convert incident solar radiation directly into electrical energy, today represent the most common power source for Earth-orbiting spacecraft, such as the International Space Station, where a photovoltaic engineering testbed (PET) is actually assembled on the express pallet. The solid-state photovoltaics, based on gallium arsenide, indium phosphide, or silicon, prove capable, even if to different extents and with... 

In any case, it is perceived from the above discussion that the problem of longterm chemical stability of polycrystalline semiconductor liquid junction solar cells is far from being solved. Still, as already pointed out in the early research, any practical photovoltaic and PEC device would have to be based on polycrystalline photoelectrodes. Novel approaches mostly involving specially designed PEC systems with alternative solid or gel electrolytes and, most importantly, hybrid/sensitized electrodes with properties dictated by nanophase structuring - to be discussed at the end of this chapter - promise new advances in the field. 

The photovoltaic implications of the solid-state chemistry of CuInSe2, particularly where deviations from the 1 1 2 stoichiometry along the Cu2Se-In2Sc3 tie line are concerned, have been studied, and results of measurements of some photoelectrochemical properties along this tie line (e.g., for 283) have been given [169]. 

Kruger J, Bach U, Plass R, Cevey L, PiccireUi M, Gratzel M (2001) High efficiency solid-state photovoltaic device due to inhibition of interface charge recombination. Appl Phys Lett 79 2085-2087... 

The term photovoltaic effect is further used to denote non-electrochemical photoprocesses in solid-state metal/semiconductor interfaces (Schottky barrier contacts) and semiconductor/semiconductor pin) junctions. Analogously, the term photogalvanic effect is used more generally to denote any photoexcitation of the d.c. current in a material (e.g. in solid ferroelectrics). Although confusion is not usual, electrochemical reactions initiated by light absorption in electrolyte solutions should be termed electrochemical photogalvanic effect , and reactions at photoexcited semiconductor electodes electrochemical photovoltaic effect . 

The best parameters of the I /I2 cell were achieved by using a non-aqueous electrolyte and the anatase electrode of nanometer-sized particles, sensitized with RuL ju - (NC)Ru(CN)(bpy)2)2. In 1991, B. O Regan and M. Gratzel described a cell attaining parameters competitive to commercial, solid-state photovoltaic devices. 

M.S. Wrighton, M.I.T. What is the basis for an estimate of 57o efficiency for photosynthesis and the 187> for a comparison with solid state photovoltaics for electricity generation ... 

Yamaguchi, T. Yamamoto, Y. Tanaka, T. Yoshida, A. 1999. Preparation and characterization of (Cd,Zn)S thin films by chemical bath deposition for photovoltaic devices. Thin Solid Films 343-344 516-519. 

Olson, D. C. Piris, J. Collins, R. T. Shaheen, S. E. Ginley, D. S. 2006. Hybrid photovoltaic devices of polymer and ZnO nanofiber composites. Thin Solid Films 496 26-29. 

The discovery of the EL in PPV in 1990 resulted in a tremendous growth of interest in polymer LEDs (PLEDs) [1]. Since then, numerous derivatives and analogs of PPV with tailored light-emitting properties have been synthesized, and a number of reviews and accounts described the synthesis and the EL properties of these materials [6 16]. Many new applications of PPV polymers, as solid-state lasing [17,18], photovoltaics [19], etc., have been... 

Attaching perylene moieties as side groups allows achievement of high concentration without affecting the electronic structure of the polymer backbone. Putting 16% perylene moieties as side chains predictably results in more efficient energy transfer, observed with polymer 360, both in solution and solid state (emission band at 599 nm). Although no PLED device with 360 has been reported, this material showed excellent performance in solar cells (external photovoltaic QE = 7%, in blend with PPV) [434]. 

Biogas (Solid) Biomass Biowaste Geothermal electricity Flydro large-scale Hydro small-scale Photovoltaics Solar thermal electricity Tide wave Wind onshore Wind offshore... 

Wind offshore Wind onshore Tide and wave Solar thermal electricity Photovoltaics Hydro small-scale Hydro large-scale Geothermal electricity Biowaste (Solid) biomass (Solid) biomass co-firing Biogas... 

A.N. Tiwari, Thin film chalcogenide photovoltaic materials, Thin Solid Films, 480-481 (2005) 1 and following papers. M.A. Green, Third generation photovoltaics Ultrahigh conversion efficiency at low cost, Prog. Photovolt ... 

While the application of photovoltaic cells has been dominated by solid-state junction devices principally made from silicon, recent work in this field offers the prospect of efficient solar-energy conversion by novel methods. 

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