Layers solar cells

Note that a five-layer solar-cell is proposed. However, cost-considerations may make this type of solar cell impractical since the cost of electricity will be too much. A three-layer type of solar-cell has been built which had an efficiency of about 39% (consisting of Si, GaAS and GaN). But until the price of other energy sources mount, or until the cost of gallium-based materials drops, a layered solar-ceU will not be economically feasible. 

Remarkable efforts have been directed to photocatalytic fuel production from sunshine and water for creating energy resources, and now UV light cleavage of water for fuel production is possible. However, conversion of solar visible light to fuels is still under way, and further concentrated researches in this direction are strongly desired. Conversion of solar energy into electricity has been attained by a sensitized TiOz thin layer solar cell to reach nearly 10% efficiency, comparable to that obtained by the amorphous silicone solid cell. This is an important achievement in photocataiysis. 

A single layer solar cell is the simplest solar cell. It is essentially a Schottky diode with a polymer layer sandwiched between two metal electrodes. Several groups have... 

W. A. Miller and L. C. Olsen, Model calculations for silicon inversion layer solar cells, Solar Cells 8 (1983) 371-395. 

Figure 5.11 Back-illuminated cell structure of UV-assisted in-situ polymerized polythiophene/TiO nanotube-based active layer solar cell. Reproduced with permission from Ref. [38].

Figure 21. Inversion layer solar cell structure. (Ref. 58)...

He et al. reported a eopolymer, P22, which was synthesized by Suzuki polycondensation. With P22 PC7iBM (1 4) as the active layer, solar cells with a PFN/Al bilayer cathode displayed PCEs up to 6.07% (Scheme 1.25). ... 

Copper Sulfide—Cadmium Sulfide. This thin-film solar cell was used in early aerospace experiments dating back to 1955. The Cu S band gap is ca 1.2 eV. Various methods of fabricating thin-film solar cells from Cu S/CdS materials exist. The most common method is based on a simple process of serially overcoating a metal substrate, eg, copper (16). The substrate first is coated with zinc which serves as an ohmic contact between the copper and a 30-p.m thick, vapor-deposited layer of polycrystaUine CdS. A layer is then formed on the CdS base by dipping the unit into hot cuprous chloride, followed by heat-treating it in air. A heterojunction then exists between the CdS and Cu S layers. 

Multilayered structures play an important role in the production of, e.g., biomaterials, catalysts, corrosion protectors, detectors/diodes, gas and humidity sensors, integral circuits, optical parts, solar cells, and wear protection materials. One of the most sophisticated developments is a head-up-display (HUD) for cars, consisting of a polycarbonate substrate and a series of the layers Cr (25 nm), A1 (150 nm), SiO, (55 nm), TiO, (31 nm), and SiO, (8 nm). Such systems should be characterized by non-destructive analytical methods. 

Yet another alternative is the thin-film solar cell. This cannot use silicon, because the transmission of solar radiation through silicon is high enough to require relatively thick silicon layers. One current favourite is the Cu(Ga, InjSci thin-film solar cell, with an efficiency up to 17% in small experimental cells. This material has a very high light absorption and the total thickness of the active layer (on a glass substrate) is only 2 pm. 

A photovoltaic cell (often called a solar cell) consists of layers of semiconductor materials with different electronic properties. In most of today s solar cells the semiconductor is silicon, an abundant element in the earth s crust. By doping (i.e., chemically introducing impurity elements) most of the silicon with boron to give it a positive or p-type electrical character, and doping a thin layer on the front of the cell with phosphorus to give it a negative or n-type character, a transition region between the two types... 

The chapter is organized as follows the second section will discuss the photophysics of conjugated polymer/fullerene composites as a standard model for a charge-generating layer in plastic solar cells. Pristine polymer devices will be discussed in the third section while bilayer and interpenetrating network devices are presented in Sections 4 and 5. Section 6 contains some remarks on large area plastic solar cells and Section 7 conclusions. 

In two-component charge transfer systems, such as in the bulk-heterojuncdon solar cells presented here, deviations of the V,K. from the results of pristine single layer or bilayer devices are expected for two reasons first, some pan of the available difference in electrochemical energy is used internally by the charge transfer to a lower energetic position on the electron acceptor second, the relative posi-... 

Preliminary measurements with space-resolved PMC techniques have shown that PMC images can be obtained from nanostructured dye sensitization cells. They showed a chaotic distribution of PMC intensities that indicate that local inhomogeneities in the preparation of the nanostructured layer affect photoinduced electron injection. A comparison of photocurrent maps taken at different electrode potentials with corresponding PMC maps promises new insight into the function of this unconventional solar cell type. 

Anodization generally results in the formation of films with limited thickness, uncertain composition, defects, and small crystallite size. Thus, the barrier nature of the n-type semiconducting CdS film obtained in the previous manner makes it too thin to form the basis of Cu2S/CdS or CdTe/CdS solar cells by the normal dipping process. Heterojunction cells of low efficiency have, however, been made by anodization followed by vacuum deposition of the added layer (CU2S). 

Electrodeposition of copper indium disulfide (CulnS2) has been reported [180-182], In a typical instance, single-phase polycrystalline CuInS2 thin films composed of 1-3 fim sized crystallites were grown on Ti by sulfurization of Cu-ln precursors prepared by sequentially electrodeposited Cu and In layers [183]. In this work, solar cells were fabricated by electrodepositing ZnSe on CuInS2. Cyclic... 

Aqueous cathodic electrodeposition has been shown to offer a low-cost route for the fabrication of large surface n-CdS/p-CdTe solar cells. In a typical procedure, CdTe films, 1-2 xm thick, are electrodeposited from common acidic tellurite bath over a thin window layer of a CdS-coated substrate under potential-controlled conditions. The as-deposited CdTe films are stoichiometric, exhibit strong preferential (111) orientation, and have n-type conductivity (doping density typically... 

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