Effect photovoltaic

The photovoltaic effect, where an internal elecromotive force is created, was discovered by Becquerel (106) in 1839 in an electrolyte with selenium but the effect in a metal—Se contact was first reported by Adams and Day (107) in 1876. The first practical photovoltaic cell was constmcted by Uljanin (108) in 1888. 

Photovoltaic devices typically consist of a series of thin semiconductor layers that are designed to convert sunlight to dkect-current electricity (see Semiconductors). As long as the device is exposed to sunlight, a photovoltaic (PV) cell produces an electric current proportional to the amount of light it receives. The photovoltaic effect, first observed in 1839, did not see commercial appHcation until the 1950s when photovoltaic modules were used to power early space sateHites. Many good descriptions of the photovoltaic phenomenon are available (7). 

In 1839 Alexandre-Edmtmd Becquerel, a French experimental physicist, did the earliest recorded experiments with the photovoltaic effect. Becquerel discovered the photovoltaic effect while experimenting with an electrolytic cell made up of two metal... 

This section describes the use of oligomer films as active media and demonstrates the importance of the film morphology to both the electrical and the optical properties. This is a factor which has hardly received any attention until now, but one which certainly deserves consideration, for polymers as well. The crucial importance of the microslructurc is equally demonstrated by studies of the photovoltaic effect 1118J this topic will not be dealt with here. 

Williams R (1960) Becquerel photovoltaic effect in binary compounds. J Chem Phys 32 1505-1514... 

The photovoltaic effect is initiated by light absorption in the electrode material. This is practically important only with semiconductor electrodes, where the photogenerated, excited electrons or holes may, under certain conditions, react with electrolyte redox systems. The photoredox reaction at the illuminated semiconductor thus drives the complementary (dark) reaction at the counterelectrode, which again may (but need not) regenerate the reactant consumed at the photoelectrode. The regenerative mode of operation is, according to the IUPAC recommendation, denoted as photovoltaic cell and the second one as photoelectrolytic cell . Alternative classification and terms will be discussed below. 

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 electrochemical photovoltaic effect was discovered in 1839 by A. E. Becquerelt when a silver/silver halide electrode was irradiated in a solution of diluted HN03. Becquerel also first described the photogalvanic effect in a cell consisting of two Pt electrodes, one immersed in aqueous and the other in ethanolic solution of Fe(C104)3. This discovery was made about the same time as the observation of the photovoltaic effect at the Ag/AgX electrodes. The term Becquerel effect often appears in the old literature, even for denoting the vacuum photoelectric effect which was discovered almost 50 years later. The electrochemical photovoltaic effect was elucidated in 1955 by W. H. Brattain and G. G. B. Garrett the theory was further developed... 

At illuminated p-type semiconductors, light energy brings about a shift of the applied cathode potential at which C02 reduction takes place toward a less negative potential by the photovoltaic effect.94 Thus, light energy can be used to reduce the apparent overpotential of C02 reduction. 

Bubbly liquid, structure of, 12 7 Buccal drug dehvery, 9 48 Bucherer reaction, 9 279 Bucherer synthesis, 2 571 Buchner, Edward, 11 8 Buckingham s theorem, 3 589 Buckingham Pi theorem, 11 744 Buckminsterfullerene (Ceo), 22 719 photovoltaic effects in, 22 220 Buckminsterfullerenes, 4 735 12 228. 

Solar Cells—Some nanotubes exhibit a photovoltaic effect and can replace material in solar cells acting as a transparent conductive film allowing light to pass to the active layers and generate photocurrent. It has also been shown that nanotubes can be used in conjunction with other materials to act as an ignition device that is triggered with a simple camera flash. 

Scientists are currently using LB film assemblies as solutions to problems in diverse areas such as microlithography, solid-state polymerization, light guiding, electron tunneling, and photovoltaic effects. In the case of such films as Mg stearate, if a clean glass slide is dipped through the film, a monolayer is adsorbed on the downstroke. Another layer is adsorbed on the upstroke. Under careful conditions,... 

Jenny DA, Loferski JJ, Rappaport P (1956) Photovoltaic effect in GaAs p-n junctions and solar energy conversion. Phys Rev 101 1208-1209... 

Copeland AW, Black OD, Garrett AB (1942) The photovoltaic effect. Chem Rev 31 177... 

Malliaras GG, Salem JR, Brock PJ, Scott JC (1998) Photovoltaic measurement of the built-in potential in organic light emitting diodes and photodiodes. J Appl Phys 84 1583 Gregg BA, Fox MA, Bard AJ (1990) Photovoltaic effect in symmetrical cells of a liquid-crystal porphyrin. J Phys Chem 94 1586... 

Kallmann H, Pope M (1959) Photovoltaic effect in organic crystals. J Chem Phys 30 585 Geacinto N, Pope M, Kallmann H (1966) Photogeneration of charge carriers in tetracene. J Chem Phys 45 2639... 

Ferroelectric substances such as LiNb03 or BaTi03 were found to show anomalous photovoltaic effects (APV) of the order of 103-5 V83). A thin film of a ferroelectric polymer such as PVDF also was found to show APV effects84). Voc of 2.5 x 104 V and short circuit current (Isc) of the order of nA/cm2 were reported. Although the output is very small up to now1, it could be noticed as a specific photoeffect of a thin polymer film. 

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