Solar semiconductor/conducting-polymer

Conductive polymers are useful semiconductors or coating materials to construct solar cells. A new photodiode is proposed to be made from a film of a polymer metal complex. Immobilized catalysts on polymers are used for solar energy storage systems. 

Thin films of conductive polymers like polypyrrole, polyaniline, etc are also used for the surface modification of the semiconductor electrodes [26, 27]. Their performance mechanism has not yet been deciphered. Most likely, the coating is a combination of a protective film and the charge carrier, the more so that reversible redox couples are used to be introduced into films [28], as well as catalytically-active admixtures like Ru02 [29]. Such films were used to stabilize a promising "solar" electrode material, amorphous silicon [30]. 

Since protection of electrodes against corrosion in the photoelectrolysis cells is a question of vital importance, many attempts have been made to use protective films of different nature (metals, conductive polymers, or stable semiconductors, eg., oxides). Of these, semiconductive films are less effective since they often cause deterioration in the characteristics of the electrode to be protected (laying aside heterojunction photoelectrodes specially formed with semiconducting layers of different nature [42]). When metals are used as continuous protecting film (and not catalytical "islands" discussed above), a Schottky barrier is formed at the metal/semiconductor interface. The other interface, i.e., metal/electrolyte solution is as if connected in series to the former and is feeded with photocurrent produced in the Schottky diode upon illuminating the semiconductor (through the metal film). So, the structure under discussion is but a combination of the "solar cell" and "electrolyzer" within the photoelectrode Unfortunately, light is partly lost due to absorption by the metal film. 

As well as battery apphcation, conducting polymers may also find uses as electromagnetic shielding because they tend to absorb low-frequency radiation, or as parts of solar cells and semiconductors. Their use as heating elements in thin-wall coverings and in wire and eable applications is also being investigated. 

The present 10 volume handbook has a much broader scope. It includes semiconductor materials, quantum wells and quantum dots, liquid crystals, conducting polymers, laser materids, photoconductors, electroluminescent and photorefractive materials, nanostructured, supramolecular, and self-assembled materials, ferroelectrics, and superconductors. Applications of these materials in photoconductors, optical fibers, xerography, solar cells, dynamic random access memory, and sensors are described. The Handbook contains contributions by 180 leading experts from 25 different countries. It truly represents the worldwide research efforts and results that support the global market of optoelectronics. All scientific and technical workers in this broad field are indebted to the contributing authors, the editor and Academic Press for publishing this comprehensive handbook for the new millennium. It will support further growth in a field that already has surpassed my wildest expectations of 40 years ago. 

Poly(3,4-ethylenedioxythiophene) is one of the most durable and transparent conducting polymers with a very good thermal stability and high conductivity (ca. 200 S cm ). The bandgap of PEDOT can be varied between 1.4 and 2.5 eV. In the state of complete oxidation, its conductivity decreases and the polymer behaves hke a semiconductor. Moreover, PEDOT demonstrates an electrochromic effect. In the reduced state it has dark blue color, and while oxidized it is colorless (Groenendaal et al., 2000). Apart from apphcations in electrochemistry, such as batteries, fuel cells, organic solar cells, sensors, and biosensors, PEDOT is widely used in optoelectronics (Krzyczmonik and Socha, 2013). 

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