Photovoltaics, conducting polymers

J. Kanicki, Polymeric Semiconductor Contacts and Photovoltaic Applications in Handbook of Conducting Polymers (Ed. T. Skolheim), Dekker, New York 1986. 

Given the actual scenario, one can state that the emerging field of nanotechnology represents new effort to exploit new materials as well as new technologies in the development of efficient and low-cost solar cells. In fact, the technological capabilities to manipulate matter under controlled conditions in order to assemble complex supramolecular structures within the range of 100 nm could lead to innovative devices (nano-devices) based on unconventional photovoltaic materials, namely, conducting polymers, fuUerenes, biopolymers (photosensitive proteins), and related composites. 

Photovoltaic (PV) cells, 23 32-53. See also Photovoltaic materials commercial history of, 23 49—51 conducting polymer applications, 7 541 polymethine dyes in, 20 516—517 selenium, 22 100, 103 spectrum and band gap of, 23 37-39 structure of, 22 220-221 third generation, 23 44 workings of, 23 32-37 Photovoltaic detectors, 19 133, 138 Photovoltaic detectors/arrays/focal planes, 19 163-164... 

If one asks what are the applications of conducting polymers, the short answer is none . At the present time (July 1988), the most active field of development is in batteries. There have also been large programmes aimed at developing photovoltaic cells, chemical sensors, semiconductor devices and optical switches. A host of small groups have also investigated the feasibility of various applications. A complete survey is also very difficult because the tendency is to publish completed but unsuccessful studies. 

A solid-state solar cell was assembled with an ionic liquid—l-ethyl-3-methylimidazolium bis(trifluoromethanesulfone)amide (EMITFSA) containing 0.2 M lithium bis(trifluoromethanesulfone)amide and 0.2 M 4-tert-butylpyridine—as the electrolyte and Au or Pt sputtered film as the cathode.51,52 The in situ PEP of polypyrrole and PEDOT allows efficient hole transport between the ruthenium dye and the hole conducting polymer, which was facilitated by the improved electronic interaction of the HOMO of the ruthenium dye and the conduction band of the hole transport material. The best photovoltaic result ( 7p=0.62 %, 7SC=104 pA/cm2, FOC=0.716 V, and FF=0.78) was obtained from the ruthenium dye 5 with polypyrrole as the hole transport layer and the carbon-based counterelectrode under 10 mW/cm2 illumination. The use of carbon-based materials has improved the electric connectivity between the hole transport layer and the electrode.51... 

Poly(3,4-ethylenedioxythiophene) (PEDOT) is a particularly popular conducting polymer as it can have good conductivity and stability and has a low band gap, which is pertinent to its use in photovoltaic devices. A number of authors have now studied the electrochemical synthesis of this polymer in different ionic liquids. Lu et al. [77] first demonstrated the use of [C4mim][BF4] to electrodeposit PEDOT onto ITO, and its application in an electrochromic numeric display. 

It is seen from Table 5.1 that the values of the conversion efficiency in bilayer solar cells also is quite low. As mentioned in the introduction it is difficult to dissociate excitons in the conducting polymers. The Donor/Acceptor (D/A) junction between the polymer and the fullerene is rectifying and can be used for designing photovoltaic cells or photodetectors. In this bilayer cell also the conversion efficiency is low. The cause of the low efficiency is that the charge separation occurs only at the D/A interface that results low collection efficiency. The diffusion length of the exciton is a factor 10, lower than the typical penetration depth of the photon. 

K. Yoshino, K. Tada, A. Fujii, E.M. Conwell, A. Zakhidov, Novel photovoltaic devices based on donor-acceptor molecular and conducting polymer systems, IEEE Trans. Electron Devices 44 (1997) 1315-1324. 

Cso and its derivatives are also easily excited by low-energy light [x]. Thus, a rational combination of electronic properties with chemical reactivity and/or photoactivity has resulted in the preparation of numerous fullerene-derived materials, including low temperature superconducting salts [xi], radical scavengers [xii], materials for - photovoltaic devices and -> conducting polymers [xiii]. 

Miscellaneous bromine uses are in catalysts, fluxes, precious metal recovery, hair care products, food additives, flotation agents in ore treatment, solvents, refrigerants, quartz-halide light bulbs, some lasers, some photovoltaic batteries, and some electrically conductive polymers. 

These novel properties are the basis for a number of application including polymer light emitting diodes (LEDs), polymer light-emitting electrochemical cells (LECs), conducting polymers as electrochromic materials, polymer photodetectors and polymer photovoltaic cells. These application areas are discussed in detail in Section VII. 

Table 1. Summary of photovoltaic performance of some conducting polymers...

Details have appeared of a photovoltaic cell having a high conversion efficiency in which the output efficiency is enhanced by use of a phosphor film containing a terbium bipyridine complex, and of a photorechargeable battery incorporating a conducting polymer of polypyrrole deposited on carbon fibres coated with ferric chloride. The irradiated electrode is thought to possess semiconductor... 

Kazaoui S, Minami N, Nalini B, Kim Y, Hara K (2005) Near-infrared photoconductive and photovoltaic devices using single-wall carbon nanotubes in conductive polymer films. J Appl Phys 98 084314... 

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