Photon conversion

Nozik, A. J. 2007. Third generation solar photon conversion. Abstracts of Papers, 233rd ACS National Meeting (Chicago, IL March 25—29). PHYS-082. 

So, 2.1 x 10 5 nm radiation, by virtue of possessing the smallest wavelength in the set, has the greatest energy per photon. Conversely, since 4.1 x 103 nm has the largest wavelength, it possesses the least amount of energy per photon. 

For a single band gap system, two basic approaches for the conversion of hot carriers into electricity or chemical energy have been proposed to enhance the efficiency of photon conversion (a) extraction of the hot carries before they cool, with the production of an enhanced photovoltage [35] (b) production of two or more electron-hole pairs per photon absorbed, with photocurrent enhancement [36, 37]. 

A.J. Nozik, Exdton multiplication and relaxation dynamics in quantum dots Application to ultrahigh-efficiency solar photon conversion, Inorg. Chem. 44 (2005) 6893-6899. 

Photoelectrochemical cells for solar photon conversion are usually designed to produce either electric power or solar fuels this book focuses on the latter. Power-producing solar cells are designed to be operated at their maximum-power point to produce electric power at the energy conversion efficiency... 

The use of nanoscale constructs has given a further major boost to solar photon conversion. The scale of nanosized materials such as quantum dots and nanotubes, conventionally taken to lie in the range 1-100 nm, produces very interesting size quantisation effects in optoelectronic and other properties bandgaps shift to the blue, carrier lifetimes increase, potent catalytic properties emerge and constructs with very high surface-to-volume ratios can be made. Incorporation of nanoscale structures in photovoltaic devices allows these unique properties to be exploited, with conversion efficiencies above the detailed balance limit becoming possible in principle. 

All in all, we can predict—or even allow ourselves to imagine—further exciting advances in the science and technology of solar photon conversion in nanostructured and photoelectrochemical systems in the years ahead. 

There are two fundamental approaches for enhancing the solar photon conversion efficiency increased photovoltage (Boudreaux et al, 1980 Ross and Nozik, 1982) and increased photocurrent (Kolodinski et al, 1993 Landsberg et al, 1993). These can be accessed, in principle, in at least three different QD solar cell configurations these configurations are shown in Fig. 3.19 and described below. 

Vol. 3 Nanostractured and Photoelectrochemical Systems for Solar Photon Conversion... 

NANOSTRUCTURED AND PHOTOELECTROCHEMICAL SYSTEMS FOR SOLAR PHOTON CONVERSION... 

It is this new generation of solar photon conversion devices that are covered in this book. They are less highly developed than those described in Volumes 1 and 2 of this series, bnt their promise is at least as great. That promise is two-fold on the one hand highly efficient devices with sophisticated architectures in which the Shockley-Queisser limit on efficiency is finally overcome, and on the other very low-cost plastic or organic-based devices that are cheap enough to be disposable. 

Renewable energy (wind, biomass, geothermal, photovoltaics, and direct photon conversion—for example, solar photovoltaic water splitting) will play an increasingly important role. (Nathan Lewis, Ralph Overend)... 

FIGURE 8.16 Schematic drawing of experimental setup used for incident photon conversion efficiency measurements. 

B.R. Sankapal, S.D. Sartale, M.C. Lux-Steiner, A. Ennaoui, Chemical and electrochemical synthesis of nanosized Ti02 anatase for large-area photon conversion , Comptes Rendus Chimie, 9, 702-707, (2006). 

Peter, LM. and Tributsch, H. (2008) In Nanostructured and Photoeletrochemical Systems for Solar Photon Conversion. Editors M.D. Archer and A.J. Nozik. Imperial College Press, London. 

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