Photocurrent conversion efficiency

In nonbiological applications, mixed ruthenium complexes of bipyridyl ligands and substituted pteridine diones have been used as components of photovoltaic cells <2002JPH167>. When fabricated into sol-gel processed titanium oxide electrodes, these complexes achieved photocurrent conversion efficiency in the range 20 8%. 

Figure 3 Incident photocurrent conversion efficiencies (IPCE) observed for the tri-nuclear complex ([fraw-(NC)Ru(py)4(CN)2]Ru(dcbH2))2 + on a 6-(im-thick Ti02 photoanode in the presence of 0.3 M I2 and 0.03 M Lil.

Dlocik et al. [72] have taken a general approach to the generation collection problem which considers voltage dependent rate constants for electron extraction/injection at the TiO substrate interface. The diffusion controlled limit is obtained by making the rate constant for electron extraction sufficiently large. For illumination from the electrolyte side, the ac photocurrent conversion efficiency d>([Pg.271]

Jarrett H. S. (1981), Photocurrent conversion efficiency in a Schottky barrier , /. Appl. Phys. 52, 4681 689. 

Here, the ratio of the photocurrent, photo to the incident photon flux, 70, (corrected for reflection) is the photocurrent conversion efficiency, Since eqn. (3) takes no account of recombination in the space-charge region or at the interface, it represents an upper limit to the photocurrent conversion efficiency. Several treatments of recombination have been discussed in the literature [7], but they lie outside the scope of the present chapter. 

Photocurrent spectroscopy provides a powerful approach to the determination of the absorption spectra of thin semiconducting or insulating films. Equation (6c) can be rearranged to show explicitly the relationship between photocurrent conversion efficiency and absorption coefficient... 

However, this equation can only be used to obtain the film thickness or absorption spectrum if the assumptions made in its derivation are valid if recombination is important, the photocurrent conversion efficiency will be reduced and, as a consequence, values of a or Lf derived by analysis of the photocurrent spectrum will be too low. Similarly, if the assumption that W > Lt is incorrect, the analysis will underestimate the absorption coefficient. If, on the other hand, recombination is negligible and W > Lf, the... 

Fig. 13. (a) Spectrum of anodic photocurrent conversion efficiency of anodised bismuth at 3 V vs. SCE. (b) Spectrum of cathodic photocurrent conversion efficiency of the same film at - 0.55 V vs. SCE. The additional low-energy response is due to internal photoemission. (Reproduced with permission from ref. 29.)... 

Photoeffects at copper electrodes coated with copper phenylacetylide (CuPA) films were discovered during an in-situ laser Raman investigation [35], where substantial cathodic photocurrents were observed. A subsequent detailed study by photocurrent spectroscopy showed that the photocurrent conversion efficiency was of the order of a few percent, even for thicker films which absorbed a substantial fraction of the incident light. Figure 18 contrasts the photocurrent excitation spectrum with the absorption spectrum measured on an OTE coated with the CuPA polymer. The coincidence in the vibrational structure in the two spectra is striking, suggesting that the absorption gives rise to a state with considerable molecular character. 

Schoenmakers et al. [77] have used IMPS, PEIS and potential dependent photoluminescence to study the competition between charge transfer and recombination at ZnO electrodes. Their results indicate that recombination in the bulk solid as well as via surface states is responsible for the reduction in photocurrent conversion efficiency in the photocurrent onset region. 

For illumination from the electrolyte side, the ac photocurrent conversion efficiency 0(w) = jphowNlo is given by [90]... 

In a study of anodic oxide films grown on titanium [740], photocurrent spectra were converted, yielding photocurrent conversion efficiencies 0 as a function of electrode potential (see Fig. 5.129). 

Fig. 5.129. Potential dependence of the photocurrent conversion efficiencies at various electrode potentials (vs. scE indicated) for a titanium electrode in contact with an aqueous electrolyte solution of 1 M H2SO4 (based on data in [740])...

J. van de Lagemaat, N. G. Park, A. J. Frank, I nfluence of electrical potential distribution, charge transport, and recombination on the photopotential and photocurrent conversion efficiency of dye-sensitized nanocrystalline Ti02 solar cells a study by electrical impedance and optical modulation techniques, J. Phys. Chem. B 2000, 104(9), 2044-2052. 

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