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The dynamics of carrier recombination and transport of two CuInS2 superstrate solar cells was studied by intensity modulated photovoltage and photocurrent spectroscopy (IMVS and IMPS respectively). For the analysis of the resulting data two different approaches were implemented. In the first approach, the typically used analysis in Dye Sensitized Solar Cells (DSSC) was adapted to obtain the characteristic times of the processes involved. The second approach was based on the fittings of both the IMVS and IMPS data to the solution of the continuity equation. These fittings allow the calculation of different dynamic parameters of the cells. Moreover, consistency between the obtained parameters was observed, in good agreement with the typical analysis for DSSC. The resulting dynamics was associated with the presence and distribution of defect states among the samples. Moreover, from the performed analysis, a relation between the results and the post-treatment applied to the solar cells could be established. The difference in the dynamics of the cells is mainly observed in the difference between the electron lifetimes of both solar cells. [ABSTRACT FROM AUTHOR]

Herein we report the characterization and photoelectrochemical behavior of nanocrystalline TiO2 films modified with some alizarin derivatives. Particularly, alizarin complexone (3-[N,N-bis(carboxymethyl)-aminomethyl]-1,2-dihydroxyanthraquinone) and its Fe(ii) and Fe(iii) metal complexes have been examined. Based on UV-Visible and Raman spectroscopic studies we proposed that AC forms a tridentate complex with titanium dioxide involving the 2-OH and (methylimino) diacetate groups, while Fe(ii) and Fe(iii) AC-complexes bind to titanium dioxide through the carbonyl (C=O) and hydroxyl (OH) groups at the 1,9 positions of the alizarin framework. These findings allow the design of different nanostructures with diverse photoelectrochemical behavior. Analysis of the j–V curves reveals a sign reversal at −90 mV and −100 mV upon the excitation of AC@TiO2 and [FeIIIAC]@TiO2 photoelectrodes, respectively, whereas [FeIIAC]@TiO2 displays only anodic photocurrents. A description involving both electronic and geometric factors to account for these differences is proposed. [ABSTRACT FROM AUTHOR]