Solar photocurrent spectrum

Fig. 3.25 (a) The solar photocurrent spectrum of a titania nanotube array obtained using data from Fig. 3.19 and Fig. 3.24. (b) The total solar photocurrent obtained by integrated the photocurrent of (a). 

A semiconductor (photovoltaic device, PV), which generates a photocurrent by absorbing sunlight (promoting electrons from the valence to the conduction bands, preferably using the entire solar light spectrum). 

This equation looks similar to Eq. (128). However, there is the essential difference between these two equations. In Eq. (130), we employ the exact semiconductor Green s functions modified by the e-ph interaction. These Green s functions appear in the expressions for the QD Keldysh functions and for the photocurrent. The dependence of the current on a light frequency determines a photocurrent spectrum in a solar cell. 

Campos LM, Tontcheva A, Giines S, Sonmez G, Neugebauer H, Sariciftci NS, Wudl F (2005) Extended photocurrent spectrum of a low band gap polymer in a bulk heterojunction solar cell. Chem Mater 17 4031... 

Campos, L. M. Tontcheva, A. Gtines, S. Sonmez, G. Neugebauer, H. Sariciftci, N. S. Wudl, F. Extended Photocurrent Spectrum of a Low Band Gap Polymer in a Bulk eterojunction Solar Cell, Chem. Mater, 2005,77,4031-4033. 

The integral photocurrent density is given in turn by the overlap integral of the solar emission spectrum Ig(X) and the monochromatic current yield ... 

The photocurrent action spectra of these complexes show broad features covering a large part of visible spectrum, and display a maximum at around 550 nm, where the incident monochromatic IPCE exceeds 85%. These hydrophobic complexes show excellent stability towards water-induced desorption when used as CT photosensitizers in nanocrystalline Ti02-based solar cells.62... 

The HOMO-LUMO gap of the photosensitiser determines the current produced on irradiation. The smaller the size of this gap, the larger the photocurrent, due to the ability of the dye to absorb longer-wavelength regions of the solar spectrum. 

When the interfacial supramolecular triad is irradiated in the presence of I- under solar cells conditions, appreciable photocurrents are obtained. The profile of the photoaction spectrum shows clearly that photoinjection into TiC>2 takes place upon excitation of the ruthenium center. However, the IPCE values obtained are lower than those observed for the model compound, thus suggesting that injection is less efficient in the heterotriad. Of major interest is the mechanism for charge injection. Two different pathways can be envisaged. First, the charge injection may be a two-step process and takes place via the rhodium center as shown in the following equations ... 

Rectification and photovoltaic effects in organic p-n junctions were first reported by Kearns and Calvin [101] and by Meier [3]. The combination of rhodamines or triphenylmethane dyes (both n-type) with merocyanines or phthalocyanines (both p-type) generated photovoltages up to 200 mV and photocurrents of about 10 8 A at low light intensity, with power conversion efficiency much less than 1%. More recent studies have been performed on merocyanine and malachite green [89,90] and on phthalocyanines and TPyP (a porphyrin derivative) [102,103]. These devices showed stronger spectral sensitization and better spectral match to a solar spectrum than those of Schottky barrier cells using only one component. 

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