Photo voltage

Nakato, Y., Ueda, K., Yano, H., and Tsubomura, H., Effect of microscopic discontinuity of metal over layers on the photo voltages in metal-coated semiconductor-liquid junction photoelectrochemical cells for efficient solar energy conversion, /. Phys. Chem., 92, 2316, 1988. 

Fig. 4. Scheme of the p—n photoefiect (according to S9>) explaining the generation of photo-emf. Note Ue = contact voltage between metal and photoconductor VD = diffusion voltage in the p—n junction Fph = reverse internal photo voltage (in relation to Vq)... 

The performance of the cell can be quantified on a macroscopic level with parameters such as incident photon to current efficiency (IPCE), open-circuit photo voltage (Voc), and the overall efficiency of the photovoltaic cell (i7ceM). 

The maximum open-circuit photo voltage, attainable in a dye-sensitized solar cell, is the difference between the Fermi level of the solid under illumination and the Nemst potential of the redox mediator. However, for these devices this limitation has not been achieved and Voc is in general much smaller. It appears that Voc is kinetically limited and the diode Equation 17.12 can be applied for an n-type semiconductor in a regenerative cell.23... 

Bienvenue et al. [96] used the expression similar to Eq. (40) to describe quantitatively the dependence of the photocurrent through the planar BLM upon the applied photo voltage AU in the System 40 of Table 1. Photocurrent was caused by the the transfer through membrane of ZnTPP+ radical cations. Note that in this case the potential difference affecting the motion of ZnTPP+ cation is equal to only 60% of the external voltage apparently due to the location of ZnTPP+ sufficiently deep below the surface of the membrane. 

Table I Comparison of energy correlations in UHV adsorption experiments (shift of binding energy aEBf, shift of work function a

Both differential electro-absorption and photo-voltage measurements performed by Chichibu et al on GalnN/GaN SQW LEDs and an MQW LD structure [12] also consistently show the main absorption feature at energies well above the dominating luminescence peak. This was interpreted in terms of localisation of excitons at potential fluctuations due to a partial phase separation of GaN and InN. 

Since the nanocrystalline semiconductor particles are not expected to support large depletion layers, the origin of the 600-800 mV open-circuit photo voltage, Kc, has been the subject of much discussion. Neglecting the contacts and leads, l c is de-... 

Y. Nakato and H. Tsubomura, Remarkably high photo voltages generated at n-type silicon semiconductor electrodes coated with extremely small platinum islands, Electrochem. Solid-State Lett. 91, 405, 1987. 

R. Muller, Surface photo voltage studies of silicon electrolyte systems,/. EkctrocJjem. 5oc. 109, 1195, 1962. 

Burnside S., Moser J. E., Brooks K., Gratzel M. and Cahen D. (1999), Nanocrystalline mesoporous strontium titanate as photoelectrode material for photo-sensitised solar devices increasing photo voltage through flatband potential engineering , J. Phys. Chem. B 103, 9328-9332. 

Figure 12.11 Photo voltage spectrum of Gao.7Alo.3As in 0.1 mol dm KOH. Adapted from Hutton and...

Schlichthorl G., Hnang S. Y., Sprague J. and Frank A. J. (1997), Band-edge movement and recombination kinetics in dye-sensitized nanocrystalhne TiOa solar cells a study by intensity-modulated photo voltage spectroscopy , J. Phys. Chem. B 101, 8141-8155. 

The overall conversion efficiency of the dye-sensitized cell is determined by the photocurrent density measured at short circuit (/sc)> the open-circuit photo-voltage (Toe), the fill factor of the cell (FF) and the intensity of the incident light (/g). 

F. 18 Temporal evolution of short circuit photocurrent and open circuit photo-voltage under long-term light soaking of a Z907-sensitized DSC using a non-volatile electrolyte (courtesy of Dyesol)... 

Any change in F,2 caused by illuminating the sample surface or by adsorbates is equal to a change of F, if there are no changes in any other parameters. Moreover, if strong illumination produces flat bands at the semiconductor surface, the saturation value of the surface photo voltage should yield... 

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