Light-dependent recombination current

Deviations from this model can be interpreted in terms of a voltage dependent loss of charge separation yield due to either lower electron injection yields or kinetic competition between charge recombination (equation 10.8 and 10.9) and equation 10.10. The first two terms on the right of equation 10.11 compose the usual non-ideal one diode current-voltage characteristic of a solar cell. The final term in equation 10.11 is a light-dependent recombination current, and is required to describe adequately the observed behavior for the cells assembled with the polymer electrolyte with and without plasticizer. 

Fill factor for DSC are hmited in general by series resistance losses, light-intensity dependent recombination, nonideal dark diode currents and, in some cases, shunt resistance losses. 

The overall process performance, as measured by photon efficiency (number of incident photon per molecule reacted, like the incident photon to current conversion efficiency, or IPCE, for PV cells), depends on the chain from the light absorption to acceptor/donor reduction/oxidation, and results from the relative kinetic of the recombination processes and interfacial electron transfer [23, 28]. Essentially, control over the rate of carrier crossing the interface, relative to the rates at which carriers recombine, is fundamental in obtaining the control over the efficiency of a photocatalyst. To suppress bulk- and surface-mediated recombination processes an efficient separation mechanism of the photogenerated carrier should be active. 

When a p-type semiconductor is placed in contact with an n-type semiconductor and the resulting p-n junction is placed in an electrical circuit, the junction can either pass or block DC current, or rectify AC current depending on details of the circuit. The device can emit light due to recombination of holes and electrons at the junction. 

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