Excitons regeneration

Morteani AC, Sreearunothai P, Herz LM, Friend RH, Silva C (2004) Exciton regeneration at polymeric semiconductor heterojunctions. Phys Rev Lett 92 247402... 

High Interface Densities Lower the Barrier-free Capture and Exciton-Regeneration Efficiencies... 

J.G.S. Ramon and E.R. Bittner, Exciton regeneration dynamics in model donor-acceptor pol3Tner heterojunctions, J. Phys. Chem. B, 110, 21001-21009 (2006). 

Dissociated Excitons can be Regenerated via Geminate-Pair and Exciplex Intermediates... 

The most important form of charge-charge interaction that influences DSSC performance is recombination. DSSCs work because geminate recombination, where the photogenerated exciton recombines before it can dissociate, is reduced by the much faster processes of charge injection and dye regeneration as shown in Fig. 4 [12]. Bimolecular recombination, where the electrons injected from the dye molecules reduce tri-iodide ions to iodide (electrolyte DSSCs) or recombine with a hole (SS-DSSCs), is a major source of loss since electron transport to the collector electrode is slow and takes place on similar timescales to these recombination processes. It is hence essential for the success of the dye-sensitized cell that this back reaction is rendered slow enough that electrons injected by the photoexcited dye can be collected efficiently. 

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