Charge-separation efficiency

Another important factor to determine the charge separation efficiency is the distance between and the mutual orientation of the donor and the acceptor in the geminate ion-pair state. The rate of charge recombination depends on whether... 

From the relation between the quenching efficiency and the charge separation efficiency Webber et al. [77] and Morishima et al. [76, 119, 120] have reached the same conclusion that efficient fluorescence quenching static in nature does not lead to efficient charge separation. This conclusion seems to apply generally to... 

Kuczynski and Thorns also studied the formation of MV in CdS solution using a cationic surfactant, cetyltrimethylammonium bromide, as a stabiliasr. In the presence of ethylenediaminetetraacetate (EOTA), the MV " yield was greatly increased. EDTA and MV " form a complex with a resultant negative charge, which is electrostatically bound to the cationic CdS surface. The MV " formed is repelled by the positive charge of the cationic stabilizer, a fact which makes the charge separation efficient. 

Figure 24 Incident photon energy dependence of the surface charge separation efficiency (h" / photon) measured by PITCS. Squares, circles, triangles, and diamonds represent the results obtained for Cr-implanted rutile, Cr-doped rutile, undoped rutile, and anatase Ti02 films, respectively.

Another possibility to determine PGr, which is free of these drawbacks, is electric-field modulation (EFM) of photoluminescence (PL). Electric-field effect on the effective charge separation efficiency (rj0 l) shows up in the varying population of CT states, and consequently, in the varying concentration of the emitting states. It is expected that the field-induced increase in the charge separation efficiency would translate into PL quenching. The ratio (<5) of the PL efficiency in the presence (external electric field (F) would give directly Pgr... 

Kroeze JE, Savenije TJ, Vermeulen MJW, Warman JM. (2003) Contactless determination of the photoconductivity action spectrum, exciton diffusion length and charge separation efficiency in polythiophene-sensitized TiOj bilayers./Rfc yr Chem B 107 7696-7705. 

Recently, geminate polaron pairs have been proposed for polymer-polymer [35,56,57] and polymer-fullerene [58,59] blends as photoinduced intermediates. Here the hole and electron remain coulombically bound across the interface of the donor-acceptor heterojunction. Only via an electric field and/or a temperature-assisted secondary process, these geminate polaron pairs are dissociated, leading to free charge carriers. This can have a considerable effect on the achievable charge separation efficiencies, since the geminate... 

It is difficult to derive simple and absolute rules to improve photoinduced charge separation efficiency in interlocked assemblies, but we have gained... 

A-S-D Triad Monolayer and Second Donor Bilayer Alternate Systems To increase the charge separation efficiency, the increase in the lifetime of the charge separation perpendicular to the film by adding a second door D or an acceptor A to form A-S-D-D or A -A-S-D quadruplet should be examined. In fact, in the reaction center of natural photosynthesis, A -A-S-D structure is used for its efficient charge separation [68]. Because of laboriousness of quadruplet syntheses. 

Jennings JR, Li F, Wang Q (2010) Reliable determination of electron diffusion length and charge separation efficiency in dye-sensitized solar cells. J Phys Chem C 114 14665-14674... 

Kroeze JE, Savenije TJ, Warman JM (2003) Electrodeless determination of the trap density, decay kinetics and charge separation efficiency of dye-sensitized nanoCTystallme Ti02. J Am Chem Soc 126 7608... 

---