Charge transport, interlayer

As discussed in the previous section, one of the major DSSC bottlenecks is the charge transport across the electrode network. Recently, different groups have demonstrated that implementation of nanocarbons in the form of (i) interlayers on the bottom and/or on top of the mesoporous film, and (ii) dopants inside the electrode network, is a very powerful strategy to overcome this issue. In this section, the most relevant aspects are outlined. 

The pronounced anisotropy of the electrical conductivity in layered compounds (8,15) suggests that the charge carriers move, on their way to the surface, predominantly within the layers, i.e. parallel to the main surface as shown in Fig. 14 (in which the relative path of the charge carriers within the layers is compressed). The random character of interlayer charge transport due to extrinsic conduction leads to a variety of possible paths, two of which are represented in Fig. 14. 

Figure 14. Schematic of trajectories of minority carriers for an ideally smooth surface in contact with an electrolyte. The random character of the interlayer charge transport is also indicated (small arrows). The average minority carrier motion is given by the large arrows.

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