Semiconducting polymers, exciton dissociation

By making such controlled nanoscale morphology between the donor and the acceptor, and having the donor-acceptor interface vertically oriented to the cathode and the anode, the excitons can be fully dissociated to electrons and holes, and can be efficiently transported to the electrodes before recombination, maximizing both ed and j/cc- One of the major challenges to realize this type of structure is the difficulty to access those periodic pillar and hole structures of tens of nanometer pitch by using the semiconducting polymer and fullerene derivate as a donor and acceptor pair. 

The first reports on photovoltaic effects recorded for organic devices were based on single-layer devices discussed above, which were simply a semiconducting polymer sandwiched between two electrodes with different work functions (exciton dissociation takes place at the interface between the active layer and electrode) (e.g. [65-67]). Although, the devices could show fairly high Vqc of up to 1.7 V, the /sc values were very low, which resulted in very poor PCEs. A significant improvement was achieved by bringing... 

---