Evidence of Harvesting Electricity by Exciton Recombination in an n−n Type Solar Cell

摘要

Significant works,1–5 mainly on generating more free carriersnfrom excitons, have been conducted since the first efficientndonor-acceptor (D-A) type organic solar cell reported in the laten1980s.6 Up to now all organic solar cells,1–9 either small moleculeornpolymer-based ones, are fabricated with a donor and an acceptornmaterial to form a D-A interface, where the photogeneratednexcitons are dissociated for free carriers. Here we report a newnn-n type heterojunction organic solar cell based on perfluorinatednhexadecafluorophthalo-cyaninatozinc (F16ZnPc) and fullerene (C60).nUnlike the exciton dissociation in the existing D-A heterojunctionnorganic solar cells, the recombination of excitons at the interfacenis used to produce free carriers. The recombination of electronsnfrom F16ZnPc with holes from C60 at the F16ZnPc-C60 interfacenfrees their counterpart carriers (electrons at C60 side and holes atnF16ZnPc side respectively), which are separated by a built-innelectric field originated from the work function difference betweennthe two electrodes and then collected by two electrodes to generatenthe photocurrent.