Abstract:
To reduce the costs of polymer solar cells it is important to develop a fully solution processed route. Although several successful generic routes to solution processed hole collecting electrodes have been shown, this is not the case for the electron collecting electrode of polymers cells, as it is hard to find a solution processable low workfunction, low ohmic, electron collecting electrode. Here an efficient recombination layer is described formed by the combination of ZnO and PEDOT and applied in an electron collecting layer. The ZnO contacts the conduction band of the acceptor material to collect electrons from the absorber layer. Since ZnO is a wide bandgap material, it also acts as an exciton and hole blocking layer. Electrons collected by the ZnO layer easily recombine with holes from the highly doped, high conductive PEDOT layer. The performance of a device with a recombination layer is compared in a standard as well as inverted polymer solar cells. The performance of the device with the PEDOT/ZnO recombination layer deviates less than 10 % from similarly processed standard and inverted device structures.
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