Voltage-defined “guardrails” could let graphene separate light-generated charges

Graphene absorbs light and generates electrons and holes, but it has no bandgap, so the energy can’t be harnessed unless the two carriers are separated and sent to different contacts. One known option is to apply a magnetic field to graphene that has been cut or folded, so the edges guide electrons and holes in opposite directions. But creating such edges is difficult and hard to scale to large areas. In the new concept, narrow metal electrodes are placed on an insulating layer above or below planar graphene, and applied voltages create potential barriers in the graphene.

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and TU Dresden, led by Ralf Schützhold, director of the HZDR Institute of Theoretical Physics, have proposed a new way to extract electrical current from light absorbed by graphene, using electrode voltages instead of graphene edges or folds.Graphene absorbs light and generates electrons and holes, but it has no bandgap, so the energy can’t be harnessed unless the two carriers are separated and sent to different contacts. One known option is to apply a magnetic field to graphene that has been cut or folded, so the edges guide electrons and holes in opposite directions. But creating such edges is difficult and hard to scale to large areas. In the new concept, narrow metal electrodes are placed on an insulating layer above or below planar graphene, and applied voltages create potential barriers in the graphene.

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