Graphene absorbs light and produces electrons and positively charged “holes,” but getting that energy out as electricity is difficult: the two kinds of charge must be separated and guided to different contacts. A theoretical study described in a Phys.org report proposes using electrical voltages to do that, with a magnetic field helping steer the charges. The report is credited to Simon Schmitt and provided by the Helmholtz Association of German Research Centres.
The proposal addresses a difference between graphene and familiar solar-cell materials such as silicon. Silicon’s bandgap plays a key role in converting light into electrical energy; graphene has no such gap. The report says this makes it necessary to find another way to direct the charges created when graphene absorbs light.
The proposed mechanism combines a magnetic field applied perpendicular to the graphene sheet with voltage-created potential barriers. The field bends electron and hole paths into curves in opposite directions. In earlier approaches, physical edges cut or folded into graphene act as barriers that guide the charges apart. The new concept would use narrow metal electrodes above or below the graphene, separated from it by an insulating layer. Voltages on those electrodes would create barriers in the sheet, serving as adjustable “guardrails” without requiring edges to be made in the material.
The barrier polarity determines which charge can pass. According to the report, a negative barrier reflects electrons while allowing holes through; a positive one does the reverse. With the magnetic field curving their paths, electrons and holes could be directed toward opposite contacts. The researchers’ calculations identify conditions the design would need to meet: barriers must be high and wide enough to keep electrons from simply passing through, and electrode spacing must match the circular paths. Those paths depend on the magnetic-field strength and the energy of the absorbed light.
The study is identified as “Magnetophotoelectric effect in graphene via tailored potential landscapes,” by Joris Josiek and colleagues, published in Physical Review Applied in 2026. The report describes the work as a proposal assessed through calculations, not a demonstration of a working solar cell. For a possible first experimental setup, it outlines graphene between transparent insulating layers with fine metal strips across the top. It says micrometer-scale spacing would be needed for infrared conversion and that the team’s calculations indicate a magnetic field around 0.1 tesla should be sufficient. The report says HZDR is planning experiments to assemble and test the components.
If experiments support the calculations, adjustable voltages could let the system be adapted to different light energies. Arrays of electrodes might also extend the approach across larger graphene surfaces without cutting or folding the sheet. The report highlights infrared solar cells as one possible long-term application: graphene can absorb infrared photons whose energy is too low to generate electron-hole pairs in conventional silicon solar cells. That possibility does not establish how efficiently a graphene device would turn infrared light into useful electricity. The report also mentions possible sensors for visible or infrared light and graphene electronics with variable charge paths.
There is some earlier experimental context, but it does not test the new electrode design. The report says Ralf Schützhold, director of the HZDR Institute of Theoretical Physics, points to experiments using graphene edges that confirmed a theoretical prediction and produced a stronger signal than expected. The voltage-controlled barriers are a separate proposed approach, and the report says experiments to test them are still being planned.
