High‑Efficiency Graphene Solar Cells: 9% Power Conversion with TFSA Doping

Graphene: A Unique 2‑D Material

Graphene is a single‑atom‑thick sheet of carbon arranged in a honeycomb lattice. Its electrons move at near‑relativistic speeds, behaving like massless Dirac particles. This gives graphene exceptional electrical conductivity, mechanical strength, and complete optical transparency, allowing it to absorb light across the visible spectrum.

Solar Cells Made From Graphene

Early graphene‑based photovoltaic devices delivered modest efficiencies—around 1.9%. Recent work from the University of Florida in Gainesville has changed the narrative. By incorporating the organic dopant trifluoromethanesulphonyl) amide (TFSA) into the graphene layer, researchers achieved a record 9% power‑conversion efficiency, nearly five times higher than undoped cells.

Device Structure

The cells consist of a TFSA‑doped graphene sheet transferred onto a high‑quality silicon wafer to form a graphene/silicon Schottky junction. Because graphene is transferred gently, the interface remains pristine; any disorder would act as a charge trap, shortening carrier lifetimes and reducing efficiency. A clean interface preserves the strong electric field needed for efficient charge separation.

How It Works

When sunlight strikes the cell, photons generate electron‑hole pairs. The Schottky barrier between graphene and silicon separates these carriers: electrons move into silicon while holes remain in graphene. Electrodes attached to each material collect the charges, producing an electric current.

Doping graphene with TFSA shifts its Fermi level, which in turn enhances the electric field across the junction. This stronger field accelerates carrier separation and collection, leading to the substantial boost in power output.