Electrical guardrails for charge carriers: A new approach to harness graphene for solar cells

Graphene is a single layer of carbon atoms in which electrons can move with high mobility, making it promising for high-speed electronic components. Yet it is not very efficient at converting light into electricity. While light absorbed by graphene does excite electrons, leaving behind positively charged carriers called 'holes,' the absorbed light energy cannot be harnessed effectively unless electrons and holes are separated and directed to different contacts.