Shao-Yu Chen and colleagues at the Institute of Atomic and Molecular Sciences have developed a method for incorporating chlorophyll into graphene transistors to make light-activated switches.
Their phototransistor design consists of two silver electrodes connected by a sheet of graphene. The graphene is covered by a layer of chlorophyll using the drop-casting method, which involves placing a drop of liquid containing chlorophyll on top of the graphene and letting it evaporate, eventually coating the graphene with a layer of chlorophyll. When a voltage is established between the silver electrodes, relatively little current flows. But, when the chlorophyll interacts with the light of certain frequencies, the current increases dramatically. The light causes the chlorophyll to release electrons into the graphene, which increases the current that flows.
Chen notes that every photon the chlorophyll absorbs increases the current by about one million electrons.
From Technology Review
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