Graphene-chlorophyll Phototransistor Uses Plant Material to Gather Light

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Graphene and chlorophyll have similar 2D structure. Picture by AlexanderAlUS.

Graphene and chlorophyll have similar 2D structure. Picture by AlexanderAlUS.

Researchers from Taiwan have developed a new hybrid material made of chlorophyll and graphene, with potential for use as a phototransistor. This showed an efficiency comparable to other graphene-based devices and, potentially, opens the doors to many new applications.

What is Graphene?

Graphene is a relatively newly-discovered material, which shows great potential for applications in several technological fields. Most of its properties (mechanical, electrical and optical) are due to its characteristic 2D structure.

To widen its applications, science can also use graphene with other materials which have complementary properties; these are graphene-based hybrid materials.

About Chlorophyll

Chlorophyll is an organic molecule present in the leaves of vegetable species such as plants and algae, and is essential to the lives of the plants as it can capture the energy from sunlight.

The plants then use the energy to convert carbon dioxide (CO2) and water (H2O) into carbohydrates (energy source) in the process of photosynthesis.

Structure of chlorophyll A. Photo by JDSchmidt on Wikimedia Commons.

This is the structure of chlorophyll A. Photo by JDSchmidt

Chlorophyll can have different forms, one of them (A form) is shown in the picture on the side.

Many researchers are currently performing research in an attempt to use chlorophyll for energy generation, considering its capacity to absorb energy from light (photoreceptor behavior).

New Hybrid Material: Chlorophyll and Graphene

Although graphene shows very high electron mobility, and consequently electrical conductivity, it is not a very good photoreceptor. Therefore, for effective use as a phototransistor, scientists must combine it with materials/compounds which are more effective in capturing the sun’s energy.

On this basis, researchers from Academia Sinica of Taiwan developed a new material made from a combination of chlorophyll and graphene. They performed their work in cooperation with the National Taiwan University of Taiwan, and published the results in arXiv on the 14th of June 2013; the journal “Carbon” has also accepted the research for publication.

Dr. Hei-Hua Wang, leading researcher of this study, tells Decoded Science:

In our hybrid material, the chlorophyll absorbs the light from the sun and converts it into energy; the graphene, on the other hand, can transport the electric charges generated by the illumination.

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