Solar energy: a revolution with graphene and molybdenite?

A group of researchers from the prestigious MIT has just published an article stating that by combining graphene with molybdenite, it could be possible to manufacture revolutionary solar cells, so thin that they would surpass all existing technologies. Research on devices capable of capturing solar energy using graphene has been particularly abundant lately. Some are trying to create phototransistors with this extraordinary material, but what is most exciting and would have the greatest impact on our lives is the possibility of making revolutionary photovoltaic cells out of it.

A group of researchers from the renowned MIT has just published in Nano Letters an article about a new type of graphene solar cells. At first glance, the performance is disappointing. The researchers' photovoltaic cell is significantly less efficient than standard cells, as the efficiency is only 1 to 2% for the graphene-based cell, compared to 15 to 20% for silicon ones.

Graphene and TMD, the miracle recipe

However, if we limit ourselves to these considerations, we would miss an important point. The thickness of the MIT researchers' cell is barely more than two atoms, as it consists of a stack of one graphene sheet and a second quasi-monoatomic sheet. This second sheet is made by combining a transition metal, such as molybdenum, with a dichalcogenide (a compound whose formula contains two ions with two negative charges, derived from elements in the 16th column of the periodic table such as oxygen, sulfur, or selenium). The material making up this second layer is therefore an example of what is called in English transition metal dichalcogenides (TMDs). A well-known TMD is molybdenite, which was presented some time ago as a competitor to graphene for making transistors.

This graphene and TMD cell is hundreds of thousands of times thinner than a conventional photovoltaic cell. At equal weight, solar sensors made from such cells are considerably more efficient than all current models. They would be particularly suitable for equipping airplanes, satellites, or space probes. Moreover, very resistant to UV, air, and humidity, they do not need to be covered with a glass layer. Finally, molybdenite is very abundant on Earth.

A record... for still theoretical photovoltaic cells

With such properties, it seems like a dream, and this fully justifies the label of miracle material for graphene. The solar energy revolution seems within reach, but indeed, for now, we are dreaming...

The MIT researchers' work is purely theoretical and is based only on calculations. Additionally, we do not yet know how to exfoliate molybdenite industrially. However, this last obstacle seems far from insurmountable. Nevertheless, there are many possible TMDs waiting to be explored in combination with graphene. Who can predict what nanotechnologies with these materials will yield in ten years?

Source: futura-sciences.com