Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering at MIT, says the new approach "pushes towards the ultimate power conversion possible from a material" for solar power.
is the senior author of a new paper describing this approach, published in the journal Nano Letters
Although scientists have devoted considerable attention in recent years to the potential of two-dimensional materials such as graphene, Grossman
says, there has been little study of their potential for solar applications.
It turns out, he
says, "they're not only OK, but it's amazing how well they do."
team found that an effective solar cell could be made from a stack of two one-molecule-thick materials: Graphene (a one-atom-thick sheet of carbon atoms, shown at bottom in blue) and molybdenum disulfide (above, with molybdenum atoms shown in red and sulfur in yellow).
The two sheets together are thousands of times thinner than conventional silicon solar cells.
Graphic: Jeffrey Grossman
and Marco Bernardi
Using two layers of such atom-thick materials, Grossman
team has predicted solar cells with 1 to 2 percent efficiency in converting sunlight to electricity, That's low compared to the 15 to 20 percent efficiency of standard silicon solar cells, he
says, but it's achieved using material that is thousands of times thinner and lighter than tissue paper.
At about one nanometer (billionth of a meter) in thickness, "It's 20 to 50 times thinner than the thinnest solar cell that can be made today," Grossman
team's work so far to demonstrate the potential of atom-thick materials for solar generation is "just the start," Grossman
For one thing, molybdenum disulfide and molybdenum diselenide, the materials used in this work, are just two of many 2-D materials whose potential could be studied, to say nothing of different combinations of materials sandwiched together.
"There's a whole zoo of these materials that can be explored," Grossman
"My hope is that this work sets the stage for people to think about these materials in a new way."
While no large-scale methods of producing molybdenum disulfide and molybdenum diselenide exist at this point, this is an active area of research.
Manufacturability is "an essential question," Grossman
says, "but I think it's a solvable problem."
An additional advantage of such materials is their long-term stability, even in open air; other solar-cell materials must be protected under heavy and expensive layers of glass.
"It's essentially stable in air, under ultraviolet light, and in moisture," Grossman
"It's very robust."
The work so far has been based on computer modeling of the materials, Grossman
says, adding that his
group is now trying to produce such devices.
"I think this is the tip of the iceberg in terms of utilizing 2-D materials for clean energy" he