Scientists are exploring 2D materials like TMDCs for ultra-thin, efficient solar cells. This breakthrough 2D material solar technology could power urban buildings.
The current landscape of 2D material solar technology
The new frontier of integrated photovoltaics? Transition metal dichalcogenides (TMDCs), two-dimensional materials that could one day replace silicon and other semiconductors in high-efficiency solar cells.
Research is still in its early stages, but a group of scientists at the Solar Energy Institute of the Polytechnic University of Madrid (UPM) is working on these 2D materials to turn promises into reality for 2D material solar technology.
Specifically, the team has developed ultra-thin solar cell micro-prototypes based on tungsten diselenide (WSe2) or molybdenum disulfide (MoS2), two of the most studied TMDCs. As van der Waals materials, these semiconductors maintain mechanical stability down to a monolayer thickness, while also absorbing a significant portion of incident light. What’s more, they are composed of elements abundant in the Earth’s crust and are extremely easy to produce.
Their strengths? In photovoltaics, they act as a kind of ultra-thin, smart filter, using the necessary light and allowing the rest to pass through. In other words, MoS2 and WSe2 solar cells are transparent due to the infinitesimal thickness of the semiconductor, while still ensuring efficiencies between 13% and 25%.
The drawback? Unlike silicon, when light strikes the material, it forms an exciton (an electron and a hole still bound together) that needs to be “broken.” But the real challenge is achieving precise thickness control down to a single monolayer, a goal currently impossible to reach with economically viable large-scale production methods.
The Spanish team achieved its microcells using a technique called hot-pick-up, where fragments of the materials are selected, collected, and deposited inside a transparent bubble, forming layered heterostructures optimized for specific experimental needs. The versatility of the process has allowed experimentation with different materials that, by combining their unique properties, enable optimal solar energy absorption. “By using this technique,” the university website states, “the group has achieved efficiency levels that place UPM among the leading universities in this technology.”
Today, scientists are working on new techniques to scale up the production process for 2D material solar technology from solution onto large surfaces. “Through spray coating techniques and the deposition of such solutions, it would be possible to scale up production processes, reducing costs and enabling the industrialization of this breakthrough photovoltaic technology,” researchers explain.
Potential applications of 2D material solar technology
In parallel, the real impact that the integration of this technology would have in urban centers was analyzed. By simulating the effects of cladding a skyscraper in Madrid with these materials in a semi-transparent configuration, it was estimated that up to 33% of the building’s energy needs could be covered. This value can be achieved while maintaining optimal lighting conditions inside the building, with a high color rendering index, an adequate annular temperature transition index, and acceptable brightness values.
