Researchers have achieved record efficiencies in a promising group of photovoltaic materials. These materials – transition metal dichalcogenides – or TMDs – absorb ultrahigh levels of the sunlight that strikes their surface compared to other solar materials like silicon. It is much too heavy, bulky, and rigid for applications where flexibility, lightweight, and high power are preeminent, such as wearable devices, sensors, autonomous drones, and electric vehicles.
The new prototype achieves 5.1 percent power conversion efficiency. Still, the researchers could practically reach 27 percent efficiency (on par with the best solar panels on the market today, silicon included) upon optical and electrical optimizations.
The new solar materials possess remarkable thinness, which minimizes the material usage and cost and makes TMD solar cells lightweight and flexible. TMDs are moldable to irregular shapes – a car roof, an airplane wing, or the human body. The research team produced an active array that is just a few hundred nanometers thick. It includes the photovoltaic TMD tungsten diselenide and contacts of gold spanned by a layer of conducting graphene that is just a single atom thick, sandwiched between a flexible, skin-like polymer and an anti-reflective coating that improves the absorption of light.