We are unable to create thin and lightweight modules using silicon solar cells due to the property of this particular material. If we are still going down this path, the only way would be to shift to other solar cell technologies, like the research team at Stanford University that attempted to create a different solar panel using the transition metal dichalcogenide (TMD).
The advantage of TMD lies in its additional degree of insolation absorption compared to other solar technology. Koosha Nassiri Nazif, a doctoral scholar of electrical engineering at Stanford University, commented that TMD cells have a thickness that is 15 times less than that of traditional solar panels, making them an excellent component for UAVs.
TMD solar cell has a bright future, though it remains at the development phase right now, with a conversion efficiency of merely 2%, which is a major difference compared to silicon solar that is now approaching 30%. Electrical engineering professor Krishna Saraswat pointed out that silicon solar occupies 95% of the solar market, though cells that are lighter, capable of bending, and even more eco-friendly, are inevitable.
Stanford University has managed to establish a TMD solar cell prototype that has a 5.1% efficiency, and the research team is quite confident that the efficiency can exceed 27% after optical and mechanical optimization. The new cell prototype is 100 times higher in power-to-weight ratio, and emits 4.4W of power per gram, which makes it on par with other thin-film solar cells. The team estimates the theoretical limit of the cell to be 46W/g.
Other advantages of the TMD solar cell are the exceedingly light weight and flexibility, as well as the exclusion of toxic substances, and biocompatibility. TMD solar cell is not only eco-friendly, but also reduces the consumption and cost of materials, and can be produced into irregular shaped solar cells that are applied on the rooftop of vehicles, aircraft wings, and UAVs.
The TMD cell developed by Stanford University is less than 6µm in thickness, which equals the same thickness of ordinary paper after 15 layers of accumulation. The cell comprises of TMD tungsten diselenide, 0.34nm of conductive graphene, 135nm of metal contact, as well as the soft polymer and anti-reflective coating on the outer shell, which denotes a significantly complex manufacturing process. The transfer of an ultra-thin TMD layer onto flexible materials would often damage the TMD layer.
With that being said, the R&D for this cell is to prepare for the next generation renewable energy, and the team believes that power, flexible, and durable TMD cell is a new path for solar technology.
(Cover photo source: Stanford University)