However, Harry Atwater and his colleagues argue in Nano Letters that cleverly made thin layers could help solar cells to overcome the ray-optic limit2. When the layers have thicknesses below the wavelength of visible light — 400–700 nanometres — they interact with its wave properties rather than treating it as a straight ray. “In this regime, where the structures we make are at or below the scale of the wavelength of light, suddenly all the rules change,” says Atwater. In this case, rather than depending on thickness, a material’s ability to absorb light depends on the wave interactions between the light and the absorber.
Picosun concludes that ROD-SOL’s novel silicon nanorod cell concept shows promising potential for increasing the efficiencies of thin film solar cells and reducing manufacturing costs. As might be expected, the Finnish company is “especially satisfied” that their ALD played a central role in making this happen. “The next step for us will definitely be [to continue] developing ALD technology and equipment for solar energy applications,” says Minna Toivola, who coordinated the ROD-SOL project on Picosun’s end. “ALD for Si solar cell passivation—which can increase the cell efficiency [by] 1-2% and is, in many ways, [a] better method than what has been “traditionally” used [for] this purpose—, for example, has evoked a lot of interest recently in the global PV community.” The technology used in ROD-SOL to create the more efficient thin-film solar cells is still very new and might require some time and further development to go commercial. “But, the promising over 9% efficiencies and good long-term stability achieved already in this three-year project really make this technology worth of further investigation and hopefully we can see the first Si nanorod cells available to consumers in already a few years,” Toivola says.
Funded through the European Union Seventh Framework Programme (FP7), this project— dubbed ROD-SOL—led to energy conversion efficiencies of greater than 9%, with good long-term cell stability. The new silicon nanorod-based concept requires significantly less active photovoltaic material by growing light-trapping nanorod “forests” (thickness from
Under the agreements, California-based SunPower will engineer and construct the plant on the Mesa, Arizona campus, and will operate and maintain it. SRP, the public power utility, will buy the output of the solar plant from SunPower, and ASU will purchase the energy for use at its Polytechnic campus. Construction of the plant is contingent on a number of factors, including receipt of all applicable permits.
The company’s products are made with copper, indium,
gallium, and selenium instead of silicon that’s used in
conventional solar cells. AQT says its manufacturing is more
efficient than competitors because it uses equipment used in the
computer hard disk drive industry.
Picosun Oy, a global Atomic Layer Deposition (ALD) equipment manufacturer based in Finland, reported the final results of a multinational three-year research project aimed at pioneering nanomaterials that would make thin-film solar cells much more efficient and cheaper to manufacture.