Solution-based Manufacturing Technologies Show Promise for Cheaper, More Efficient Solar Cells
The solution-based manufacturing process being commercialized by Natcore was developed at Rice University deposits a passivating anti-reflection coating in a low-temperature, liquid phase deposition process rather than the high-temperature gas-based process typically used now. Due to the difficulty of producing a uniform coating for solar cells, manufacturers do not use liquid-based processes for antireflection coatings. The desired coating is difficult to achieve due to the way it forms in a liquid process; as reactants are expended during the interaction with a surface, deposition rates fluctuate and produce a nonuniform coating. By restocking the reactants and observing film thickness, Rice researchers were able to produce a uniform coating. The high-temperature processes used on a standard manufacturing line can be replaced by the liquid-based process, lowering manufacturing costs, including annual electricity costs, while providing a path to sustainable, large area production and scaling.
Natcore is simultaneously developing more advanced applications of the process, including fabrication of solar cells made of carbon nanotubes or nanoscale crystals called quantum dots. Future solar cells manufactured using these nanomaterials could far outperform conventional solar cells. As an example of one of Natcore's advanced nanomaterial solar cell designs, layers of quantum dots are deposited on a silicon solar cell. The quantum dots are designed to absorb colors that silicon is transparent to, potentially doubling the solar cell efficiency. While this has been tried before, the challenge is to achieve optimal dispersion and spacing of the quantum dots in a low cost, scalable process. The low cost Natcore process coats quantum dots with a silicon dioxide layer, acting as a spacer and allowing for control over their arrangement. To encourage industry adoption, Natcore is coating conventional silicon solar cells, but in the future may move completely to a quantum dot based solar cell. This model would use multiple types of quantum dots to efficiently absorb sunlight wavelengths.
Reference: Bullis K. 2012. New manufacturing tech could mean cheaper solar cells. technology review