Generally, solar panels are made out of silicon, and there’s a lot of silicon used in them. The increasing demand of silicon led to a rise in its price. The new silicon nanowire solar cells consist of arrays of radial p-n junction nanowires where the darker outer shell is composed of n-type silicon, to which the electron acceptor phosphorous has been added, and the lighter inner core from p-type silicon, to which the electron donor boron has been added. Each individual nanowire in the array has a p-n junction and acts as a tiny photovoltaic cell.
Because they do not reflect light like the standard solar cells do, they have a much greater efficiency, because the absorption rate is very high. The wavelength of light is greater than the nanowire’s diameter, so the nanowire structure won’t reflect that light, but it will absorb it. This cancels the need for expensive anti-reflexive coatings by the cell’s intrinsic nature.
Silicon solar cells based on nanowires have much shorter p-n junctions that thin film solar cells. In the nanowire structure, photo-excited electrons and holes (carriers) travel very short distances before being collected by the electrodes. This results in a higher carrier-collection efficiency in the core-shell nanowire structure, and this advantage leads to a higher tolerance for material defects.
Gang Chen from Cambridge University has done research on this. However, the efficiency of photon capture in the nanowire structures, another very important factor, has not yet been determined. The nature of this nano-material allow the use of lower quality silicon, which significantly lowers the price of the final cell.