STANFORD UNIVERSITY, CALIFORIA, USA. Nanocones are hybrid solar cells that can minimize the required amount of silicon materials and improves light absorption. These attributes make nanocones very cost-effective and at the same time provide exemplary performance.

The silicon photovoltaic industry is still concerned with the high production cost of solar cells. Currently, the module cost is $1/watt. In order to come up with inexpensive solar cells, the module cost must be lowered half its original cost. The cost of the silicon materials and its fabrication cost attributed to the current expensive cost of solar cells.

Stanford University’s Professor Michael D. McGehee and Professor Yi Cui made a research on the use of nano structuring. Prior research on nanoscale texturing of solar cells included nanodomes, nanowires and other configurations. In their study, they found out that height and diameter of a nanocone with an aspect ratio of 1 can provide an optimal shape for light absorption enhancement because it allows light scattering (long wavelengths of light) and good anti-reflection (short wavelengths of light). The research has proven that there is a reduction in the require silicon materials. Also, it absolutely enhanced light absorption.

In previous designs using nanoscale texturing, the space between structures has normally been too small to be filled with polymer, so a full second layer is required. But the tapered nanocone structure demonstrated here allows for the polymer to be coated in the open spaces, eliminating the need for other materials. By forming this nanocone/polymer hybrid structure with a simple, low-temperature method, processing costs are also reduced.

Former designs of solar cells that utilized nanoscale texturing have small spaces between structures that are difficult to be filled with polymer. In this case, there is a need for a full second layer. On the other hand, the nanocone structure allowed the coating in the open spaces. This alone has removed the need for additional materials. Also, the process for the nanocone requires a simple and low-temperature method that can immensely reduce the processing costs.

Further improvements and tests resulted to an efficiency of 11.1%. This is already the highest among organic solar cells and hybrid silicons. Its short-circuit current density is slightly lower than the world record for a mono crystalline silicon solar cell. Its optimized performance combined with its affordable processing can absolutely benefit the silicon photovoltaic industry and the masses.