Nanostructured Compound Semiconductor Solar Cells

The efficiency to cost ratio of solar cells determines the price of solar generated electricity, and hence impacts the speed of up-take of solar cells by the society. The low-cost options currently available have low efficiencies and stability issues. On the other hand, stable and high efficiency products are expensive. A stable, low cost and high efficiency product is now required to encourage increased energy generation from renewable sources. Even more appealing is a flexible and light weight option that will enable integration of solar cells directly into buildings and accelerate the uptake of renewable energy sources. This project aims to demonstrate this much-needed product to fill-in the gap in the current solar cell market.

Compound semiconductors are inherently stable materials and hold the current record for the highest efficiency single junction solar cells under 1 Sun, AM1.5G illumination. However, the large volume of semiconductor material used in the conventional, wafer based architecture enormously increases the weight and costs associated with these devices, and makes functionalities like flexibility unthinkable.

This project will invoke non-conventional light absorption characteristics in compound semiconductor nanostructures to fabricate cheaper solar cells that use just a fraction of material used in the wafer based architecture, without compromising the efficiency. Nanostructuring enables control of the light-semiconductor interaction. Through proper design, light can be effectively localised/trapped in an absorber layer only a few nanometers thick until it is completely absorbed. The nanostructured compound semiconductor absorber can be grown directly on a cheap, flexible substrate or transferred to a flexible substrate, following growth on semiconductor wafers, enabling re-use the wafer for many more growths. This approach will make the devices flexible and cost-effective.