Nanostructured silicon boosts thin-film PV

Thin-film photovoltaic (PV) cells made from amorphous silicon are low-cost, low-profile and suitable for many solar power applications. 

There’s been a barrier to the widespread use of thin-film PV technology, however: its low power-conversion efficiency compared to crystalline silicon cells. 

In cases where roof space is limited, for example, it is simply cost-effective for developers to pay for the higher power produced by crystalline silicon solar panels. 

But now researchers in Singapore claim to have developed a highly efficient thin-film silicon solar cell, which could cut the cost of solar energy in half.

Developed jointly by Nanyang Technological University (NTU) and A*Star Institute of Microelectronics (IME), the new thin-film solar cells are made from textured “nanostructured” silicon, thousands of times thinner than human hair.

This method allows manufacturers to use cheaper, low grade silicon, while still being able to generate electric current at levels close to that produced by solar cells made from higher quality silicon.

According to Navab Singh, senior scientist of IME’s NanoElectronics Program, IME’s surface texturing strategy achieves a record high short circuit current density of 34.3mA/cm2, compared to 40mA/cm2 in most crystalline silicon cells. 

The result is a power conversion efficiency of 5.26 percent. With bulk crystalline solar cells achieving efficiencies of around 20-25%, the technology still has a way to go.

But according to Singh, “it is conceivable that subsequent efforts to improve fill factor and open circuit voltage would boost the final [power conversion efficiency] of the silicon thin film solar cells greatly to match that of bulk [silicon] solar cells.”

Still, in order for this innovative manufacturing process to take off, it will have to compete with the falling price of crystalline silicon solar panels (expected to fall dramatically over the next few years), and other forms of more efficient thin-film technology like CIGS.

* Lauren Craig, EarthTechling