Tiny particles pack a lot of power

Scientists at the Nanyang Technological University (NTU) and the Singapore-Berkeley Research Initiative for Sustainable Energy are looking into how tiny particles can unlock major success in the solar industry.

They are zooming into the quantum structure of a material known as perovskite, studying nanoparticles that measure just a few nanometres in length - about 10,000 times smaller than the breadth of a strand of human hair.

They found that when perovskite nanoparticles are exposed to light, each particle captures more light energy for conversion into electricity.

In comparison, a lot of this energy is lost through heat in conventional solar cells made of silicon.

These findings were published earlier this year in science journal Nature Communications.

One of the researchers who made the discovery, Associate Professor Sum Tze Chien, said: "Normal silicon solar cells waste a lot of energy through heat since they cannot convert the captured high-energy light into electricity.

"But much higher conversion efficiencies can be achieved if these high-energy 'hot' carriers can be converted to electricity."

Prof Sum, who is associate dean for research at NTU's College of Science, added that this discovery could pave the way for the development of hot carrier perovskite solar cells, which in theory could have efficiencies of up to 66 per cent.

This figure far outstrips the efficiencies of conventional land-based silicon solar cells, the highest of which is 25 per cent.

It also surpasses the more expensive solar cells used in space which have an efficiency of 28 per cent.

However, Prof Sum noted that much more research has to be done in this area before the technology becomes commercially available.

"The huge theoretical efficiency means we have a lot of room for improvement, and one of our main goals is to make perovskites generate more electricity with the same surface area as silicon solar cells, but at a much lower cost," he added.

The team also discovered that other than absorbing energy for conversion into electricity, perovskite nanoparticles could also emit light. This allows for the potential application where a perovskite screen could function as both a display screen and solar panel, said the scientists.

Professor Subodh Mhaisalkar, executive director of NTU's Energy Research Institute, said: "So, for instance, you could have the screen function as a solar panel in the day and, at night, it could double as a signboard or billboard. Developing solar technology that is better yet greener is a huge challenge, but perovskite is proving to be a very capable material, having demonstrated excellent properties for both harvesting and emitting light."

Audrey Tan

A version of this article appeared in the print edition of The Straits Times on June 02, 2017, with the headline 'Tiny particles pack a lot of power'. Print Edition | Subscribe