Paper Pitch: More efficient solar cells
Did you know that solar cells typically convert only 20% of the sunlight into electrical power? That means that 80% is not utilised, leaving large room for improvement for next generation solar cells. Researchers from Delft University of Technology developed a method to find new materials for more efficient solar cells.
This video was made possible with help from Jos Thieme, laser technician.
“When sunlight hits a solar cell, it sets electrons in motion. This current can then be used to power electrical devices. Solar cells are made of semiconductors which have a property that is called a ‘band gap’. The band gap describes the minimum amount of energy required for sunlight to be absorbed by the solar cell. If the light does not have enough energy, like infrared light, it will pass straight through the absorber layer of the solar cell.
UV light on the other hand has much more energy than the band gap and can be absorbed by the solar cell. But when this happens, the electrons that are set in motion rapidly bump into the atoms of the solar cell, and lose most of their energy in the form of heat. The excess energy from UV light thus cannot be converted into electricity.
More current
In some materials however, a process called ‘charge carrier multiplication’ occurs, making them more efficient. In this process, the electrons that were set in motion by UV light bump into other electrons rather than into the atoms of the solar cells. The result is that the excess energy is no longer lost as heat, but is used instead to mobilise more electrons. And so we can get more electrical current from the same amount of light!
Screening materials
To find more efficient materials with carrier multiplication, we first need to make them in the lab and then extensively test them with special equipment. This is a time consuming and costly process. In our article, we present a method to model carrier multiplication with computer calculations. We can apply this method to screen new materials for carrier multiplication efficiency before we actually make them in the lab. This saves the costs and efforts that would be required to make and experimentally test all kinds of materials.”
— Sven Weerdenburg
Sven Weerdenburg conducted this research project during his Masters’ thesis at the Opto-electronics Materials section at the department of Chemical Engineering (Faculty of Applied Sciences). He currently pursues a PhD at the Catalysis Engineering section of the same department.
