Promotional image. Solar gets another boost. (via University of Totonto)
In the improvement of solar technology, it is all about the small details. Tiny increases in efficiency shrinking the size and price of each panel and making sure all the nooks are made absorbent and conductive for tiny photons and electrons.
An international team of researchers led by University of Toronto Engineering Professor Ted Sargent, have just made their CQD or colloidal quantum dot solar cell a tiny bit more efficient, furthering CQD research which has theoretically promised efficiencies of up to 42%.
The teams CQD is made of a type of nano sized semiconductors, which capture both visible and invisible wavelengths of a much wider range of the solar spectrum. The increase in efficiency is credited to a “hybrid passivation” scheme to patch electron traps associated with poor surface quality that impedes conduction. The process uses organic and inorganic chemistry to introduce chlorine atoms between the quantum dots and fill unreachable nooks that lead to electron traps. After the applying the chlorine atoms, they add organic ligands to bind the quantum dots even closer. All of this helps to increase the density of the CQD and absorb more light.
These efforts have resulted in an increase of 37% compared to previous CQDs. This brings the total efficiency to a new high of just 7%.
What makes CQDs much more enticing, apart from its theoretical potential, is the cheap manufacturing costs. The research has revealed that manufacturing processed could resemble those of newspapers, which print in mass quantities on flexible substrates at costs close to those of paint or ink.
The project is being funded in part by the King Abdulla University of Science and Technology (KAUST) in Thuwal, Saudi Arabia. KAUST researchers are responsible for developing a CQD multi-junction PV, which used a “graded recombination layer” to conduct electrons from the visible to the infrared layers.
Many collaborations are resulting in better and better solar cells, little by little. But the engrossing plot shared by all of them is their smaller and smaller costs and creative, sometimes tiny-sized but very notable innovations.