News Article
QDs could change the face of solar cells
Lead sulphide quantum dots may be cheaper and brighter than current solar cells used outdoors
Are those flat, glassy solar panels on your neighbour’s roof the pinnacle of solar technology? Maybe not.
Researchers in the University of Toronto’s Edward S. Rogers Sr. Department of Electrical & Computer Engineering have designed and tested a new class of solar-sensitive nanoparticle that is said to outshine the current technology.
This new form of solid, stable light-sensitive nanoparticles, called colloidal quantum dots, could lead to cheaper and more flexible solar cells, as well as better gas sensors, infrared lasers, infrared LEDs and more.
The work, led by Zhijun Ning and Ted Sargent, was published this week in Nature Materials.
Co-authors Zhijun Ning (left) and Oleksandr Voznyy (right) examine a film coated with colloidal quantum dots (Credit: Roberta Baker)
Collecting sunlight using these tiny colloidal quantum dots depends on two types of semiconductors: n-type, which are rich in electrons; and p-type, which are poor in electrons. The problem? When exposed to air, n-type materials bind to oxygen atoms, give up their electrons, and turn into p-type.
Ning and his colleagues modelled and demonstrated a new colloidal quantum dot n-type material that does not bind to oxygen when exposed to air.
The main material used was PbS (lead sulphide), a IV-VI semiconductor.
Maintaining stable n- and p-type layers simultaneously not only boosts the efficiency of light absorption, but also opens up a world of new optoelectronic devices that capitalise on the best properties of both light and electricity.
This means more sophisticated weather satellites, remote controls, satellite communication or pollution detectors.
“This is a material innovation, that’s the first part, and with this new material we can build new device structures,” says Ning. “Iodide is almost a perfect ligand for these quantum solar cells with both high efficiency and air stability - no one has shown that before.”
Ning’s hybrid n- and p-type material achieved solar power conversion efficiency up to eight percent which they say is one of the best results reported to date.
But the researchers believe this improved performance is just a start for this new quantum-dot-based solar cell architecture. The QDs could be mixed into inks and painted or printed onto thin, flexible surfaces, such as roofing shingles, dramatically lowering the cost and accessibility of solar power for millions of people.
“The field of colloidal quantum dot photovoltaics requires continued improvement in absolute performance, or power conversion efficiency,” Sargent concludes. “The field has moved fast, and keeps moving fast, but we need to work toward bringing performance to commercially compelling levels.”
The study has been described in the paper, "Air-stable n-type colloidal quantum dot solids," by Zhijun Ning et al in Nature Materials (2014). doi:10.1038/nmat4007
This research was conducted in collaboration with Dalhousie University, King Abdullah University of Science and Technology and Huazhong University of Science and Technology.
Researchers in the University of Toronto’s Edward S. Rogers Sr. Department of Electrical & Computer Engineering have designed and tested a new class of solar-sensitive nanoparticle that is said to outshine the current technology.
This new form of solid, stable light-sensitive nanoparticles, called colloidal quantum dots, could lead to cheaper and more flexible solar cells, as well as better gas sensors, infrared lasers, infrared LEDs and more.
The work, led by Zhijun Ning and Ted Sargent, was published this week in Nature Materials.
Co-authors Zhijun Ning (left) and Oleksandr Voznyy (right) examine a film coated with colloidal quantum dots (Credit: Roberta Baker)
Collecting sunlight using these tiny colloidal quantum dots depends on two types of semiconductors: n-type, which are rich in electrons; and p-type, which are poor in electrons. The problem? When exposed to air, n-type materials bind to oxygen atoms, give up their electrons, and turn into p-type.
Ning and his colleagues modelled and demonstrated a new colloidal quantum dot n-type material that does not bind to oxygen when exposed to air.
The main material used was PbS (lead sulphide), a IV-VI semiconductor.
Maintaining stable n- and p-type layers simultaneously not only boosts the efficiency of light absorption, but also opens up a world of new optoelectronic devices that capitalise on the best properties of both light and electricity.
This means more sophisticated weather satellites, remote controls, satellite communication or pollution detectors.
“This is a material innovation, that’s the first part, and with this new material we can build new device structures,” says Ning. “Iodide is almost a perfect ligand for these quantum solar cells with both high efficiency and air stability - no one has shown that before.”
Ning’s hybrid n- and p-type material achieved solar power conversion efficiency up to eight percent which they say is one of the best results reported to date.
But the researchers believe this improved performance is just a start for this new quantum-dot-based solar cell architecture. The QDs could be mixed into inks and painted or printed onto thin, flexible surfaces, such as roofing shingles, dramatically lowering the cost and accessibility of solar power for millions of people.
“The field of colloidal quantum dot photovoltaics requires continued improvement in absolute performance, or power conversion efficiency,” Sargent concludes. “The field has moved fast, and keeps moving fast, but we need to work toward bringing performance to commercially compelling levels.”
The study has been described in the paper, "Air-stable n-type colloidal quantum dot solids," by Zhijun Ning et al in Nature Materials (2014). doi:10.1038/nmat4007
This research was conducted in collaboration with Dalhousie University, King Abdullah University of Science and Technology and Huazhong University of Science and Technology.
