Media Releases

New class of nanoparticle brings cheaper, lighter solar cells outdoors

June 9, 2014

TORONTO, ON — Think those flat, glassy solar pan­els on your neighbour’s roof are the pin­na­cle of solar tech­nol­o­gy? Think again.

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 out­shines the cur­rent state of the art employ­ing this new class of 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 light emit­ting diodes and more. The work, led by post-doc­tor­al researcher Zhi­jun Ning and Pro­fes­sor Ted Sar­gent, was pub­lished this week in Nature Mate­ri­als.

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 the air, n‑type mate­ri­als bind to oxy­gen atoms, give up their elec­trons, and turn into p‑type. Ning and col­leagues mod­elled and demon­strat­ed a new col­loidal quan­tum dot n‑type mate­r­i­al that does not bind oxy­gen when exposed to air.

Main­tain­ing sta­ble n- and p‑type lay­ers simul­ta­ne­ous­ly not only boosts the effi­cien­cy of light absorp­tion, it opens up a world of new opto­elec­tron­ic devices that cap­i­tal­ize on the best prop­er­ties of both light and elec­tric­i­ty. For the aver­age per­son, this means more sophis­ti­cat­ed weath­er satel­lites, remote con­trollers, 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,” said 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 new hybrid n- and p‑type mate­r­i­al achieved solar pow­er con­ver­sion effi­cien­cy up to eight per cent—among the best results report­ed to date.

But improved per­for­mance is just a start for this new quan­tum-dot-based solar cell archi­tec­ture. The pow­er­ful lit­tle dots 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,” said Sar­gent. “The field has moved fast, and keeps mov­ing fast, but we need to work toward bring­ing per­for­mance to com­mer­cial­ly com­pelling lev­els.”

This research was con­duct­ed in col­lab­o­ra­tion with Dal­housie Uni­ver­si­ty, King Abdul­lah Uni­ver­si­ty of Sci­ence and Tech­nol­o­gy and Huazhong Uni­ver­si­ty of Sci­ence and Tech­nol­o­gy.


Media con­tact:
Mar­it Mitchell
Senior Com­mu­ni­ca­tions Offi­cer
The Edward S. Rogers Sr. Depart­ment of Elec­tri­cal & Com­put­er Engi­neer­ing
Uni­ver­si­ty of Toron­to