IR-sensitive nanomaterial could lead to 30%-efficiency solar cell

January 14, 2005, Toronto, Canada--Researchers at the University of Toronto (U of T) have invented an infrared-sensitive nanomaterial that is reported to be the world's first solution-processed photovoltaic in the infrared.

In a paper to be published on the Nature Materials website on January 9, senior author Professor Ted Sargent, Nortel Networks--Canada Research Chair in Emerging Technologies at U of T's Department of Electrical and Computer Engineering, and his team report on their achievement in tailoring matter to harvest the sun's invisible rays. "We made particles from semiconductor crystals which were exactly two, three or four nanometres in size. The nanoparticles were so small they remained dispersed in everyday solvents just like the particles in paint," he explains. Then, they tuned the tiny nanocrystals to catch light at very long wavelengths. The result � a sprayable infrared detector.

Professor Peter Peumans of Stanford University, who has reviewed the U of T team's research, also acknowledges the groundbreaking nature of the work. "Our calculations show that, with further improvements in efficiency, combining infrared and visible photovoltaics could allow up to 30 per cent of the sun's radiant energy to be harnessed, compared to six per cent in today's best plastic solar cells."

U of T electrical and computer engineering graduate student Steve MacDonald carried out many of the experiments that produced the world's first solution-processed photovoltaic in the infrared. "The key was finding the right molecules to wrap around our nanoparticles," he explains. "Too long and the particles couldn't deliver their electrical energy to our circuit; too short, and they clumped up, losing their nanoscale properties. It turned out that one nanometer � eight carbon atoms strung together in a chain � was 'just right'."