“TiO2CdS” is chemist shorthand
for a mixture of titanium dioxide and cadmium sulphide, neither of which you would want on your morning toast, but titanium dioxide used to be in some toothpastes and cadmium was once used to coat refrigerator shelves. Titanium dioxide is still used in paint today and makes the whitest white available.
Soon, the combination may coat your roof while supplying electricity to your home. A team of scientists at Notre Dame University has published a paper on how to use the chemistry in paint that can also double as solar electric collector.
What goes unsaid in the abstract for the paper is what kind of efficiency to expect from the new paint or what the expected cost will be. The full paper may have that info and I will be soliciting the article through my library, but I refuse to pay for a subscription to any publication that has only one or two truly interesting articles per year. Let me get off my high horse here and get back to the topic.
The TiO2CdS technology is an ingenious combination of nano-scale assembly and quantum laser generating optics. It’s described as “quantum dot solar cells”. In simplest terms, sunlight pumps energy into it and electricity comes out, much like in a more typical silicon solar cell, but, again, this is in the form of a paint that can be applied to almost any solid surface.
While neither CdS nor TiO2 cells are new, the combination is new and allows a wider absorption spectrum and therefore greater efficiency than either chemistry alone, although I still don’t know what efficiency the team predicts. Based on my own work in these fields, 4% efficiency would be a good benchmark. So if your three bedroom ranch style home in North Georgia were oriented with the gables east and west and the paint’s efficiency hits that benchmark, you could expect your roof to generate about 8 to 10kW at noon on a very clear day in late June.
However, on a equally clear Christmas Day, its output will be down by a third or so and even that is assuming there’s no snow on the roof. Reindeer and a sleigh on the roof might introduce different factors into the energy equation.