Nanoparticle Breakthrough Can Make Higher Efficiency Solar Cells and Speed Development of Nanotechnology. Brian Wang at Next Big Future has the story of a classic case of serendipity in research.
The yellow is what the sun puts out that hits the top of the atmosphere (what a solar power satellite would see, for example). The red is what gets through to the ground. The green vertical bar represents a photovoltaic’s optimal response (but it actually has a tail that covers the visible range at a reduced efficiency). The blue bar is the tunable response area of the nanoparticles used as quantum dots — you have to make a lot of different sizes to cover the range.
Once we get real nanotech, of course, we’ll just make yagi antennas in the appropriate frequencies.