Talking about selenide and other materials as a type of nanotech is kind of curious to me. I thought nanotechnology would be in the form of molecular machines that perform functions at the molecular level. This just looks like chemicals interacting with other materials. How soon do you think research will actually produce molecular machines that will be used in the workplace, whether it be engineering or some other field. -wi

I'm not sure I buy this. Neither gallium selenide nor indium selenide would be inexpensive materials on which to base bulk solar cells. In addition, one doesn't want to throw away the IR photons, one simply wants to stack them so the lower voltages add to the higher voltages provided by the visible photons. This is the basis behind thermophotovoltaic cells that are now being stacked with normal visible cells. The efficiencies claimed for these cells can be very high (over 35-40+%). To get higher efficiencies one needs to have a better strategy for doing something useful with the UV photons. They have the highest energy but have the nasty property of being able to break covalent bonds contributing to the degradation of the solar cells.