Best of Both Worlds: Solar Hydrogen Production Breakthrough

Using a simple solar cell and a photo anode made of a metal oxide, HZB and TU Delft scientists have successfully stored nearly five percent of solar energy chemically in the form of hydrogen. This is a major feat as the design of the solar cell is much simpler than that of the high-efficiency triple-junction cells based on amorphous silicon or expensive III-V semiconductors that are traditionally used for this purpose. The photo anode, which is made from the metal oxide bismuth vanadate (BiVO4) to which a small amount of tungsten atoms was added, was sprayed onto a piece of conducting glass and coated with an inexpensive cobalt phosphate catalyst.

“Basically, we combined the best of both worlds,” explains Prof. Dr. Roel van de Krol, head of the HZB Institute for Solar Fuels: “We start with a chemically stable, low cost metal oxide, add a really good but simple silicon-based thin film solar cell, and — voilà — we’ve just created a cost-effective, highly stable, and highly efficient solar fuel device.”

Thus the experts were able to develop a rather elegant and simple system for using sunlight to split water into hydrogen and oxygen. This process, called artificial photosynthesis, allows solar energy to be stored in the form of hydrogen. The hydrogen can then be used as a fuel either directly or in the form of methane, or it can generate electricity in a fuel cell. One rough estimate shows the potential inherent in this technology: At a solar performance in Germany of roughly 600 Watts per square meter, 100 square meters of this type of system is theoretically capable of storing 3 kilowatt hours of energy in the form of hydrogen in just one single hour of sunshine. This energy could then be available at night or on cloudy days.

Written by Science Daily. To read the full article, click here.

Stanford Researchers Develop Record-Breaking Thinner Solar Cells That Absorb More Light

Solar power research is a big deal. Scientists have been searching for a way to improve photovoltaic efficacy for years by developing new technologies – from giant solar concentrator arrays to satellites that beam power back to Earth. Now, Stanford University researchers have developed what they call the thinnest, most efficient photovoltaic wafers ever. Instead of increasing the size of the solar arrays, the researchers created solar wafers with a nano-sized structure that is 1,000 times thinner than any other commercially available thin-film solar cell absorbers.

According to the researchers, the thin film solar wafers are only 1.6 nanometers thin, which cuts down on materials required to produce the cells while making them lighter. At the same time, all of this was done without comprising the solar cells’ ability to absorb visible light. These smaller photovoltaic cells can actually absorb parts of the visible light spectrum with incredible efficiency.

“The coated wafers absorbed 99 percent of the reddish-orange light,” Carl Hagglund, postdoctoral scholar at Department of Chemical Engineering and lead author on the study, said in a statement. “We also achieved 93 percent [light] absorption in the gold nanodots themselves.”

Written by Kevin Lee. To read the full article, click here.