Quantum Dots may one day lead to a Doubling of Solar Cell Efficiency. Popular Mechanics has an interesting articular about how new research by the Department of Energy shows that Quantum Dots can double the efficiency of solar cells. Researchers have shown that it's possible to harvest lost energy before it escapes from standard inefficient solar cells in the form of heat, meaning that engineers could one day develop next-generation solar cells with efficiencies of up to 66 percent. The research, funded by the Department of Energy, is described in the June 18 edition of the journal Science.
Study author Xiaoyang Zhu at University of Texas at Austin said the group used nanoscale crystals of a compound called lead selenide which is a semiconductor, meaning it absorbs light energy within a certain range of energies. But semiconducting nanocrystals, also known as quantum dots, exhibit very different properties than their larger silicon counterparts. Most importantly they can hold on to a hot electron for a longer period of time, stretching out the amount of time it takes for the electron to cool instead of losing them to heat.
Once a hot electron is confined within a quantum dot the researchers chose titanium oxide, a well-studied compound known for its ability to accept new electrons to pull the electron out from the dot. Then the team arranging the lead selenide quantum dots and titanium dioxide in such a way that their chemical interactions would induce electron transfer.
Not only was the transfer successful, it was also very fast. However, the process is very difficult to accomplish meaning a long road for commercialization.
More details at Popular Mechanics.