Scientists Double Solar Cell Efficiency
Widespread solar energy use is hampered by the inherent lack of efficiency of solar cells. Generally, even the best silicon solar cells are only theoretically able to turn 31 percent of sunlight into electrical energy. The current practice of stacking semiconductor layers can boost the efficiency of solar cells to 40 percent, but the manufacturing cost is so high that these solar cells are only practical for military or space applications. However, researchers have now discovered a way to significantly reduce incoming light electron energy loss - a key contributor to the lack of efficiency in solar cells.
When incoming light enters solar cells, a large number of high-energy “hot” electrons are created. Unfortunately, these electrons lose their energy within a picosecond. Research at the National Renewable Energy Laboratory (NREL) in 2001 showed that incorporating nanoscale pieces of semiconducting material called quantum dots could slow this energy loss, and increase efficiency.
Current research at the University of Texas in Austin goes a step further in combining quantum dots with semiconducting wafers. This combination allows the theoretical maximum efficiency of a solar cell to jump to about 66 percent.
Although testing is just in its beginning stages, researchers point out that manufacturing these new solar cells could be relatively cost-effective. This is an important step in helping increase commercial use of solar energy.