Scientists at the USA’s Dept. of Energy’s Oak Ridge National Laboratory have created a three-dimensional solar cell which could boost photovoltaic (PV) light-to-energy conversion rates by 80 percent.
Typically, when sunlight is strikes the surface of a solar panel and is absorbed by PV cells, some of the charge created by solar photons becomes trapped by natural flaws in the bulk materials that make up the layers of the cell, resulting in a loss of final electricity output.
Optimising the energy efficiency of these charges – negative electrons and positive "holes" – was the focus of the Oak Ridge team, led by Jun Xu, of ORNL’s Chemical Sciences Division.
“To solve the entrapment problems that reduce solar cell efficiency, we created a nanocone-based solar cell, invented methods to synthesize these cells and demonstrated improved charge collection efficiency,” Xu said.
Oak Ridge’s 3D solar cell uses zinc-oxide n-type nanocenes to serve a framework for conducting electrons. A p-type matrix of polycrystalline cadmium telluride – often used in thin-film solar panel manufacture – serves as the primary photon absorber medium and hole conductor.
With the new structure and materials, the new cell demonstrated a light-to-energy conversion efficiency rate of 3.2 percent, compared to 1.8 percent efficiency of a conventional two-dimensional solar cell structure.
“We designed the three-dimensional structure to provide an intrinsic electric field distribution that promotes efficient charge transport and high efficiency in converting energy from sunlight into electricity,” Xu said.
A world leader in solar energy research and development, Oak Ridge National Laboratory scientists are also working on a hybrid solar cell that harnesses the light-harvesting abilities of photosynthetic bacteria.
Unfortunately, Oak Ridge National Laboratory appears to have attracted some unwanted attention recently and last week shut down email and internet access after a virus designed to steal technical information successfully invaded its network.
