Solar cells tend to lose efficiency due to defects in the material of the cell itself. This causes negative electrons and positive holes to become trapped in the area, reducing performance.
Oak Ridge National Laboratory (ORNL) has developed a new solar cell that stops the entrapments effect, a nanocone-based cell. It is a 3D surface consisting of n-type nanocones of zinc oxide, and a p-type matrix made of polycrystalline cadmium telluride. The p-type absorbs the photons and conducts holes, while the n-type acts as a junction framework and conducts the electrons. Jun Xu, of ORNL, says " 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... The important concept behind our invention is that the nanocone shape generates a high electric field in the vicinity of the tip junction, effectively separating, injecting and collecting minority carriers, resulting in a higher efficiency than that of a conventional planar cell made with the same materials."
The result gives the new cell a light-to-power conversion efficiency of 3.2% over similar flat panel photovoltaic cells of the same material at their standard 1.8% efficiency. That is an achievement for silicone based solar cells, but is not that great compares to nanotube based cells or even the fringe magnetic light harvester. Efficiency boosts will affect the overall power generation industry nevertheless.
Eavesdropper
pic via Oak Ridge National Laboratory