Plastic solar cells based on inorganic nanorods and semiconducting polymers could make solar energy more affordable, according to scientists in the US (Science 295 2425).

The devices, developed by Wendy Huynh and colleagues at the Lawrence Berkeley National Laboratory, combine the affordability of plastic-based cells with the efficiency of semiconducting nanorod-shaped molecules. By adjusting the thickness of the rods, the energy range for absorbing incoming photons can be tuned.

The team's hybrid solar cells had a power conversion efficiency of 6.9%. Using CdSe nanorods measuring 7 nm by 60 nm to optimize the overlap of solar emission and cell absorption curve resulted in a 6.9% monochromatic conversion efficiency at 515 nm.

To improve on the devices, Huynh's team plans to reduce charge recombination by enhancing carrier mobilities. This could be achieved by improving the nanocrystal-polymer interface to remove nanorod traps, making the nanorods longer, and aligning them perpendicular to the substrate.