New material said to triple efficiency of organic solar cells

Created by a team from Princeton University, the material is known as a plasmonic cavity with subwavelength hole array, or PlaCSH. Consisting of five very thin layers, it is said to overcome the two primary challenges that cause solar cells to lose energy: light reflecting from the cell, and the inability to fully capture light. On top is the window layer made of extremely fine metal mesh, through which the sunlight first passes. Next is a layer of transparent plastic, followed by a layer of semiconductive material. This is topped by a layer of titanium oxide, with a layer of aluminum sitting at the bottom of the stack. The combined thickness of all five layers is just 230nm. This distance, along with the spacing and diameter of the holes in the mesh, is said to be shorter than the wavelength of the sunlight itself, allowing only 4% of the light to be reflected, and up to 96% to be absorbed. According to Chou, this translates into a 52% increase in efficiency over conventional organic solar cells when it comes to converting direct sunlight into electricity. PlaCSH is also said to be superior at capturing sunlight coming in at steep angles, however, upping its efficiency by a further 81%.