Light trapping in a 30-nm organic photovoltaic cell for efficient   carrier collection and light absorption
  We describe surface patterning strategies that permit high photon-collection efficiency together with high carrier-collection efficiency in an ultra-thin planar heterojunction organic photovoltaic cell. Optimized designs reach up to 50% photon collection efficiency in a P3HT layer of only 30 nm, representing a 3- to 5-fold improvement over an unpatterned cell of the same thickness. We compare the enhancement of light confinement in the active layer with an ITO top layer for TE and TM polarized light, and demonstrate that the light absorption can increase by a factor of 2 due to a gap-plasmon mode in the active layer. 
Cheng-Chia Tsai, Richard R. Grote, Ashish Banerjee, Richard M. Osgood   Jr., Dirk Englund
physics.optics