Amorphous silicon sola cells on plastic based photonic structures

Thin film solar cells are an increasingly important technology for photovoltaic energy conversion. For Si based thin films, it is necessary to increase absorption path in order to absorb as many photons as possible. In this paper, we show how one can use a 2 dimensional photonic structure to diffract light and significantly enhance light absorption. The 2D photonic structure consists of precise cylindrical holes fabricated in a polymer using nano-imprint technology. The polymer is then coated with silver and ZnO, and a-Si:H solar cells, both single junction and tandem junction, are deposited on the photonic structure. Significant enhancement in current is obtained in both structures, and quantum efficiency measurements confirm that the photonic structure is giving rise to enhanced absorption in the film.