Enhanced light absorption in the organic thin films by coating cross-shaped metamaterial resonators onto the active layers

Abstract

Cross-shaped resonators were proposed to improve the light absorption in the organic active layers, namely P3HT, PCBM and P3HT:PCBM hetero-structure. The resonator was made of aluminium (Al) which was encrusted on top of the organic active layers backed with indium tin oxide (ITO) coated glass. Simulated results showed that the proposed structure had significantly enhanced the light absorption in the organic thin films, whereby exhibited a broadband absorption in the visible and infrared spectra. An obvious redshift in the characteristic absorption peak of the organic thin films was observed, resulting in the reduction of their apparent energy gap due to the coupling effect between cross-shaped resonator and organic active layer as a consequence of light-matter interaction. It is concluded that the proposed metamaterial structure is beneficial to improve the performance of organic solar cells. Keywords: Metamaterial, Organic thin film, Light absorption, Cross resonator, Solar cell