Quantifying the plasmonic orthogonalisation of light for Si, a-Si, and perovskite solar cells

The orthogonalisation of light is realized by placing a plasmonic nanostructure on a metal plate, which generates a plasmon resonance upon illumination. The plasmon resonance in the plasmonic nanostructure generates surface plasmon polaritons (SPPs) on the metal surface. These SPPs can transfer their energy to semiconductors on top, which could increase the efficiency of solar cells. In this work, such a system has been explored by finite difference time domain simulations for silver nanoparticles on a silver plate with Si, a-Si and perovskite thin layers on top. It was found that the SPPs generated by the silver nanoparticle can only transfer their energy to the semiconductor on top if the plasmon resonance energy matches with the semiconductor band gap. This constraint was lifted when a plasmonic nanoparticle was placed outside the illuminated area; it functioned as an antenna, converting the SPP energy back into light, increasing the optical absorption strongly. This information is important for the design of future nanostructured thin film solar cells which want to employ orthogonalisation to increase the solar energy conversion efficiency. (paper)