High absorption enhancement of invert funnel and conical nanowire solar cells with forward scattering

Silicon nanowire solar cells with enhanced absorptions have been designed. Engineering of the nanowire shapes have been used to increase the light trapping. The absorption enhancement of the cylindrical, conical, invert conical, funnel and invert funnel shaped nanowires have been studied and compared. Simulation results revealed that the invert funnel shaped nanowires has the best light trapping capability. Forward (Mie) scatterers have been added to the solar cells in the ITO top contact. The ITO scatterers appear like hemispheres which protrude from the top contact. Each nanowire is equipped with one hemispherical Mie scatterer on its top. The absorptions, percentages of the absorption enhancement, short circuit currents and power conversion efficiencies for all the proposed nanowire arrays before and after adding ITO scatterers have been computed and compared. The sizes of the Mie hemispheres have been chosen so that the short circuit current would be maximum. A significant enhancement in the absorption of all the solar cells with different nanowire shapes were realized due to the forward scattering. Among all the studied structures, some nanowire designs could reach short circuit currents of more than of 32 mA/cm(2) more than 52% absorption enhancements with respect to the simple cylindrical nanowires and more than 18% power conversion efficiencies. The simulation findings give the experimental researchers guidance on how to optimize the nanostructures to further improve the solar cell performance.