On the interplay of cell thickness and optimum period of silicon thin-film solar cells: light trapping and plasmonic losses

Light trapping and photon management in honeycomb-textured microcrystalline silicon solar cells are investigated experimentally and by modeling of the manufacturing process and the optical wave propagation. The solar cells on honeycomb-textured substrates exhibit short circuit current densities exceeding 30mA/cm(2) and energy conversion efficiencies of up to 11.0%. By controlling the fabrication process, the period and height of the honeycomb-textured substrates are varied. The influence of the honeycomb substrate morphology on the interfaces of the individual solar cell layers and the quantum efficiency is determined. The optical wave propagation is calculated using 3D finite difference time domain simulations. A very good agreement between the optical simulation and experimental results is obtained. Strategies are discussed on how to increase the short circuit current density beyond 30mA/cm(2). In particular, the influence of plasmonic losses of the textured silver (Ag) reflector on the short circuit current and quantum efficiency of the solar cell is discussed. Finally, solar cell structures with reduced plasmonic losses are proposed. Copyright (c) 2015 John Wiley & Sons, Ltd.