Light-Trapping and Interface Morphologies of Amorphous Silicon Solar Cells on Multiscale Surface Textured Substrates

The short circuit current and quantum efficiency of silicon thin-film solar cells can be increased by using multiscale surface textures consisting of micro- and nanoscale textures. Adding microtextures to the already existing nanosurface textures leads to an increase of the short circuit current from 15.5 mA/cm² to almost 17 mA/cm² for thin amorphous silicon solar cells. To gain insights into the light-trapping properties, finite difference time domain simulations were carried out using realistic interface morphologies. The simulations reveal that the gain of the short circuit current is caused by an increased effective thickness of the solar cell and the scattering properties of the microtextured back reflector. The thickness of the solar cells is increased by the growth of the silicon p-i-n diode on the microtextured surface. The influence of the nanoscale and multiscale surface textures on the quantum efficiency and short circuit current will be discussed.