Maximum light trapping for the random back-reflective silicon film solar cell with omnidirectional light transmission characteristics

The light trapping characteristics in the wavelength range of 0.5−1.2 μm for the random back-reflective silicon film with omnidirectional top anti-reflection are numerically analyzed based on the simplified probability method. The spectrum averaged maximum external quantum efficiency (EQE) for the 5 μm thick silicon film is evaluated with an increase of 10.6% compared with the best bulk planar silicon solar cell—suggesting that an efficiency higher than those of the best bulk planar cell can be obtained for thin film silicon solar cells several microns thick. The light absorption curves drop slowly with increased back absorption, exhibiting that the performance of the thin film silicon solar cell with light trapping is tolerant of back absorption.