Light trapping in layer-transferred quasi-monocrystalline porous silicon solar cell

Quasi-monocrystalline porous silicon (QMPS) layers have a top surface like crystalline silicon with small voids in the body. Such layers are reported to have significantly higher absorption coefficient compared to crystalline silicon at the wavelength of interest for solar cells. A model has been developed to account for higher absorption coefficient of QMPS layer. The model conforms to the experimental results. The model is then extended to predict absorption coefficient of QMPS layer for different thickness, porosity and void size. Interesting results are obtained, particularly regarding the dependence of absorption coefficient on thickness and void diameter of QMPS layers. Computed values of absorption coefficient and some experimental results relating to electronic properties of QMPS layers are used to investigate the solar cell potential of QMPS layers. Short circuit current density of about 31 mA/cm2 is predicted for a QMPS layer of thickness 4 μm having average void radius of about 15 nm assuming effective diffusion length to be 5 μm.