A theoretical analysis of the total internal quantum efficiency (IQE) of a flat-band p-n homo-junction silicon solar cell with back reflector using distributed Bragg reflectors to improve the light trapping is presented and contributions of different regions of the structure to IQEs are simulated. An optical model for the determination of generation profile of the cell is adopted and multiple light passes are considered and compared to previous single light pass approach. It is found that the spatial widths of the cell, the surface recombination velocities, the front surface transmittance and the back reflector have significant impacts on the IQEs. With two light passes and normal incident light, the simulation result shows the IQEs can be increased over the one pass value by 6.34% and with a 60 degrees light reflection angle, the IQEs can be further increased by 9.01% while assuming the reflectance at back structure closed to 100%. The effect on IQEs by back reflectance is more significant than that by front transmittance. Under multiple light passes simulation, up to 51 light trapping passes have been considered at wavelength range 900-1100 nm, the cell IQEs can be enhanced by about 26.98%. (C) 2009 Elsevier Ltd. All rights reserved.