An Investigation of Internal Quantum Efficiency of Bifacial Interdigitated Back Contact (IBC) Crystalline Silicon Solar Cell

In this article, we investigated the internal quantum efficiency (IQE) properties of n-type bifacial interdigitated back contact crystalline silicon solar cells using an IQE mapping system. In the cell structure, high and low IQE values were observed above the emitter and back surface field (BSF) regions. The IQE values above the BSF busbar were drastically reduced due to electrical shading loss. Line scan profiles at different wavelengths showed the detailed distribution of IQE values. The IQE values varied greatly depending not only on the difference between emitter and BSF regions but also on the rear side structure such as the electrode width and the distance between the emitter and BSF regions. On the other hand, the IQE spectra at over 950 nm improved by increasing the light absorbance ratio from the rear side. After module formation, the IQE spectra at short wavelengths were significantly reduced. The IQE properties were obtained from the front and rear sides. The difference in the short-circuit current between front side illumination and rear side illumination was mainly due to optical shading loss and carrier recombination loss at the BSF region. For a high cell efficiency, it is necessary to improve the passivation properties of the BSF region and optimize the electrode design.