Improving the heterojunction silicon solar cell efficiency by using GaP intrinsic layer

In this article, the operations of heterojunction silicon solar cells were investigated theoretically. The studied structure is TCO/ a-SiC (P)/ GaP (i)/ a-Si (n)/ a-Si (n)/ metal. In this study instead of using conventional structure, which uses an amorphous intrinsic layer, a GaP (Gallium Phosphate) layer is used as intrinsic buffer layer. Different models of this solar cell structure were simulated. The effect of various parameters such as work functions of front and back contacts, emitter and n-type amorous silicon layer carrier densities, emitter band gap, GaP buffer layer thickness, current- voltage curves and quantum efficiency has been studied. The optimum values for above mentioned quantities are presented based on the study results. Moreover the band structure of different cases is plotted. The results show that using a GaP intrinsic layer with 2.26 ev band gap and 1 micrometer thick, leads to the highest efficiency around 21.13% with Voc=1.52 V, Jsc=16.58 mA.cm-2 and FF= 84 %.