Influence of Defect States and Thickness of Interface Layer On High Efficiency of c-Si/a-Si:H Heterojunction Solar Cells With Higher Bandgap a-Si:H(p) Layer By Simulation

Abstract

This paper presents the influence of defect states and thickness of interface layer on high efficiency of c-Si/a-Si:H heterojunction solar cells with higher bandgap emitter a-Si:H(p) layer by AFORSHET simulation tool. At first, the performance of Ag/ZnO/a-Si:H(p)/ a-Si:H(i)/ c-Si(n)/ a-Si:H(i)/ a-Si:H(n)/Ag heterojunction solar cells was studied by altering the thickness of a-Si:H(p) and a-Si:H(i) layers. The best values of open circuit voltage (Voc) (764.8 mV), short circuit current density (Jsc) (43.15 mA/cm2), fill factor (FF) (85.71) and efficiency(ɳ) (28.28%) were obtained at 3 nm of a-Si:H(p) and a-Si:H(i) layer. In the same structure, c-Si(n) interface was introduced in between c-Si(n) and a-Si:H(i) layer. It is found that the solar cell performance was not changed by varying defect density from 109-1014 cm-3 for thin (5 and 10 nm) interface layer and estimated values are 761.7 mV, 38.83 mA/cm2, 86.09%, 25.46% correspond to Voc, Jsc, FF, ɳ respectively. For very thick interface layer, defect density has shown huge impact on the device performance. At 1 µm, the Voc, FF and ɳ values have been changed from 760.2 to 653.2 mV, 85.9 to 80.76% and 22.94 to 18.47% for the defect density of 109 to 1014 cm-3 respectively.