The Simultaneous Impacts of the p nc-SiOx:H Window Layer Band Gap and the Back Reflection on the Performances of a-Si:H Based Solar Cells

In this study we have presented an investigation, by using numerical simulation, the simultaneous impacts of the p nc-SiOx:H window layer band gap (E_g) and the back reflection (RB) on the photovoltaic performances of hydrogenated amorphous silicon (a-Si:H) solar cells. For simulation, we have used the AMPS-1D (One Dimensional Analysis of Microelectronic and Photonic structures) code. The modeling was carried out on two configurations of the studied cell, one without rear reflector (RB = 0) and the other with rear reflector (RB = 0.8). The simulated results showed that the best output parameters of the cell were obtained in the case of the structure with rear reflector and when the value of the p-window layer band gap lies in the range from 2.05 eV to 2.10 eV. On the one hand, the values of the band diagram discontinuities on the conduction band levels ΔE_C1 and ΔE_C2 and on the valence band levels ΔE_V1 (interface between the window layer and the buffer layer) and ΔE_V2 (interface between the buffer layer and the active layer) are investigated to better understand the efficiency (E_ff) variations as a function of the window layer E_g. On the other hand, it is also obtained that the spectral response (SR) is very sensitive to the window layer band gap variations in the wavelength range from 0.35 to 0.55 mm for both cases. However, the spectral response decreases with the increase of E_g. Finally, the solar cell spectral response has improved in the wavelength range from 0.55 to 0.7 mm, and the best efficiency value (E_ff = 11.43 %) was obtained in the case of the structure with rear reflector.