Optimization of Band Gap and Thickness for the Development of Efficient n-i-p+ Solar Cell

By using an electrical-optical AMPS-1D program (One Dimensional Analysis of Microelectronic and Photonic structures), a n-i-p type solar cell, based on hydrogenated amorphous silicon (a-Si : H) and hydrogenated nanocrystalline silicon oxide (nc-SiOx : H) has been investigated and simulated. The numerical analysis describes the modeling of the external cell performances, like, the short-circuit current (JSC), the open circuit voltage (VOC), the fill factor (FF) and efficiency (Eff) with the oxygen content in the p-ncSiOx : H window layer by varying its mobility band gap (Eg) associated simultaneously to the effect of the absorber layer (i-a-Si : H) thickness. Also, the i-a-Si : H absorber layer band gap was optimized. The simulation result shows that the VOC depend strongly on the band offset (ΔEV) in valence band of p-side. But, VOC does not depend on the thickness of the intrinsic layer. However, VOC increases when the energy band gap of the intrinsic layer is higher. It is demonstrated that the highest efficiency of 10.44 % (JSC  11.67 mA/cm2; FF  0.829; VOC  1070 mV) has been obtained when values of p-nc-SiOx : H window layer band gap, i-a-Si : H absorber layer band gap and i-a-Si : H absorber layer thickness are 2.10 eV, 1.86 eV, and 550 nm, respectively.