An Investigating on Impact of Absorbers’ Band Gap Variation on Performance of the New CIGS Solar Cell Structure Considering the Defect Density Model

A new CIGS solar cell structure, consisted of two absorber layer, is introduced in this paper. One of theabsorbers (next to the Mo back contact) has a graded band gap, and the other (next to the CdS buffer layer) hasconstant band gap energy. The band gap energies of the absorber layers are optimized in order to provide maximum efficiency for the solar cell. However, the Ga composition, which determines the band gap of the CIGS material, has a direct influence on the trap density. Therefore, a trap density model is interpolated based on the information reported in literatures. Since deep trap centers have significant impact on performance of solar cell, this model is applied to all simulations. The proposed method improves solar cell efficiency up to 20.4482%.

An Investigating on Impact of Absorbers’ Band Gap Variation on Performance of the New CIGS Solar Cell Structure Considering the Defect Density Model Keywords:

bi-layer absorber , graded band gap , deep trap center , trap density , SILVACO