Influence of band gap profiling in front part of absorber on CIGS solar cell performance

The computer simulation tool Analysis of Microelectronic and Photonic Structures (AMPS-ID) was employed. This work investigates the effects of a band-gap grading profile close to the linear in the region close to the junction Copper-Indium-gallium-deselenide (CIGS) based solar cell performance for a constant values of front band-gap (E_gfront) and d (width of the forward grading) equal to 1.28 eV and 0.25μm, respectively the sublinear profile presents the best performance where an increase of efficiency reaches (0.2%) is noted contrary to the supralinear profile which presents a decreasing of efficiency by about (0.8%) comparing to the linear profile value and this is due to the effects of traps varies with the band-gap. With varying d and E_gfront the difference between linear and supralinear profiles increases more than that between linear and sublinear ones, but the E_gfront is more decisive where we noted for a value equal 1.35 eV the drop of efficiency for supralinear profile reaches (2.2%) and an increases by (1.4%) for sublinear one. The width of the forward grading at the limit of the space charge region (SCR) yields a decrease by (0.8%) for supralinear profile and an increase by (0.7%) for sublinear one of the efficiency comparing to the linear profile value.