Cu(In,Ga)Se-2 solar cells, numerical simulation and analysis

In this work, we have used a one-dimensional simulation program called the solar cell capacitance simulator (SCAPS) to design solar cells with the structure SnOx/CdS/CIGS (SnOx window, CdS buffer and CIGS absorber material) and study their performance. To improve efficiency we have used a grading layer of CIGS but with different band-gaps. Cu(In,Ga)Se-2 has grading band-gaps varying in range from 1.04 to 1.68 eV, with the corresponding Ga content x = 0 to 1. The grading layer used improves the open-circuit voltage (V-OC) and also the short-circuit current density (J(SC)). Photovoltaic parameters were determined using the current density-voltage (J-V) curve. In addition, we have studied the effects of operating temperature on grading layer CIGS solar cells. Our numerical simulation gives some important indications to lead to higher efficiency of CIGS solar cells.