An Estimate of Maximal Conversion Efficiency in Regard to Doping Concentrations and Junction Position in Cu(In,Ga)Se2 Solar Cells

The built-in potential, carrier collection and eventually the conversion efficiency of the Cu(In,Ga)Se₂-based solar cell were calculated for the best performance as a function of doping concentrations coupled with the arrangement of the junction location. The results were illustrated as contour maps on donor-acceptor concentration coordinates. It was shown that the conversion efficiency map becomes a saddle shape because a reduced space charge region of high doping concentration limits carrier collection due to small minority carrier diffusion length in CIGS, indicating that a high doping concentration does not necessarily results in high performance. Besides it can be said that buried junction formation fortunately makes device design condition less heavy