Lowering Cost Approach for CIGS-Based Solar Cell Through Optimizing Band Gap Profile and Doping of Stacked Active Layers─SCAPS Modeling
Francis Tchomb Mabvuer, Fridolin Tchangnwa Nya, Guy Maurel Dzifack Kenfack, A. Laref
Abstract
High Resolution Image Download MS PowerPoint Slide In this research article, we carry out investigation on compensating the efficiency loss in thin-film CIGS photovoltaic (PV) cell due to absorber coat depth reduction. We demonstrate that the efficiency loss is mainly caused by the disruption of the charge-carrier transport. We propose an architecture engineered with a stepped band gap profile for improving the efficiency of charge-carrier transport and collection. By modifying the gallium content, we tuned the band gap profile of the active layer of a reference experimental cell from which we previously collected all parameters. Using the simulator environment SCAPS-1D, we modeled a three-steps stacking profile of active layer with different gallium contents from one layer to another. Based on the results obtained, the band gap configuration herein proposed appears to be a prospective strategy for high-performance ultrathin Cu(In,Ga)Se 2 -based PV cell architecture engineering. By combining this approach with the optimization of the active layer doping, we enhanced the yields of the reference structure from 18.93% for a 2 μm active layer to 23.36% for only 0.5 μm thickness of active layer, that is, an enhancement of 4.4%. The fill factor increased from 73.24 to 81.73%, that is, an additional stability indicator value of 8.5%. The good values of the obtained efficiency and the improvement of the fill factor value are relevant indicators of a stable device. Active layer stacking combined with a stepped band gap profile and doping level optimization is definitely providing new perspectives in thin-film CIGS high-performance PV cell achievement.