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)Se2-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.

No abstract

No abstract

No abstract

No abstract

In this chapter, we investigate a way of improving solar cells performances. By focusing studies on optimizing the structural, the opto-electrical and electronic properties of materials that constitute the layers and interfaces of a solar device, such as electrical susceptibility, doping concentration, mobility of charge carriers and crystallographic structure, it is possible to improve the output parameters of a solar cell. Working on a CIGSe-based second-generation ultra-thin solar cell model, and using Zinc Sulfide (ZnS) as a window layer, and based on recent studies, vital information are found on the optimal values of these properties that may enhance the efficiency of the cell. A correct modeling of the device with a trusted software such as SCAPS and an appropriate set of the exact conditions and parameters of simulation allow to obtain very promising results. In particular, for nanoscale and microscale thicknesses of buffer and absorber layers materials respectively, and with an appropriate choice of other materials properties such as intrinsic doping concentration, electrons and holes mobilities, it is possible to record efficiencies and fill factors of more than 26% and 85% respectively. These values are very promising for solar energy harvesting technologies development through CIGSe – ZnS based solar devices.