Title :
Modeling the Effects of Na Incorporation on CIGS Solar Cells
Author :
Mungan, Elif Selin ; Xufeng Wang ; Alam, Md. Ashraful
Author_Institution :
Sch. of Electr. & Comput. Eng., Purdue Univ., West Lafayette, IN, USA
Abstract :
In this paper, we quantitatively evaluate the relative importance of three mechanisms that are proffered by various groups to interpret the effects of sodium (Na) incorporation in copper indium gallium diselenide solar cells. The suggested mechanisms are 1) increase in the carrier density due to defect passivation; 2) spatial redistribution of gallium (Ga); and 3) change in the crystal orientation. The simulation framework which is developed for this purpose indicates that, among these three coexisting effects, the increase in the carrier density with Na incorporation is likely to be most important. If the grain boundaries (GBs) initially contain donor-like traps that are subsequently passivated by Na, the increase in carrier density can improve the cell efficiency significantly. On the other hand, we find that the effects of Ga redistribution and change in crystal orientation are limited.
Keywords :
carrier density; copper compounds; crystal orientation; gallium compounds; grain boundaries; indium compounds; solar cells; ternary semiconductors; CIGS solar cells; Cu(InGa)Se2; Na incorporation; carrier density; copper indium gallium diselenide; crystal orientation; defect passivation; donor-like traps; grain boundaries; spatial redistribution; Charge carrier density; Doping; Electron traps; Materials; Photonic band gap; Photovoltaic cells; Spontaneous emission; Grain boundaries (GBs); photovoltaic (PV) cells; semiconductor device modeling; thin-film devices;
Journal_Title :
Photovoltaics, IEEE Journal of
DOI :
10.1109/JPHOTOV.2012.2221082