One dimension solar cells simulator package (SCAPS) is used to study the possibility of carrying out thin CIGS solar cells with high and stable efficiency. In the first step, we modified the conventional ZnO:B/i-ZnO/CdS/SDL/CIGS/Mo structure by substituting the SDL layer with the P + layer, having a wide bandgap from 1 to l.12 eV. Then, we simulated the J-V characteristics of this new structure and showed how the electrical parameters are affected. Conversion efficiency of 18.46% is founded by using 1.1 μm of P + layer thickness. Secondly, we analyze the effect of increase thickness and doping density of CIGS, CdS and P +  layers on the electric parameters of this new structure. We show that only the short-circuit current density (JSC) and efficiency are improved, reaching respectively 34.68 mA/cm² and 18.85%, with increasing of the acceptors density. Finally, we introduced 10 nm of various electron reflectors at the CIGS/Mo interface in the new structure to reduce the recombination of minority carriers at the back contact. High conversion efficiency of 23.34% and better stability are obtained when wide band-gap BSF is used.

In this study, glass frit was coated uniformly on the surface of Al particles instead of adding glass frit to Al powder by simple mixing to form a nano-layer. The influence of the glass-frit coating on the formation of the back-surface field and electrical characteristics of the resulting Al electrode were investigated. Microstructural observations indicated that the glass components were uniformly distributed and the back-surface field layer thickness was more uniform compared to the simply mixed sample. In addition, the sheet resistance was ˂10 mΩ/□, much lower than the 23 mΩ/□ of the simply mixed Al electrode.