Figure 1. Schematic of ZnO/CdS/CIGS solar cell structure (a),(b) ZnO/CdS/CIGS-Si solar cell CIGS structure
Where ψ the electrostatic potential, the free electron n and free hole p, trapped electron nt and trapped hole pt as well as ionized donor-like doping ND+ and ionized acceptor-like doping NA- concentrations are all given in terms of the different band gap energy levels by the Boltzmann and Fermi-Dirac distributions, and are a function of the position “x”. Jn and Jp are the electron and hole current densities respectively. The term Gop is the optical carrier generation rate due to illumination and R is the total recombination rate accounting for direct (band to band) and indirect (Shockley-Read-Hall) recombination traffics.