Simulation of the Effects of the Thickness and the Bandgap of the Absorber on the Performance of the Quaternary Thin Film Solar Cell Based on Cu(In,Ga)Se<sub>2</sub>

Abstract

In the field of energy transformation, the share of renewable energies continues to grow and gives hope to fight against global warming. In the global electricity mix we have: 15% for hydropower, and 14.5% for other renewables, according to 2022 figures. Among renewable energies, photovoltaic (PV) solar energy is the most promising with very high record yields of around 29% theoretically, 27.3% experimentally for record-breaking PV solar cells in the laboratory and 22% in industrial production for a solar panel. The selenide, gallium, indium and copper (CIGS) sector is very promising, one of its major advantages coming that the fact the quaternary alloy Cu(In,Ga)Se<sub>2</sub> is a material with an adjustable bandgap (Eg). The freely available and highly stable one-dimensional solar cell capacities simulation software, is the tool used for the simulation. Digital simulation is an essential tool because it makes it possible to predict the behavior of the solar device and to be able to estimate its performances. The study of effects of the thickness (W<sub>CIGS</sub>) and the gap of the CIGS absorber with a cadmium sulfide buffer layer of 30 nm shows that current-voltage density characteristic is enormously affected for W<sub>CIGS</sub> ≤1000 nm. We therefore note a significant decrease in the values of the short-circuit current density (J<sub>SC</sub>) and the open-circuit voltage (V<sub>OC</sub>) when W<sub>CIGS</sub> decreases. These results are explained by a significant reduction in the quantity of incident photons absorbed and an increase in the recombination rate of the charge carriers photogenerated in the absorber. V<sub>OC</sub> increases and J<sub>SC</sub> decreases with the increasing of the absorber gap, the increase in V<sub>OC</sub> is therefore linked to a significant reduction in the recombination rate at the CIGS/Mo interface and inside the space charge region. The maximum efficiency is 26.33% for Eg = 1.45 eV and W<sub>CIGS</sub> = 3000 nm.