Title: Effect of alloying with Ruthenium on the properties of FeX2 (X=S, Se) thin films

Abstract

This research is interested in the fabrication of low-cost materials for several applications such as low-cost solar cells and several chemical applications. We focused on the Pyrite (FeS2, FeSe2,…etc) films because they are promising candidates for absorption and photocatalysis. Indeed, they are of great interest in applications of renewable energy conversion due to their high optical absorption coefficient (α>105 cm-1 for hν>1.4eV), their high abundance, their low cost, and their non-toxic constituent elements. Furthermore, the used technique for the fabrication of our pyrite layers is easier than others used previously, and it’s environmentally safe: it consists of spraying an aqueous solution of FeCl3.6H2O on pre-heated glass substrates followed by their heat treatment under sulfur or selenium atmosphere. However, after fabrication, the band gap energy values of the obtained pyrite films are close to 1eV that are shown relatively low for solar cells application. Thus, to develop pyrite-based photovoltaic, searching for practical ways to enlarge the band gap of FeS2 and FeSe2 is greatly necessary in the aim to achieve the optimum band gap energy value, for single-junction photovoltaic applications, within Shockley- Queasier theory, of about 1.5 eV. Alloying with ruthenium was our successful used technique. The fabricated Ru-alloyed pyrite films presented desired band gap energy values for several applications, especially for photovoltaic ones.