Improved interface between a I-III-VI2 layer and a rear contact layer, in a photovoltaic cell

The invention relates to a method of manufacturing a I-III-VI2 layer with photovoltaic properties, comprising: deposition of a metal on a substrate to form a contact layer, deposition of a precursor of the photovoltaic layer, on the contact layer, and heat treatment of the precursor with an addition of element VI to form the I III VI2 layer. The element VI usually diffuses into the contact layer (MO) during the heat treatment and combines with the metal to form a superficial layer (SUP) on the contact layer. In the method of the invention, the metal deposition comprises a step during which an additional element is added to the metal to form a compound (MO-EA), in the contact layer, acting as a barrier to the diffusion of the element VI, which allows precisely controlling the properties of the superficial layer, particularly its thickness.