The invention relates to a method for filtering electrons, enabling spin polarization of an electron current to be obtained at an at least 75% Fermi level, implemented by a spin-polarised current source (2). The spin-polarised current source (2) comprises: a polarized-spin injector device comprising an electroconductive substrate (10) having a first surface (11) that has magnetic properties and an organic layer (20) in contact with the first surface of the substrate; an electroconductive material, called mass (30), the organic layer being arranged between the earth and the substrate; and a current source (40) that is electrically connected to the first surface of the substrate and to the earth. The invention involves generating the circulation of the electron-conducting current by means of the current source, between the first surface of the substrate and the earth, at a temperature higher than -220 DEG C.