A photovoltaic converter, comprising an emitter structure made of silicon components able to convert high energy photons into free electrons in particular UV and visible photons as well as IR photons, this emitter structure being part of a slab, wafer or chip of p-type or n-type photovoltaic material, - said slab, wafer or chip having a top surface intended to be exposed to photonic radiation mainly to sun radiation, having a built-in PN junction delimiting the emitter part and a base part, having front and rear electrodes and comprising at least one area or region specifically designed or adapted to absorb high energy or energetic photons and located adjacent or near one hetero-interface between amorphized and crystalline (a-Si and c-Si) silicon, - said emitter of the photovoltaic material comprising also at least one metamaterial MTM region forming a low-energy secondary carrier generation cavity, which is contiguous or proximate to the at least one absorption area or region for the energetic photons and subjected to a built-in or applied electrical field having an intensity sufficient to withdraw and move away the secondary electrons liberated by the primary hot electrons from their initial sites within the concerned metamaterial MTM region, at a speed sufficient to prevent their return into said metamaterial MTM region, thus forming a substructure performing multistage conversion, wherein the density of divacancies within the metamaterial MTM region(s) is greater than 10 18 divacancies/cm 3, preferably greater than 10 19 divacancies/cm 3, most preferably greater than 10 20 divacancies/cm 3 and the conduction between the metamaterial MTM and the respectively adjacent n-type material has a time constant which is at the most of the same magnitude that the secondary carrier generation time constant, characterized in that, said emitter structure comprises - three amorphous silicon material layers buried at different depths and conformed by a process of insertion, deposition or implantation of ions or electrons into a relief made of a succession of protrusions separated by hollows or discontinuities in the shape of one or several continuous or discontinuous layer(s) - wherein the protrusions are strips, these strips are made of the amorphous silicon a-Si with a modified upper and lower surface consisting in the metamaterial MTM, wherein the strips are each resulting from at least one passage of a beam for ion implantation or electron irradiation. - said slab, wafer or chip having a top surface intended to be exposed to photonic radiation mainly to sun radiation, having a built-in PN junction delimiting the emitter part and a base part, having front and rear electrodes and comprising at least one area or region specifically designed or adapted to absorb high energy or energetic photons and located adjacent or near one hetero-interface between amorphized and crystalline (a-Si and c-Si) silicon, - said emitter of the photovoltaic material comprising also at least one metamaterial MTM region forming a low-energy secondary carrier generation cavity, which is contiguous or proximate to the at least one absorption area or region for the energetic photons and subjected to a built-in or applied electrical field having an intensity sufficient to withdraw and move away the secondary electrons liberated by the primary hot electrons from their initial sites within the concerned metamaterial MTM region, at a speed sufficient to prevent their return into said metamaterial MTM region, thus forming a substructure performing multistage conversion, wherein the density of divacancies within the metamaterial MTM region(s) is greater than 10 18 divacancies/cm 3, preferably greater than 10 19 divacancies/cm 3, most preferably greater than 10 20 divacancies/cm 3 and the conduction between the metamaterial MTM and the respectively adjacent n-type material has a time constant which is at the most of the same magnitude that the secondary carrier generation time constant, - three amorphous silicon material layers buried at different depths and conformed by a process of insertion, deposition or implantation of ions or electrons into a relief made of a succession of protrusions separated by hollows or discontinuities in the shape of one or several continuous or discontinuous layer(s) - wherein the protrusions are strips, these strips are made of the amorphous silicon a-Si with a modified upper and lower surface consisting in the metamaterial MTM, wherein the strips are each resulting from at least one passage of a beam for ion implantation or electron irradiation.