NOVELTY - The system comprises first and second electrodes, first and second photoactive layers provided between the first and second electrodes, and a recombination material (150) provided between the first and second photoactive layers. The first photoactive layer is present between the first electrode and the recombination material. The second photoactive layer is present the second electrode and the recombination material. The recombination material comprises a first hole blocking layer and a first hole carrier layer comprising an n-type semiconductor material and a polyamine.    USE - The system is useful as a tandem photovoltaic system (claimed).    ADVANTAGE - The system can be economically manufactured with reduced energy consumption in an environmental friendly manner.    DETAILED DESCRIPTION - The system comprises first and second electrodes, first and second photoactive layers provided between the first and second electrodes, and a recombination material (150) provided between the first and second photoactive layers. The first photoactive layer is present between the first electrode and the recombination material. The second photoactive layer is present the second electrode and the recombination material. The recombination material comprises a first hole blocking layer and a first hole carrier layer comprising an n-type semiconductor material and a polyamine. Molecules of the polyamine are cross-linked by a cross-linking agent. The first hole blocking layer has a thickness of 30-60 nm and a work function of 4.8-6.5 eV, and comprises a p-type semiconductor material. The system further comprises: a second hole blocking layer provided between the first electrode and the first photoactive layer, where the first photoactive layer is present between the second hole blocking layer and the first hole carrier layer; and a second hole carrier layer laid between the second electrode and the second photoactive layer, where the second photoactive layer is present between the first and second hole carrier layers. The second hole blocking layer is made from a material different from that used to make the first hole blocking layer. The p-type semiconductor material comprises a polymer and a metal oxide dispersed in the polymer.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic cross-sectional view of a tandem photovoltaic cell.    Substrate (110)    Electrode (120)    Optional hole blocking layer (130)    Photoactive layer (140)    Recombination material. (150)