NOVELTY - A system comprises first and second electrodes (410, 490); a recombination layer (450) between the first and second electrodes; a first photoactive layer between the first electrode and the recombination layer; and a second photoactive layer between the second electrode and the recombination layer, where the recombination layer comprises third, fourth, and fifth layers. The fifth layer is between the third and fourth layers, and the system is configured as a photovoltaic system.    USE - As system e.g. a tandem photovoltaic cell (claimed) useful to transfer energy in the form of light into energy in the form of electricity.    ADVANTAGE - The polymer whose absorption wavelengths shift toward the red and near IR regions of the electromagnetic spectrum, is incorporated into a photovoltaic cell (e.g. tandem photovoltaic cell) together with a conventional semiconductive polymer (e.g. P3HT), it enables the cell to absorb the light in this region of the spectrum, and increases the current and efficiency of the cell. The light not absorbed by one photoactive layer is absorbed by another photoactive layer, and increases the efficiency of the photovoltaic cell. The anti-reflective or anti-reflection (AR) coating on the photovoltaic cell minimizes the amount of incident light that is reflected on the surface of the photovoltaic cell and increases the amount of the incident light available for absorption by the photovoltaic cell.    DETAILED DESCRIPTION - A system comprises either first and second electrodes (410, 490); a recombination layer (450) between the first and second electrodes; a first photoactive layer between the first electrode and the recombination layer; and a second photoactive layer between the second electrode and the recombination layer, where the recombination layer comprises third, fourth, and fifth layers, the fifth layer is between the third and fourth layers, and the system is configured as a photovoltaic system; or first and second electrodes; a first photoactive layer between the first and second electrodes; a second photoactive layer between the second electrode and the first photoactive layer; and third, fourth, and fifth layers between the first and second photoactive layers, where the fifth layer is between the third and fourth layers, and the system is configured as a photovoltaic system and the third, fourth, and fifth layers are configured such that, during use, electrons generated in one of the first and second photoactive layers and holes generated in the other of the first and second photoactive layers are recombined at the fifth layer.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a tandem photovoltaic cell.    photovoltaic cell (400)    cathode (410)    hole carrier layer (420)    photoactive layers (430, 470)    n-type semiconductor material layer (440)    recombination layer (450)    p-type semiconductor material layer (460)    hole blocking layer (480)    anode. (490)