NOVELTY - A solar cell (10) includes optical downshifting layer (30) that is transmissive to incident photons having wavelengths in primary light absorption spectrum and having optically complementary nanomaterial for absorbing incident photons in supplemental light absorption spectrum, the optically complementary nanomaterial being used for emitting photons in primary light absorption spectrum such that an optical downshifting layer transforms incident photons in the supplemental light absorption spectrum into photons in the primary light absorption spectrum.    USE - A solar cell.    ADVANTAGE - The solar cell has photoabsorptive nanomaterial layer that downshifts certain wavelengths of incident light into wavelength region that is better absorbed by the photovoltaic material of the solar cell. Light conversion efficiency of the solar cell is increased by employing the downshifting nanomaterial to supplement the activity of photovoltaic material.    DETAILED DESCRIPTION - Solar cell (10) comprises:    (1) photovoltaic material (22) having region of light conversion activity with primary light absorption spectrum for absorbing incident photons and generating electron, and hole charge carriers in photovoltaic material;    (2) spaced-apart first and second electrodes for containing the photovoltaic material between them, the photovoltaic material and the electrodes forming respective first and second charge-separating junction interfaces for separating the electron and hole charge carriers for collection by the electrodes, one of the electrode having electrode material that transmits incident light wavelengths in the primary light absorption spectrum to permit incident photons in the primary light absorption spectrum to reach the photovoltaic material, the electrode material having a doping characteristic that enhances electrical performance characteristic of the solar cell, and the doping characteristic impeding light conversion activity of the photovoltaic material in supplemental light absorption spectrum that is outside of the primary light absorption spectrum to avoid reduction of light conversion activity of the photovoltaic material in the primary light absorption spectrum; and    (3) optical downshifting layer (30) that is transmissive to incident photons having wavelengths in the primary light absorption spectrum and having optically complementary nanomaterial for absorbing incident photons in the supplemental light absorption spectrum, the optically complementary nanomaterial being used for emitting photons in the primary light absorption spectrum such that the optical downshifting layer transforms incident photons in the supplemental light absorption spectrum into photons in the primary light absorption spectrum to enhance generation of electron and hole charge carriers in the photovoltaic material, the optically complementary nanomaterial increasing light conversion efficiency of the solar cell such that light conversion efficiency increased by the optically complementary nanomaterial is greater than any decrease in light conversion efficiency caused by the doping characteristic.    An INDEPENDENT CLAIM is included for supplementing light conversion efficiency of photovoltaic material of wafer-based solar cell platform.    DESCRIPTION OF DRAWING(S) - The drawing is an enlarged simplified cross-sectional view of a solar cell.    Solar cell (10)    Solar cell platform (20)    Photovoltaic material (22)    Emitter electrode (24)    Downshifting layer (30)