NOVELTY - A solar concentrator comprises a substrate (100) and at least two closely spaced chromophores disposed on or in the substrate or optionally in a film disposed on the substrate, in a manner to receive optical (solar) radiation (120), the first chromophore effective to absorb wavelength of the optical radiation and further effective to transfer energy by Forster energy transfer to the second chromophore, the second chromophore effective to emit at least some of the transferred energy at a wavelength that is red-shifted from the wavelength absorbed by the first chromophore.    USE - In tandem device (claimed) to convert solar energy into electrical energy.    ADVANTAGE - The solar concentrators provide higher efficiencies, fewer components, improved materials and improved optical properties; and may be produced at a lower cost. The combination of luminescent solar concentrator (LSC) with a thin film solar cell provides cheaper method to improve the module efficiency compared to just the underlying solar cell alone.    DETAILED DESCRIPTION - A solar concentrator comprises a substrate (100) and at least two closely spaced chromophores disposed on or in the substrate or optionally in a film disposed on the substrate, in a manner to receive at least some optical (solar) radiation (120), the first chromophore effective to absorb at least one wavelength of at least some of the optical radiation and further effective to transfer at least some energy by Forster energy transfer to the second chromophore, the second chromophore effective to emit at least some of the transferred energy at a wavelength that is red-shifted from the wavelength absorbed by the first chromophore. The solar concentrator further comprises red-shifting agent, wavelength selective mirror, polar matrix and photovoltaic cells. An INDEPENDENT CLAIM is included for a tandem device comprising the solar concentrator coupled to a thin film photovoltaic cell, where the solar concentrator and the thin film photovoltaic cell are each selected to have different bandgaps.    DESCRIPTION OF DRAWING(S) - The figure shows the solar concentrator.    Substrate (100)    Edge (110)    Solar radiation (120)    Re-radiated energy (130)