Signature of intermediate band materials from luminescence measurements

The intermediate band concept for photovoltaic power conversion promises a remarkable efficiency increase over conventional solar cells and relies on the existence of an electrically isolated intermediate band located between the conduction and valance bands. By identifying the luminescence signature of an intermediate band material, a characterization technique is described that can determine whether the required optically active intermediate band exists in electrical isolation in the material. The technique will help researchers identify promising intermediate band materials and further optimize their properties, without having to fabricate highly efficient photovoltaic devices.