A luminescent solar concentrator (LSC) is a device for concentrating radiation, solar radiation, in particular, to produce electricity. Luminescent solar concentrators operate on the principle of collecting radiation over a large area, converting it by luminescence (specifically by fluorescence), and directing the generated radiation into a relatively small output target.
Initial designs typically comprised parallel thin, flat layers of alternating luminescent and transparent materials, placed to gather incoming radiation on their (broader) faces and emit concentrated radiation around their (narrower) edges. Commonly the device would direct the concentrated radiation onto solar cells to generate electric power.
The layers in the stack may be separate parallel plates or alternating strata in a solid structure. In principle, if the effective input area is sufficiently large relative to the effective output area, the output would be of correspondingly higher irradiance than the input, as measured in watts per square metre. The concentration factor is the ratio between output and input irradiance of the whole device.
For example, imagine a square glass sheet (or stack) 200 mm on a side, 5 mm thick. Its input area (e.g. the surface of one single face of the sheet oriented toward the energy source) is 10 times greater than the output area (e.g. the surface of four open sides) – 40000 square mm (200×200) as compared to 4000 square mm (200x5x4). To a first approximation, the concentration factor of such an LSC is proportional to the area of the input surfaces divided by the area of the edges multiplied by the efficiency of diversion of incoming light towards the output area. Suppose that the glass sheet could divert incoming light from the face towards the edges with an efficiency of 50%. The hypothetical sheet of glass in our example would give an output irradiance of light 5 times greater than that of the incident light, producing a concentration factor of 5