Light micrograph of a polycrystalline silicon solar cell. It produces electricity from sunlight (photovoltaic effect), a clean, renewable and ecological energy. A front electrode (-) or finger (made of silver nanoparticles) in a grid of metallic contacts (upper and lower white area). There is a very visible break in the silver finger, due to a defect in the screen printing process. The upper surface of the photovoltaic cell is an n-type layer, made of silicon semiconductor material. The blue coating layer of the microcrystals is made of silicon nitride for an anti-reflective effect. In this type of polycrystalline cell, the recombination produced in the boundaries of the faulty crystals reduces the photovoltaic efficiency. Field of view size: 290 x 440 痠 (0.012 x 0.017 in)