Efficiency enhancement of AlGaInP based light emitting diodes via polystyrene microlens array

A low cost and simple route was presented to fabricate large-scale ordered microlens arrays on gallium phosphide light emitting diodes with enhanced extraction efficiency. The different morphological microlens arrays were simply fabricated by controlling heat treatment temperature. Light extraction efficiency and light output power of gallium phosphide light emitting diodes were enhanced by different array structures of the polystyrene microlens. Compared to conventional gallium phosphide light emitting diodes, light intensity of the light emitting diodes covered by hemispherical polystyrene microlens shows 1.32 times enhancement under the forward current of 20 mA. The mechanism of enhanced light output with microlens arrays is discussed in detail.