Photovoltaic efficiency enhancement through thermal up-conversion

Anti-Stokes emission is observed experimentally from a series of quantum well p-i-n structures and is attributed to a quasithermal equilibrium being established between the quantum well and barrier material. A device is described whereby the anti-Stokes emission from a quantum well p-i-n structure can be used to increase the short-circuit current of a second conventional solar cell, essentially coupling sub-band-gap sunlight to the ambient thermal reservoir. For a GaAs p/n cell at 300 K, this effect is calculated to raise the one-sun power conversion efficiency from 30.0% to 31.3%. Greater efficiency increases are possible if a thermal gradient is established across the structure. (C) 2003 American Institute of Physics.