Radiative efficiency limits of solar cells with lateral band-gap fluctuations

The radiative recombination limit of photovoltaic power conversion under one sun terrestrial illumination is calculated for solar cells with lateral fluctuations of the band-gap energy. A simple analytical model quantifies the fluctuations by the standard deviation sigma(Eg) from the mean band gap. The calculated maximum efficiency decreases by 1.7% (absolute) for sigma(Eg)=50 meV and by 6.1% for sigma(Eg)=100 meV with respect to a uniform band gap. (C) 2004 American Institute of Physics.