Comparative study of electroluminescence from Cu(In,Ga)Se2 and Si solar cells

Abstract The electroluminescence (EL) of high-efficiency mono-crystalline silicon solar cells is compared to that of polycrystalline ZnO/CdS/Cu(In,Ga)Se 2 heterojunction solar cells. Both types of devices exhibit a remarkable efficiency as light emitting diodes. The external quantum efficiency Q LED defined as the ratio between radiative and total recombination currents is Q LED ≈ 0.13% in case of the silicon cell and Q LED ≈ 0.03% for the Cu(In,Ga)Se 2 device. The luminescent emission of Cu(In,Ga)Se 2 changes from a broadened donor–acceptor pair recombination at temperatures T T > 200 K. The emission of the silicon cell is dominated by transverse optical phonon assisted band-to-band recombination in the entire temperature range 90 K ≤ T ≤ 300 K. The reciprocity between the external (photovoltaic) quantum efficiency Q e and the electroluminescent emission of both devices is fulfilled.