Characterization of quantum dot enhanced solar cells for concentrator photovoltaics

The addition of quantum dots (QDs) or quantum wells (QW) to a solar cell allows one to extend the absorption spectrum of the solar cell to match spectral conditions under concentration. In this paper the effect of bandgap tuning using quantum dots is investigated. P-i-n GaAs concentrator solar cells, both with and without InAs QD superlattice (SL) inserted into the i-region, were fabricated. In order to investigate effects of increased InAs QD layers, between 5 and 20 stacked InAs QDs were grown. The 20 layer stack QD tuned cell showed an 11% improvement in JSC compared to the baseline from concentrations of 2-450 suns. The increased Jsc of the QD devices was shown to be a direct result of photo-generated current contributed by the QDs. The 20X QD cell gave a 1% absolute efficiency enhancement, compared to a baseline solar cell, at 400 sun intensity, showing potential for QD spectral tuning under solar concentration.