Improving the figures of merit of intermediate band solar cells by controlling the capping procedure of the quantum dots

Abstract

Quantum dot intermediate band solar cells show great potential to outperform conventional tandem solar cells, but their performance is still far from the theoretically predicted expectations, mostly because of defects on the quantum dots' layers. The influence of the thickness of the quantum dots' cap layer and the temperature to which the sample is subjected after its deposition — the In flush temperature — on the figures of merit of InAs/GaAs based quantum dot intermediate band solar cells has been investigated. Cap layers of 3 nm produce solar cells with improved figures of merit, since the thinner layer limits the size of the QDs. Moreover, an increase by 5 %, 41 %, 22 % and 82 % in the short circuit current, open circuit voltage, fill factor and efficiency, respectively, is obtained when the In flush temperature changes from 630 oC to 700 oC. The outstanding improvement achieved in the figures of merit presented here shows their potential for the near future.