InGaAs quantum dot solar cells with high energygap matrix layers

We have fabricated InGaAs/AlGaAs quantum dots solar cells with a high band offset energy between quantum dot and barrier layers in order to suppress thermal escape of electrons out of the quantum dot layers. The external quantum efficiency of quantum dots solar cell increases between 550 and 900 nm wavelength due to additive contributions from quantum dot layers inserted in the p-n structure. Further, we have clearly observed a photocurrent production by two-step photon absorption at room temperature due to suppression of thermal escape of electrons out of the QD layers. The additive photocurrent by two-step absorption was 0.242 mA/cm², which is around 12.6 % of the total current density measured at AM 1.5 spectrum.