Characterisation of InAs/GaAs quantum dots intermediate band photovoltaic devices

The authors report on the structural, the optical and the electrical properties of solar cells containing 20 layers of doped InAs/GaAs quantum dots (QDs). The structures were grown by molecular beam epitaxy and contain n dopant sheet densities of 8 and 16 ?? 10¹⁰ cm^??2, respectively, in between the QD layers. Under a 1 sun illumination, the open-circuit voltage (V_oc) and the efficiency of the 8 ?? 10¹⁰ cm^??2 n-doped sample were increased to values of 0.73 V and 9.7%, respectively, compared with a reference undoped sample (a V_oc of 0.70 V and an efficiency of 9.0%). However, the short-circuit current density (J_sc) decreased from 20.1 to 17.4 mA/cm² indicating bandfilling within the QD array.