Effect of Position-Dependent Doping on Intermediate Band Generation-Recombination Rate in InAs/GaAs Quantum Dot Solar Cell

InAs/GaAs quantum dot solar cells (QDSCs) with
n
-type delta-doped quantum dots (QDs) have gained immense interest due to their improved open-circuit voltage. Here we report the effect of position-dependent doping on the intermediate band generation-recombination rate through theoretical modelling to analyze the reduced short-circuit current density (
J_SC
) due to doping. A 1-D drift-diffusion model was used to obtain the photovoltaic characteristics. Simulations suggest that the intermediate band's contribution reduces by almost three orders of magnitude for the doped case near the
n
-doped base at short-circuit conditions compared to the undoped case. We utilized these findings to develop spatially varying doping conditions. The structure with doped QDs exhibit the highest power conversion efficiency (PCE) but minor
J_SC
enhancement. Comparatively, when the QDs near the
n
-doped base are kept undoped, better results are obtained at low bias, and a
J_SC
enhancement of 0.322 mA/cm
²
is observed. With the increase in bias above 0.68V, recombination becomes dominant in the proposed partially doped structure. These observations are backed by the occupation probability of the QDs, electron and hole carrier dynamics, and electric field distribution along the intrinsic region. With such an arrangement, PCE is enhanced by 0.69% compared to that of the undoped QDSC.