Efficiency enhancement of solar cells using multi-layer interdiffused InGaAs/ GaAs quantum dots: A numerical approach

Abstract

In this work, a mathematical model has been developed to analyze the effect of the number of quantum dot layers on the performance of solar cells. We have developed an analytical expression to obtain the spectral response and conversion efficiency of p-i-n solar cells with multi-layer interdiffused InGaAs quantum dots embedded in the GaAs matrix. Each layer consists of lens-shaped quantum dots having a non-homogenous composition due to interdiffusion. The comparative analysis of as-grown and interdiffused dots shows that neglecting the effect of interdiffusion leads to an overestimation of the photocurrent density of a solar cell. According to this study, including QDs layers increases the EQE toward longer wavelengths, increasing the short circuit density. However, a trade-off is observed between the photocurrent and open circuit voltage on increasing the number of quantum dot layers. In the proposed model, we have incorporated the impact of interdiffusion to predict the photocurrent density and open-circuit voltage of realistic-shaped quantum dot-based solar cells. In addition, the effect of spacer layer thickness on photocurrent density has also been discussed. The computed values were reasonably consistent with the reported experimental data.