Volume: 8 Issue 2 [February 2025]

Article:Effects of Carrier Supply to the Intermediate Band by Impurity Doping on Two-Step Photocurrent Generation in GaAs:N-Based Intermediate Band Solar Cell

Author: Md Faruk Hossain, Shuhei Yagi , Hiroyuki Yaguchi

Volume: Volume 8, Issue 2, February 2025

DOI: North American Academic Research, 8(2), 112-128. doi: https://doi.org/10.5281/zenodo.14910609

Abstract: This study investigates the enhancement of two-step photocurrent generation in GaAs:N-based intermediate band solar cells (IBSCs) by optimizing the doping concentrations within the absorber layer. Utilizing the combination of device simulations and rate equation analysis, we examine the influence of doping levels of absorber on the key photovoltaic parameters and expected current increase due to two-step photon absorption. The results reveal that increasing the doping concentration enhances the number of electrons occupying the intermediate band (IB). Those electrons contribute to the low-energy photon absorption and the following additional current generation. However, the doping simultaneously reduced open-circuit voltage and fill factor due to the weakened electrical isolation of the IB from the contact layer. The expected efficiency gain due to the two-step photocurrent generation is unfortunately, too small to compensate for the drop in the base efficiency in the investigated structures. However, these results suggest that carrier supply to the IB states by means of impurity doping can be an effective option for structural optimization of IBSCs. These findings underscore the importance of carefully tuning the doping levels to maximize the efficiency of IBSCs and provide critical insights for the design of next-generation solar cells

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