Investigation of Base High Doping Impact on the npn Solar Cell Microstructure Performance Using Physically Based Analytical Model

Marwa S S Basyoni,Ahmed Shaker,A Zekry

doi:10.1109/access.2021.3053625

Marwa S S Basyoni, Ahmed Shaker + Show 1 more

Open Access

https://doi.org/10.1109/access.2021.3053625

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Abstract

Recently, there is a rapid trend to incorporate low cost solar cells in photovoltaic technology. In this regard, low-cost high-doped Silicon wafers are beneficial; however, the high doping effects encountered in these wafers render their practical use in fabrication. The npn solar cell microstructure has been found to avoid this issue by the proper design of vertical generation and lateral collection of the light generated carriers. We report on the impact of the p + base doping concentration, up to 2 × 10 19 cm -3 , on the npn microstructure performance to find the most appropriate way for high efficiency. To optimize the structure, a series of design steps has been applied using our previously published analytical model. Before inspecting the high doped base effect, firstly, the n + emitter is optimized. Secondly, the impact of bulk recombination inside the p + base is introduced showing the range of optimum base width (W p ). Then, we investigate thoroughly the impact of base doping levels for different base widths to get the optimum W p that satisfies maximum efficiency. The results show that for p + base doping concentration ranging from 5 × 10 17 cm -3 to 2 × 10 19 cm -3 , the npn microstructure efficiency decreases from 15.9% to 9%, respectively. Although the efficiency is degraded considerably for higher doping levels, the structure still achieves a competitive efficiency at higher doping levels, for which its cost is greatly reduced, in comparison with thin film solar cells. Moreover, using higher doping permits lesser wafer area which could be beneficial for large area solar cells design.design.

Highlights

Solar cell technology is one of the fastest developing fields nowadays
In the last few years, the single crystalline silicon solar cells were competed by the thin-film solar cells (TFSCs) due to the low cost of TFSCs and the rapid improvement in its efficiency [1]
In [16], we developed a physically based analytical model which has shown a good accuracy and fast computational time compared to TCAD simulation

Summary

Introduction

Solar cell technology is one of the fastest developing fields nowadays. In the last few years, the single crystalline silicon solar cells were competed by the thin-film solar cells (TFSCs) due to the low cost of TFSCs and the rapid improvement in its efficiency [1]. TFSCs have some restrictions, such as their limited effectiveness in absorbing the long wavelengths of solar radiation spectrum due to the small thickness of its active layer [2]. Most of TFSCs encounter toxic materials in their structures [3]. Those are some of the reasons behind that TFSCs need more researches and investigations to be commercially available.

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