Optimization of Si (core)/CZTS/CZTSe (shell) nanowire array for solar cell

Mohamed Ahmed Cherif,Adnen Melliti

doi:10.1007/s11082-021-03022-7

Abstract

We present an optical simulation of a solar cell employing core (Si) /shell (Kesterite Cu2ZnSnS4 (CZTS) or/and Cu2ZnSnSe4 CZTSe) vertically-aligned nanowire array. The method of the simulation is rigorous coupled wave analysis. In the first stage, we studied the case where the shell is composed of only CZTS or CZTSe. A larger absorptance of CZTSe led to a larger value of the ideal short circuit current (41 mA/cm2) in the case of CZTSe solar cell than in the case of CZTS solar cell (24 mA/cm2). In the second stage, to avoid the heat losses in CZTSe solar cell without reducing the current, we proposed a shell composed of a 3 µm of CZTS in the upper part and a 6 µm of CZTSe in the lower part. The maximum ideal current value in this structure is almost twice as large as that of a planar solar cell with the same amounts of used materials. Furthermore, the variation of this maximal ideal current with the incident angle of the sunlight shows that the investigated solar cell still has good performance as long as the incident angle doesn’t exceed 60°.

Highlights

Thanks to its particular optical properties, like the light scattering and trapping [1,2,3], nanowires (NWs) configuration is economical than other configurations because solar cell (SC) have relatively less material
We present an optical simulation of a solar cell employing core (Si) /shell (CZTS or/and CZTSe) vertically-aligned nanowire array
To avoid the heat losses in CZTSe solar cell without reducing the current, we proposed a shell composed of a 3μm of CZTS in the upper part and a 6μm of CZTSe in the lower part

Summary

Introduction

Thanks to its particular optical properties, like the light scattering and trapping [1,2,3], nanowires (NWs) configuration is economical than other configurations because solar cell (SC) have relatively less material. 2. Device setup The structure of the solar cell, with square periodic array of NWs, investigated in this article are shown in figure 1.a. The NWs have n-Si core used as a buffer layer and coated by a thin CZTS or/and CZTSe absorber layer. A schematic of a planar solar cell (P SC), used to assess the improvement of the investigated solar cells caused by the using of the NWs configuration, is shown in figure 1.b. we note that The optical constants of Si, CZTS, CZTSe, and FTO, used in the simulation were taken from references [9,10,11,12], and the polarization of the incident light, perpendicular to the substrate surface, is along the axe (Ox).

Results and discussion

Optimization of the geometrical parameters

CZTSe NWs-solar cell