Crystallochemical Characterizations, Raman Spectroscopy and Studies Nuclear Magnetic Resonance (NMR) of Cu&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;Zn(Sn, Si)S&amp;lt;sub&amp;gt;4 &amp;lt;/sub&amp;gt; Compounds for Photovoltaic Applications

Mohamed Hamdi,Messaoud Benamira

doi:10.4236/msce.2022.101002

Abstract

In this study, Si-doped Cu2ZnSnS4 compounds (Cu2ZnSn1-xSixS4, 0 ≤ x ≤ 1) were prepared by solid state reaction method for use of materials for photovoltaic cells. The structural and spectroscopic properties of the as-prepared compounds were studied by X-ray diffraction (XRD), 119Sn, 29Si and 65Cu Magic Angle Spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. The Si-substitution in the Sn-site induces three different types of XRD patterns which depend largely on the Si content in the compound. For 0 ≤ x ≤ 0.5, XRD analysis reveals the presence of a pure tetragonal phase of solid solution with I-42m as a space group. Mixed tetragonal and orthorhombic phases were observed for 0.5 1 at high content of Si (x ≥ 0.8). 119Sn MAS NMR spectra show the presence of Sn/Si disorder as a function of the Si content. The 65Cu MAS NMR spectra of the quadratic solid solution confirm the presence of the two copper sites (Cu-2a and Cu-2c) at 780 ppm while in the case of the orthorhombic solid solution samples, a very broad band is observed. The optical properties were investigated of all compounds by UV-Vis diffuse reflectance and the obtained optical band gap values (1.31 to 2.43 eV) confirm a semiconductor character.

Highlights

Nowadays, the use of clean energy resources such as solar energy becomes one of the relevant challenges of researchers in order to limit the damage caused by the use of fossil energy
Mixed tetragonal and orthorhombic phases were observed for 0.5 < x < 0.8, followed by a pure orthorhombic structure with a space group Pmn21 at high content of Si (x ≥ 0.8). 119Sn Magic Angle Spinning nuclear magnetic resonance (MAS Nuclear Magnetic Resonance (NMR)) spectra show the presence of Sn/Si disorder as a function of the Si content
For 0 ≤ x ≤ 0.5, X-ray diffraction (XRD) analysis reveals the presence of pure phase of solid solution in which the peak positions shift for more positive values of θ while Si content increases in the kesterite structure

Summary

Introduction

The use of clean energy resources such as solar energy becomes one of the relevant challenges of researchers in order to limit the damage caused by the use of fossil energy. One of the most promising ways is the use of thin layers of semiconductor materials based on the compound Cu2ZnSnS4 (CZTS) as a light absorber instead of Cu(In, Ga)(S, Se) alloys which contain chemical elements with a limited availability [1]-[7]. CZTS semiconductor compound greater than 30% [8] and an energy band gap (Eg) value which varies between 1.4 and 1.7 eV depend on the method used to determine Eg value from the UV-Vis diffuse reflectance spectra and the preparation condition of this material [9] [10] [11]. The substitution of Sn by Si leads to a decrease in lattice volume due to the difference in atomic radii between Sn and Si. the two limit compounds of this series have two different crystal structures, Cu2ZnSnS4 with tetragonal phase and Cu2ZnSiS4 with orthorhombic phase

Experimental Section

Structural Analysis

Optical Properties

Conclusion