Structure, morphology and optical parameters of spray deposited CZTS thin films for solar cell applications

Ramesh B Mahewar

doi:10.17485/ijst/v13i21.642

Abstract

Objectives: To develop simple method for Cu2ZnSnS4 (CZTS) thin film deposition suitable for solar cell device application. Method: Cu2ZnSnS4 (CZTS) thin film was deposited by using simple chemical spray pyrolysis technique for substrate temperature (270±5) ◦C. Analytical reagent Grade 0.025 M Copper chloride (CuCl2), 0.0125 M zinc chloride (ZnCl2), 0.0125 M Tin chloride (SnCl4.5H2O) and 0.05 M Thiourea (SC (NH2)2) were used as sources of copper (cu+ ), zinc (Zn+), tin (Sn+ ) and sulfur (S- ) ions respectively. The structure, morphology and optical band gap of the film were investigated by using X-ray Diffractometer (XRD), Scanning Electron Micrograph (SEM) and UV-Visible spectroscopy respectively. Energy dispersive X-ray Analysis (EDX) was used for elemental analysis of deposited CZTS film. Findings: The XRD spectra showed that CZTS film exhibit polycrystalline tetragonal crystal structure with preferential orientation along (112) plane. The crystallite size calculated using full width at half maximum (FWHM) of (112) peak was to be 36.82 nm. SEM image revealed that film composed of regular arrangement of spherical granules of average size 1.61 µm. The purity of the CZTS phase was confirmed by elemental analysis. The calculated energy band gap (Eg) by using Tauc\'s plot was about 1.62 eV. The dc resistvity estimated by using IV characteristics of the CZTS film was to be 2.3× 10-2 Ω-cm. It is concluded that CZTS film prepared using present deposition technique can be used for solar cell device applications. Keywords: Chemical spray technique; CZTS Thin Films; band gap; structure of CZTS; electrical resistivity; elemental analysis

Highlights

In past four decades scientists all over the world are continuously taking efforts to develop high efficiency, solar cell devices
CZTS thin film was deposited on simple soda lime glass substrates by chemical spray pyrolysis technique using locally available perfume atomizer
The X-ray Diffractometer (XRD) results showed that prepared films were polycrystalline, tetragonal crystal structure

Summary

Introduction

In past four decades scientists all over the world are continuously taking efforts to develop high efficiency, solar cell devices. In recent years researchers are much more interested to develop thin film solar cells based on chalcoegnide compound of stoichiometry Cu2(MII (MIV) S, Se) (MII=Mn, Fe, Ni, Zn, Cd, Hg) and MIV =(In, Ge, Sn.). Extensive work have been reported on Cu2 (InGa) Se2 based thin film solar cells of conversion efficiency up to 20.6 %. Cu2ZnSnS4 (CZTS) compound is quaternary p-type semiconductor has direct optical band gap about 1.2-1.5 eV and absorption coefficient 104 cm-1very similar to CIGS type thin film solar cells[2,3]. The elements used in fabrication of CZTS material were non-toxic, higher abundance and very economic and Cu2ZnSnS4 (CZTS) is one of the most promising quaternary materials exhibited 9.6 % conversion efficiency[4]

Objectives

Methods

Results

Conclusion