Influence of Thiourea Concentration on Some Physical Properties of Chemically Sprayed Cu<sub>2</sub>ZnSnS<sub>4</sub> Thin Films

Abstract

In this work Cu 2 ZnSnS 4 (CZTS) films were deposited by using chemical spray pyrolysis (CSP) technique at substrate temperature of (400 ± 10) °C and thickness of about (300 ± 10) nm at different Thiourea Concentrations of (0.14, 0.16, 0.18, 0.20, 0.22 and 0.24) M. Copper chloride (CuCl), zinc chloride (ZnCl 2), tin chloride (SnCl 4 .5H 2 O) and thiourea (SC(NH 2) 2) were used as sources of copper ions, zinc ions, tin ions and sulfur ions respectively. The structural, morphological and optical properties of these films have been studied using XRD, AFM, and UV-Visible spectroscopy respectively. The XRD results showed that all films are polycrystalline in nature with tetragonal structure and preferred orientation along (112) plane. The crystallite size (D av) of all samples was calculated using Scherrer's equation and it is found that the sample deposited at thiourea concentration of 0.20 M has maximum crystallite size of 31.25 nm, while it was minimum (18.02 nm) for the sample prepared at thiourea concentration of 0.16 M. The AFM results showed smooth and homogenous thin films. The optical energy band gap (E g) for allowed direct electronic transition was calculated using Tauc's plot. It is found that the energy band gap (E g) decreases as the thiourea concentration increases and it was in the range of (2.22-1.75) eV. Urbach energy, refractive index, extinction coefficient and dielectric coefficient of all deposited films were estimated and the results were discussed.

Synthesis and Characterization of Copper-Zinc-Tin-Sulfide (CZTS) Thin Film Absorber Layer for Solar Cell Application

“…The CZTS thin film shows the (112), (220) and (312) planes corresponding to 2θ values of about 28.437°, 47.302° and 56.094° respectively. This result is almost congruent with the previous studies [17][18][19][20][21]. This ensures that the polycrystalline tetragonal structure, that is CZTS, is formed.…”

Heteroleptic Tin-Antimony Sulfoiodide for Stable and Lead-free Solar Cells

“…In addition, a large Urbach energy (463.7 meV) was observed for Sn 2 SbS 2 I 3 (Figure S9), which is close to that of Cu 2 ZnSnS 4 prepared using a similar precursor solution. 31 This large Urbach energy can be attributed to the high degree of disorder in the structure of Sn 2 SbS 2 I 3 . 32 However, XPS data shown in Figure 1D confirmed the presence of Sn, Sb, S, and I from the Sn 2 SbS 2 I 3 thin film.…”

Low-Cost CuIn1−xGaxSe2 Ultra-Thin Hole-Transporting Material Layer for Perovskite/CIGSe Heterojunction Solar Cells

“…Hereafter, Figure 6 shows a Tauc plot for measuring the energy band gap (E g ) at 1.25 eV for the CuIn 1−x Ga x Se 2 HTM grown on a bi-layer Mo/FTO glass-substrate. The band-gap was obtained by extrapolating the linear portion of (αhν) 2 vs. hν graph, where α, h and ν represent the absorption, Planck constant and radiation frequency [65,66]. The energy band gap is required to elevate a valence electron bound to an atom to become a conduction electron and a hole, which can be free to move as charge carriers to conduct an electrical current.…”