Growth and Characterization of Cu2Zn1−xFexSnS4 Thin Films for Photovoltaic Applications

Abstract

Photovoltaics is a promising technology to produce sustainable energy, thanks to the high amount of energy emitted by the sun. One way of having solar cells with low production costs is to apply thin-film technology and with earth-abundant raw materials. A keen interest is arising in kesterite compounds, which are chalcogenides composed of abundant and non-toxic elements. They have already achieved excellent performance at the laboratory level. Here, we report the synthesis and characterization of mixed chalcogenides based on copper, zinc, iron, and tin. Solutions have been studied with different zinc and iron ratios. The distortion of the elementary cell of kesterite increases with the addition of iron until a phase transition to stannite occurs. The process of synthesis and deposition proposed herein is cheap and straightforward, based on the sol-gel technique. These thin films are particularly attractive for use in cheap and easily processable solar cells. The synthesized layers have been characterized by X-ray diffraction, UV-Vis absorption, and Raman, X-ray photoelectron, and energy-dispersive X-ray spectroscopy measurements.

Band-Gap Tuning Induced by Germanium Introduction in Solution-Processed Kesterite Thin Films

“…However, no pronounced enhancement of the band gap has been reported for this methodology, which does not exceed values around 1.5–1.6 eV. 12 − 15 On the other hand, studies of Cu substitution with Ag or Li have been attempted successfully with the remarkable growth of the band gap (until 1.8 eV) but with the disadvantage to complicate the whole production procedure by using precursors that are more expensive or in other cases more difficult to handle. 16 , 17 Last but not least, in the last few years, Sn substitution with Ge have drawn the attention of the PV research community due to the extremely high band gap reachable, especially with the completely Ge-substituted pure-sulfide kesterite version.…”

“…In this context, the need to produce high-band-gap materials to be used as top cells in tandem architectures , has addressed the research toward the substitution of Zn with Fe, Mn, or Co in pure-sulfide CZTS solar cells, given that selenium is known for lowering the energy gap. However, no pronounced enhancement of the band gap has been reported for this methodology, which does not exceed values around 1.5–1.6 eV. − On the other hand, studies of Cu substitution with Ag or Li have been attempted successfully with the remarkable growth of the band gap (until 1.8 eV) but with the disadvantage to complicate the whole production procedure by using precursors that are more expensive or in other cases more difficult to handle. , Last but not least, in the last few years, Sn substitution with Ge have drawn the attention of the PV research community due to the extremely high band gap reachable, especially with the completely Ge-substituted pure-sulfide kesterite version. Several works report different compositions of Cu 2 ZnSn x Ge 1– x (S,Se) 4 (CZTGSSe) and relate them to the optical and physical properties of the final absorber. − The results were interesting, especially in pure sulfide CZTGS where band-gap values ranging from 1.5 (for CZTS) to 2.1 eV (pure CZGS) have been registered. , Many different deposition techniques have been used, but no one allowed to reach remarkable results in terms of solar device performances for very high band gaps, exceeding 1.7 eV.…”

Exceptional Thermoelectric Performance of Cu2(Zn,Fe,Cd)SnS4 Thin Films

“…The peaks for Fe 2p 1/2 and Fe 2p 3/2 are located at 724.5 and 711.0 eV (Figure 2e), which is indicative of Fe(II), and similar to previous measurements on Cu 2 FeSnS 4 and Cu 2 Zn 1−x Fe x SnS 4 thin films. 50,51 The Cd 3d 3/2 and Cd 3d 5/2 peaks are located at 411.6 and 404.9 eV (Figure 2f) and can be attributed to Cd(II). The shifts of the Cu, Zn, Sn, and S spectral features and the presence of Fe and Cd peaks in the XPS spectra for the CZFCTS thin films provide further evidence for the successful introduction of Fe and Cd into the CZTS lattice.…”

Investigation of the Possibilities of Wool Fiber Surface Modification with Copper Selenide

“…Copper chalcogenides are denoted by a wide scope of application in various devices, such as solar cells, superionic conductors, photodetectors, photo-thermal converters, electroconductive electrodes, microwave shielding, coating, thermoelectric cooling, and optical filters. They also act as an optical recording material [13][14][15][16][17].…”