Cu2ZnSnS4 Thin Films Research Articles

Growth and characterization of spray-deposited Cu2ZnSnS4 thin films by using two different carrier gases

Cu2ZnSnS4 is a promising renewable energy thin film semiconducting material used in heterojunction solar cells. These films have been deposited at the optimized condition of the spray pyrolytic technique. Compressed air and nitrogen are used as carrier gases for the deposition of the films. The X-ray diffraction studies and micro-Raman analysis confirm the structure of these films as kesterite. The crystallinity of the films depends on the nature of the carrier gas. The microstrain and dislocation density in the films is found to decline when the films deposited with nitrogen are used as carrier gas. The optical studies confirm these materials exhibit a direct band gap and are close to 1.53 eV. The material shows p-type conductivity. A heterojunction Cu2ZnSnS4 thin film solar cell is fabricated using simple chemical methods and this cell shows a maximum efficiency of about 0.8%.

12.3% Efficient Low Voc Loss Pure Sulfide Kesterite Solar Cells from DMSO Solution via Cadmium Alloying

AbstractCd alloying has been theoretically proved to be an effective strategy to suppress Cu‐Zn antisite defects and related defect cluster for improving device performance of pure sulfide kesterite Cu2ZnSnS4 (CZTS) thin film solar cells. However, the potential of Cd alloying has not been fully realized by solely doping without further post heat‐treatment. Here, Cd alloying CZTS (Cu2(Zn,Cd)SnS4, CZCTS) is reported through dimethyl sulfoxide (DMSO) solution and how alloying concentration affects reaction path, grain growth, and electronic properties of the CZCTS absorbers is investigated. This study found that Cd can be incorporated into CZTS through direct phase transformation grain growth, which sufficiently suppresses band tailing. High quality CZCTS absorber films and efficient solar cells are fabricated within a wide range of alloy concentration. A champion CZCTS device with a power conversion efficiency of 12.3% is achieved at 35% Cd concentration without any post heat treatment, improved by over 70% compared to 7.0% of CZTS. This device exhibits a high VOC gain to the Shockley–Queisser (Voc/VocSQ = 59.7%), the lowest VOC deficit achieved in pure sulfide kesterite solar cells. The results demonstrate the importance of the Cd alloying strategy for mitigating band tailing and achieving high efficiency pure sulfide kesterite solar cells.

Investigation of nucleation and growth mechanism of Cu2ZnSnS4 absorber layer electrodeposition on Indium Tin Oxide coated glass

In this paper, earth-abundant and environmentally friendly kesterite Cu2ZnSnS4 (CZTS) thin films are successfully synthesized by electrodeposition on Indium Tin Oxide (ITO) coated glass for photovoltaic application. For the first time, the electrochemical nucleation and growth mechanisms of the kesterite electrodeposition are investigated. Here, the electrochemical growth mechanism is studied and the diffusion coefficient D is calculated for different applied potentials. Our findings show that kesterite deposition occurs through progressive nucleation followed by the limited growth of diffusion of 3D hemispheric islands. Furthermore, it has been proven that the type of nucleation and growth is not influenced by the applied potential. Scanning electron microscopy, X-ray diffraction and UV–vis are used to characterize the physicochemical properties of the prepared samples. The morphological and crystallographic investigations reveal a different morphology and structure of the CZTS film deposited at different potentials for different times. Among the samples studied, the CZTS thin film prepared at −1.1 V for 60 min offers the best properties with 2.4 µm thickness after annealing at 450 °C.

Structure of Ag-Containing Cu2ZnSnS4 Thin Films, Obtained by Spray Pyrolysis

Structure of Ag-Containing Cu2ZnSnS4 Thin Films, Obtained by Spray Pyrolysis

Investigating the effects of bismuth doping on the structural, optical, and electrical properties of Cu2ZnSnS4 thin films for photovoltaic applications

Investigating the effects of bismuth doping on the structural, optical, and electrical properties of Cu2ZnSnS4 thin films for photovoltaic applications

Influence of Inter-Molar Concentration of Cu and Zn on the Various Properties of Sprayed Nano-Crystalline Cu2ZnSnS4 Thin Films

In this work, the quaternary nanostructured Cu2ZnSnS4 (CZTS) thin films were deposited on ITO glass substrates at a temperature of 300[Formula: see text]C by spray pyrolysis method and the influence of inter-molar concentration variations of copper and zinc on the structural, morphological and optical properties of grown samples was studied. The films were characterized by different sophisticated techniques including X-ray diffractometer (XRD), scanning electron microscopy (SEM), Raman spectroscopy and UV–Vis spectroscopy. The solitary presence of kesterite tetragonal phase with favored orientation along (112) plane is confirmed by XRD patterns and Raman spectroscopy. However, due to the variation in lattice parameters, a moderate shifting in (hkl) planes was observed. SEM micrographs and EDAX analysis showed the uniform morphology of the so-grown CZTS films covered with nanoplates of different sizes and the ionic compositional variation of the precursor solution matches with the elemental variation in the grown samples. A minor nonstoichiometry in chemical composition ratio [Formula: see text] from 0.74 to 1.24 was noticed in the films. Optical studies of CZTS films showed that these films possess optical band gap ranging from 1.45[Formula: see text]eV to 1.60[Formula: see text]eV.

Elaboration by spin coating and characterization of CZTS films

Thin films of Cu2ZnSnS4 (CZTS) were deposited by the sol-gel spin coating method from a non-aqueous solution containing different molarities of precursors, cupric chloride CuCl2 (2H2O) (2M), zinc chloride ZnCl2 (1M), stannic chloride SnCl2 (2H2O) (1M) and thiourea SC(NH2)2 (8M) dissolved in different volumes of solvents, methanol CH3OH and deionized water. A light-yellow solution was formed by thermal centrifugation at adjustable speeds for several minutes. Characterizations were carried out after deposition, drying and thermal annealing of these films. XRD spectra showed the formation of several peaks with one peak corresponding to the (112) directions illustrating the presence of kesterite. The gap energy was deduced 1.87 eV from the transmittance obtained by UV-Visible-NIR. The percentages of the different CZTS constituents by SEM were recorded. The thicknesses of the films obtained by profilometer are between 0.6 μm and 2 μm. The theoretical study and the results of the characterization can contribute to the realization of a CZTS active layer of a photovoltaic cell.

Growing Cu2ZnSnS4 Thin Film at Low Temperature Using a New Improved Configuration of Close‐Distance CVD Technique

AbstractThis study presents a new possibility to deposit the polycrystalline Cu2ZnSnS4 (CZTS) thin film at low temperature using an improved close‐distance chemical vapor deposition reactor. Firstly, a theoretical study is conducted to predict the iodine pressure (PI2) and the substrate temperature (Ts) as the optimal conditions for the deposition of CZTS. The theoretical model is based on the minimization of the Gibbs energy of the Cu‐Zn‐Sn‐S‐I chemical system. An experimental study is realized, and the predicted optimal conditions to obtain quasi‐stoichiometric depositions are tested. The X‐ray diffraction, Raman spectroscopy, energy dispersive spectroscopy, scanning electron microscopy, and UV–vis–NIR spectroscopy are used to analyze the thin films elaborated at substrate temperatures of Ts = 400 and 550 °C for iodine pressure PI2 = 0.03 × 105 Pa. With the help of the thermodynamical calculations, the results show that it is possible to grow a good quality CZTS thin film at a low substrate temperature of 400 °C.

Effects of Cu+ ion implantation on band gap and Raman shift of Cu2ZnSnS4 thin films

In this study, shifts in the band gap and position of the main Raman peak of Cu2ZnSnS4 (CZTS) thin films were analyzed. These shifts were caused by residual tensile strain originating from artificially implanted Cu+ ions on the CZTS thin films. Cu+ ions were implanted at various doses in the CZTS thin films. The residual strain increased linearly as the logarithmic dose of Cu+ ions increased. According to the Raman spectrum analysis, the CZTS thin films had kesterite order structures. The band gap and the shift of the main Raman peak, P1, are linear functions of the residual strain and are linearly related to each other. A larger residual strain led to larger decreases of 1.50 eV and 337.5 cm−1 in the band gap and position of the main Raman peak (P1), respectively.

Characterization of the CZTS (Cu2ZnSnS4) thin film for solar cell absorber layer synthesized from the nitrate-based sol-gel precursor solution

Manufacture of eco-friendly CZTS (Cu2ZnSnS4) thin film absorption layer of pure keserite structure for solar cell is far-reaching. We have manufactured the CZTS thin films by sol-gel dip-coating means from the nitrate-based chemicals. After hardening at 550°C in vacuum condition, we characterize the films by UV–vis spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) methods. The CZTS films provided high optical absorption coefficient (2.92x104cm-1) and average band gap energy (1.58 eV). X-ray diffraction analysis proved the kesterite structure of films. The surface morphology analysis proved the deposition of crammed, condensed and granulated CZTS films. The thin films have intermittent disposal of agglomerated particles with clear-cut edges. The energy dispersive X-ray spectroscopy analysis conferred stoichiometric ratio as Cu: Zn: Sn: S= 2.1: 1.3: 1: 5.2. DUJASE Vol. 7 (2) 1-7, 2022 (July)

Simplest synthesis and characterization study of flower-like Cu2ZnSnS4 thin films

Nowadays Cu2ZnSnS4 (CZTS) thin film is most reliable as economical and eco-friendly semiconductor material due to having advantageous properties likes high absorption coefficient and optimum band gap. Addition to these CZTS has nontoxic elements and naturally abundant readily available. Here we report economical and simplest chemical bath deposition method to synthesis of Cu2ZnSnS4 thin films which were studied by characterization techniques like XRD, Raman, UV–Visible spectroscopy, electrical conductivity, scanning electron microscopy techniques by which we report poly-crystalline CZTS thin films having stable kasterite structure in a excellent stoichiometric with 1.45 eV as an ideal band gap and its SEM reports uniform typical flower -like morphology.

Structural and morphological properties of RF sputtered Cu2ZnSnS4 thin film for solar cell application

Structural and morphological properties of RF sputtered Cu2ZnSnS4 thin film for solar cell application

Development of different characterizations of sprayed Cu2ZnSnS4 thin films: a review

Development of different characterizations of sprayed Cu2ZnSnS4 thin films: a review

Impact of 1,8-Diiodooctane (DIO) Additive on the Active Layer Properties of Cu2ZnSnS4 Kesterite Thin Films Prepared by Electrochemical Deposition for Photovoltaic Applications

Kesterite Cu2ZnSnS4 (CZTS) thin films using various 1,8-diiodooctane (DIO) polymer additive concentrations were fabricated by the electrochemical deposition method. The optical, electrical, morphological, and structural properties of the CZTS thin films synthesized using different concentrations of 5 mg/mL, 10 mg/mL, 15 mg/mL, and 20 mg/mL were investigated using different techniques. Cyclic voltammetry exhibited three cathodic peaks at -0.15 V, -0.54 V, and -0.73 V, corresponding to the reduction of Cu2+, Sn2+, Sn2+, and Zn2+ metal ions, respectively. The analysis of the X-ray diffraction (XRD) pattern indicated the formation of the pure kesterite crystal structure, and the Raman spectra showed pure CZTS with the A1 mode of vibration. Field emission scanning electron microscopy (FE-SEM) indicated that the films are well grown, with compact, crack-free, and uniform deposition and a grain size of approximately 4 µm. For sample DIO-20 mg/mL, the elemental composition of the CZTS thin film was modified to Cu:Zn:Sn: and S = 24.2:13.3:12.3:50.2, which indicates a zinc-rich and copper-poor composition. The X-ray photoelectron spectroscopy (XPS) results confirmed the existence of Cu, Sn, Zn, and S elements and revealed the element oxidation states. The electrochemical deposition synthesis increased the absorption of the CZTS film to more than 104 cm-1 with a band gap between 1.62 eV and 1.51 eV. Finally, the photovoltaic properties of glass/CZTS/CdS/n-ZnO/aluminum-doped zinc oxide (AZO)/Ag solar cells were investigated. The best-performing photovoltaic device, with a DIO concentration of 20 mg/mL, had a short-circuit current density of 16.44 mA/cm2, an open-circuit voltage of 0.465 V, and a fill factor of 64.3%, providing a conversion efficiency of 4.82%.

Improved performance of Cd-free CZTS thin-film solar cells by using CZTS0.4Se0.6 BSF layer

Cu2ZnSnS4 (CZTS) thin film solar cells (TFSCs) have received great attention from the solar cell industry for their environment, price, high absorption coefficient and great electronic properties. This work provides a strategy to prompt the photoelectric conversion efficiency (η) of CdS/CZTS-based TFSCs via introducing the back surface field (BSF) layer and wxAMPS to simulate the results. Meanwhile, the optimum ratio of sulfur to selenium in the BSF layer material CZTSSe has been also studied, and a new device structure has been constructed. Beneficial from the introduction of CZTSSe as a BSF layer, the interface recombination is suppressed and leads to an enhanced Voc. Subsequently, MoO3, ZnS, WO3, TiO2 and In2S3 as candidates to substitute for the toxic Cd buffer layer are investigated. The results demonstrate that In2S3/CZTSSe exhibits the best performance with 28.59 % and 0.99 V, ascribed to a superior spike-like value. It was found that the presence of a spike-like conduction band (CB) at the In2S3/CZTSSe interface and a more suitable conduction band offset (CBO) value could suppress the interfacial complexation. Therefore, In2S3 performs best as a buffer layer material. However, due to the cost of indium, this paper recommends the utilization of wide bandgap semiconductor materials MoO3 and ZnS, which also have good stability and conversion efficiencies that can reach 28.38% and 28.41%, respectively. The work of this paper provides important guidance for researchers to manufacture CZTS TFSCs.

CuSCN Modified Back Contacts for High Performance CZTSSe Solar Cells

AbstractOptimization of the back contact interface is crucial for improving the performance of Cu2ZnSnS4 (CZTS) thin film solar cells. In this paper, self‐depleted CuSCN is deployed as an intermediate layer at the Mo/CZTS interface to improve the quality of the back contact. This CuSCN layer, obtained via aqueous solution processing, reduces the thickness of Mo(S,Se)2 and eliminates multi‐layer crystallization of the absorber by suppressing the undesirable reaction between Mo and Se during the selenization process. By regulating the selenium infiltration into the CZTS precursor films during the selenization process, highly crystalline, single‐layer Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers are realized. The single‐layer CZTSSe absorber exhibits reduced carrier recombination, enhanced carrier density and increased work function. The improved back contact and absorber layer enables 11.1% power‐conversion‐efficiency to be achieved.

Investigation of photocatalytic activity (under visible light) of ultrathin CZTS films produced in different thicknesses by PLD method

Cu2ZnSnS4 (CZTS) thin films in 61 nm, 112 nm, 242 nm and 313 nm thickness which have been produced by Pulsed Laser Deposition (PLD) on Soda Lime Glass substrates as a function of the number of laser pulses. As the deposition of ablated material has been augmented with increasing number of laser pulses, it has been noticed that CZTS-ultrathin film’s thicknesses and particle sizes have been increased, their crystalline structures have been improved. Larger particles limit the transmission of light and cause thin films to absorb photons. The band gaps of CZTS (61 nm), CZTS (112 nm), CZTS (242 nm) and CZTS (313 nm) thin film which have been determined to be 1.95 eV, 1.90 eV, 1.50 eV and 1.45 eV, respectively. CZTS (61 nm) ultrathin film with the thinnest one among the thin films produced in this work, which is Cu and S poor but Sn and Zn rich. By increasing the thickness of the film, it has been observed that the amount of Cu and S were increased, and the ratio of Sn and Zn were decreased. In addition, it has been systematically investigated that the photocatalytic activity of the ultra-thin CZTS films coated in different thicknesses by PLD method. Among all the photocatalysts, the CZTS (in 242 nm thickness) photocatalyst has exhibited the highest photocatalytic performance, managing to remove 96.1% of methylene blue (MB) in 240 min. Furthermore, the mechanism that performs photocatalysis has been investigated by scavenger experiments, and it was observed that \({}^{ \cdot }O_{2}^{ - }\) radical ions have an important role in the reaction, while holes have little effect.

Enhanced photoresponse of Cu2ZnSnS4 absorber thin films fabricated using multi-metallic stacked nanolayers.

Cu2ZnSnS4 (CZTS) thin films have attracted considerable attention as potential candidates for photovoltaic absorber materials. In a vacuum deposition technique, a sputtering stacked metallic layer followed by a thermal process for sulfur incorporation is used to obtain high-quality CZTS thin films. In this work, for fabricating CZTS thin films, we have done a 3LYS (3 layers), 6LYS, and 9LYS sequential deposition of Sn/ZnS/Cu metal stack (via. metallic stacked nanolayer precursors) onto Mo-coated corning glass substrate via. RF-sputtering. The prepared thin films were sulfurized in a tubular furnace at 550 °C in a gas mixture of 5% H2S + 95% Ar for 10 min. We further investigated the impact of the Sn/ZnS/Cu metal stacking layers on the quality of the thin film based on its response to light because metal inter-diffusion during sulfurization is unavoidable. The inter-diffusion of precursors is low in a 3-layer stack sample, limiting the fabricated film's performance. CZTS films with 6-layer and 9-layer stacks result in an improved photocurrent density of ∼38 μA cm-2 and ∼82 μA cm-2, respectively, compared to a 3-layer sample which has a photocurrent density of ∼19 μA cm-2. This enhancement can be attributed to the 9-layer approach's superior inter-diffusion of metallic precursors and compact, smooth CZTS microstructure evolution.

Tailoring the electrical properties of Cu2ZnSnS4 thin film by heterovalent Al3+ doping

Kesterite Cu2ZnSnS4 (CZTS) thin film is an attractive photovoltaic material. Harmful vacancy and anti-site defects in CZTS can be reduced by equivalent doping. However, equivalent doping leads to a reduction in the carrier concentration that is essential to the built-in electric field and built-in potential of the device. In this work, we propose heterovalent Al doping to provide hole conduction in CZTS thin film. The chemical valence of doping cation Al3+ is different from that of the substituted cation Sn4+. Al-doped CZTS thin films were fabricated by magnetron sputtering and sulfurization. The Al content was controlled by the Al sputtering time of the precursor. The experimental results revealed the successful fabrication of heterovalent Al-doped CZTS with the preferred orientation of the (112) plane. The partial substitution of Sn by Al led to a right shift of the CZTS diffraction peaks. Al doping could improve the crystalline quality of CZTS, reduce the dislocation density and microstrain of CZTS, and enhance the compactness of the thin-film surface. With the increase in Al content, the distance decreased between the Fermi level and the valence band maximum of CZTS, and the hole concentration and conductivity of CZTS increased monotonously while the non-radiative recombination of carriers was suppressed. The conductivity of CZTS reached 1.47 × 102 S/cm. Therefore, heterovalent Al doping was found to be a useful method to regulate the electrical properties of CZTS thin film.

Comparative Study between Spin Coated Cu2ZnSnS4 and Cu2FeSnS4 Thin Films for Thin-Film Solar Cell Applications

Comparative Study between Spin Coated Cu2ZnSnS4 and Cu2FeSnS4 Thin Films for Thin-Film Solar Cell Applications