Annealing Induced Shape Transformation of CZTS Nanorods Based Thin Films (original) (raw)
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Single step electrosynthesis of Cu2ZnSnS4 (CZTS) thin films for solar cell application
Electrochimica Acta, 2010
The Cu 2 ZnSnS 4 (CZTS) thin films have been electrodeposited onto the Mo coated and ITO glass substrates, in potentiostatic mode at room temperature. The deposition mechanism of the CZTS thin film has been studied using electrochemical techniques like cyclic voltammetery. For the synthesis of these CZTS films, tri-sodium citrate and tartaric acid were used as complexing agents in precursor solution. The structural, morphological, compositional, and optical properties of the CZTS thin films have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), EDAX and optical absorption techniques respectively. These properties are found to be strongly dependent on the post-annealing treatment. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained after annealing asdeposited thin films at 550 in Ar atmosphere for 1 h. The electrosynthesized CZTS film exhibits a quite smooth, uniform and dense topography. EDAX study reveals that the deposited thin films are nearly stoichiometric. The direct band gap energy for the CZTS thin films is found to be about 1.50 eV. The photoelectrochemical (PEC) characterization showed that the annealed CZTS thin films are photoactive.
Journal of Alloys and Compounds, 2021
Cu 2 ZnSnS 4 is a promising, versatile and inexpensive quaternary semiconductor with suitable optoelectronic properties for solar energy conversion. In this work, we report the synthesis of CZTS nanocrystals (NCs) using low-cost homemade hot-injection method. Oleylamine was used as both the binder and stabilizer for the CZTS NCs during the growth process. Detailed investigation of the influence of sulphur concentration and reaction temperature on the structural, stoichiometric, morphological, and optoelectronic attributes of CZTS NCs was carried out. The XRD, Raman, and TEM measurements confirm the formation of phase-pure tetragonal kesterite CZTS NCs. The synthesized CZTS NCs exhibit particle sizes in the range of 15e30 nm and display strong optical absorption in the visible region. The nearly optimal chemical composition of the CZTS NCs was confirmed by energy dispersive X-ray spectroscopy. UV eVisible spectroscopy and electrochemical measurements predict the band gap of the CZTS NCs in the range of 1.3e1.6 eV, which is very close to the optimum values for the fabrication of single junction solar cells. The estimated conduction band offset (CBO) and valence band offset (VBO) of the CZTS-3M/CdS heterostructure are predicted as 0.11 and 0.98 eV, respectively, whereas for CZTS-225 C/CdS heterostructure, CBO and VBO are 0.10 and 1.0 eV, respectively. The small conduction band offset measured at the CZTS/CdS interface are encouraging characteristics for the carrier transport and the deeper understating of band alignment and interface properties provides a hopeful approach for designing higher efficiency and more efficient carrier separation in CZTS solar cells.
ISRN Renewable Energy
The Cu2ZnSnS4(CZTS) thin films have been electrochemically deposited from a weak acidic medium (pH 4.50~5.00) onto Mo- coated and ITO-coated glass substrate by using single-step electrodeposition method. Trisodium citrate was used as a complexing agent. The effect of annealing atmospheres such as Ar, N2, N2+H2S on the structural, morphological, compositional, and optical properties of CZTS thin films has been investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and optical absorption techniques, respectively. XRD studies reveal that the as-deposited CZTS film is amorphous in nature. Upon annealing in different atmospheres, a relatively more intense and sharper diffraction peaks (112), (200), (220), and (312) of kesterite crystal structure with uniform and densely packed surface morphology are observed in N2+H2S atmosphere. Absorption study shows that the band gap energy of as-deposited CZTS thin film is 2.8 eV where...
AIP Advances
A potential solar absorber material, sputtered kesterite Cu 2 ZnSnS 4 (CZTS) thin film, has been extensively studied in recent years due to its advantageous properties, including the earth abundance of its constituent elements, nontoxicity, suitable band gap, and high absorption coefficient. 2000 nm CZTS thin films were deposited on soda lime glass by a sputtering technique. The prepared films underwent a postannealing treatment for crystallization in which different temperatures and pressures were applied to understand its impact on film growth, phase formation, and stoichiometry. The annealed samples were subsequently characterized by Raman and UV-visible (UV-Vis) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The thickness of each film was measured using a surface profilometer and from a cross-sectional image obtained by SEM. The XRD pattern for each film showed characteristic (112), (220), and (312) peaks, and the phase purity was confirmed via Raman studies. Film surface morphology and roughness were studied by AFM. The root mean square roughness was found to increase with annealing temperature and base pressure. The chemical compositions of the prepared samples were analyzed by EDX, and the films showed desired stoichiometry. UV-Vis absorption spectroscopy indicated that the direct band gap energies (Eg) of the films were 1.47 eV-1.51 eV, within the optimum range for use in solar cells. These attractive properties of the sputtered CZTS thin film should heighten interest in its use as a solar absorber layer in the next-generation photovoltaic cells, suggesting that it possesses substantial commercial promise.
Deposition of Cu 2 ZnSnS 4 (CZTS) prepared by a solution route for solar cells applications
As a promising candidate as absorber layer in thin film solar cells, the Cu 2 ZnSnS 4 (CZTS) material has gained a broad interest over recent years for the production of low-cost solar cells due to its direct and tunable band gap energy, high optical absorption coefficients and also due to the abundance and the non-toxicity of all its constituents. In addition, to solve the problem of expensive and complicated vacuum-based synthesis methods, simple and low-cost methods have been developed for the preparation of this material. In this present work, the CZTS thin films have been prepared using a solution route namely sol-gel, which is a simple and low cost method for a large production of thin films materials and spin coated onto glass substrates. The sol-gel precursor solution was made from metal salts of copper (II) chloride (CuCl 2), zinc (II) chloride (ZnCl 2), Tin (IV) chloride (SnCl 4), and thiourea (CS (NH 2) 2) dissolved into a mixture of ethanol/water as solvent. The X-ray diffraction studies showed the formation of a kesterite structure with peaks corresponding to (112) and (220) directions. The Raman spectrum indicated the presence of the principal kesterite peak at 336 cm-1 and the existence of a strange peak at 424 cm-1 which could be attributed to the binary compound Cu 2 S. The absorbance spectrum has been recorded for the estimation of the band gap. The CZTS thin film can be made using a simple spin coating technique, but improvements in the film properties by a suitable annealing time and temperature as well as annealing environment and post deposition needs have to be done for making a quality photovoltaic absorber.
Superlattices and Microstructures, 2015
Please cite this article as: A. Sagna, K. Djessas, C. Sene, M. Belaqziz, H. Chehouani, O. Briot, M. Moret, Growth, structure and optoelectronic characterizations of high quality Cu 2 ZnSnS 4 thin films obtained by close spaced vapor transport, Superlattices and Microstructures (2015), doi: http://dx.ABSTRACT High quality Cu 2 ZnSnS 4 (CZTS) thin films, as an absorber layer for thin films solar cell, were synthesized successfully using a simple and low cost technique, Close-Space Vapor Transport (CSVT). The films were grown on soda-lime glass substrates using a polycrystalline CZTS ingot as source of evaporation material. Influence of substrate temperature on chemical composition, morphological, structural, electrical and optical properties of the CZTS thin films was investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Raman spectroscopy, UV-Vis-NIR spectrophotometer, Hall effect and photoluminescence (PL) measurements. The results from XRD and Raman characterization confirmed the formation of kesterite CZTS thin films with a (112) plane preferred orientation and Raman shift of 338 cm -1 ,
Fabrication of Cu2ZnSnS4 thin film solar cell using chemical method
2011
We report the growth, characterization and fabrication of the quaternary compound semiconductor Cu2ZnSnS4 (CZTS) thin film solar cell using low temperature chemical synthesis. The constituent materials required for this ptype absorber are earth abundant and available at low cost. In addition, CZTS has large absorption coefficient in the order of 10 4 cm −1 and has optimum band-gap energy of about 1.5 eV required for an efficient photo-energy conversion. We have adopted a low temperature chemical route followed by spin coating to synthesize CZT layers. Essentially, a metal compound solution of CZT is formed by dissolving Copper (II) acetate, zinc (II) acetate and tin (II) chloride in 2-methoxyethanol and monoethanolamine. The CZT layer, which is formed by spin coating and annealing at around 300°C, is then sulphurized by using a safe organic sulphur source called di-tert-butyl-disulfide (TBDS) for a controlled sulphur transfer at temperature around 400°C to form stoichiometric Cu2ZnSnS4. The Cu to Zn+Sn and Zn to Sn ratios for an optimally synthesized film were 0.87 and 1.2 respectively. Techniques like EDX, XRD and XPS were used for composition, crystallinity and phase analysis.
Synthesis and characterization of kesterite Cu2ZnSnS4 (CZTS) thin films for solar cell application
2016
The quaternary compound Cu 2 ZnSnS 4 (CZTS) gained considerable attention in the last decade due to its potential as an active-layer semiconductor for low-cost thin-film solar cells. The material is composed of nontoxic and Earth-abundant constituents, has optical properties suitable for photovoltaic application, and can be synthesized using a wide variety of methods. Polycrystalline CZTS was grown in this work using vacuum-based deposition to first deposit metal films (precursors) of Cu, Zn, and Sn. In a subsequent step, the precursors underwent an annealing treatment in sulfur vapor environment (sulfurization) to form CZTS. Using sputtering, a physical vapor deposition (PVD) technique, two different kinds of metal precursors were deposited: a) stacked precursors, in which a stack of metal layers are sequentially deposited on a glass substrate, and b) co-sputtered precursors, in which the three metals are deposited simultaneously. The effect of sulfurization time and temperature was investigated to optimize the process and to study the impact of both factors on the morphological and structural properties of the synthesized compound. CZTS films based on a stacked precursor were prepared and characterized by X-ray fluorescence, energy-dispersive X-ray spectroscopy, electron probe microanalysis, X-ray diffraction, scanning electron microscopy , ultraviolet-visible-near-infrared spectrophotometry, and Auger electron spectroscopy. Films with dense morphology, good crystallinity, and optical energy bandgap close to Almost daily for the first year of this project, I asked myself, "Have I made the right decision?," wondering what really motivated me to work in this research area. The first answer always coming to mind was, "You're so fortunate to conduct your research at the National Renewable Energy Laboratory (NREL), one of the world's leading institutions for renewable energy research." I had come from electrical engineering to a field where people talk about film morphology, crystal structure, and many other terms new to me. So I was feeling overwhelmed, lacking relevant background and experience that I could rely on. At moments, I questioned my ability to complete this dissertation. But this journey has ultimately come to the end with the help and support of certain people to whom I am very thankful. First and foremost, I direct my thanks to my academic advisor, Prof. Mohammad Matin, for accepting me as a Ph.D. student. I also express my gratitude to Dr. Mowafak Al-Jassim for enabling me to conduct my research at NREL. My special thanks go to Dr. Helio Moutinho, who had the greatest impact on my work through valuable explanations and wide-ranging discussions. I am also appreciative to: Jeff Alleman for his ongoing help; Don Gwinner for editing my writing; Bobby To, Maikel van Hest, Jeff Blackburn, and Phil Parilla for training me on different systems; and Clay DeHart and Jeff Carapella for processing my samples into complete devices. Last but not least, I thank my family for believing in me and encouraging me to finish this task. I am thankful to my parents for supporting me in all the steps of my life. My deepest thanks go to my wife, who has always been at my side in good times and bad, and to my children for their understanding and sacrifice when it came to my work. v Table of Contents Chapter One: Introduction .