CIS Thin Films Research Articles

Influence of choline chloride pH adjuster on physical and optical properties of CuInSe2 thin films by CBD

We concentrate on low-cost thin film solar cells with the help of choline chloride acting as a pH adjuster because copper ternary material compounds and their alloys have become more and more lavish over the past 20 years. Chemical Bath Deposition (CBD) is used to produce copper indium selenium (CuInSe2) thin films on glass substrates while a pH adjuster is present. The micro structural and elemental properties are studied using X-ray diffraction (XRD), Raman, Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The optical studies of CuInSe2 thin films are done using a UV–Vis–NIR spectrometer. XRD and Raman spectra shows that the CIS thin films deposited in the sequence of Glass/In/Se/Cu2Se/Se (labeled as CISB) and annealed at 400 °C (CISB400) contains all the peaks corresponding to the chalcopyrite CuInSe2. From the EDS measurements it was noted that the selenium to metal ratio (Se/Cu + In) for all the samples changes with temperature. It is worth to note that the film thickness decreases with a decrease in the pH of choline chloride which results a change in the optical band gap of the films. The optical properties of these thin films are greatly influenced by adjusting pH and it gives better results for optoelectronic devices with a sustainable UV filter which absorbs more in ultraviolet vicinity. The energy gap (Eg) values of the CISB samples were determined and is found to be suitable for photovoltaic conversion process.

Photo-electrochemical performance of CIS and CIGS solar thin films arranged through a novel CISe/Ga-Se bilayer electrodeposition

In current work, we focused on the electrodeposition of CuInSe2 and CuIn1-xGaxSe2 by a unique two-step deposition method. Initially by a single step technique, CuInSe2 thin film was electrodeposited using an electrolyte comprised of citric acid-SDS. Further, the gallium selenium thin film was deposited on FTO substrate by potentiostatic method in tartaric electrolyte bath to get a bilayer of Ga-Se upon CISe thin film. For improving the adhesion and smoothness of electrolyth bath, sodium dodecyle sulfate has been added and it is also eliminating multinuclear growth. The CISe and CIGSe samples were further annealed at 300 0C and 525 0C in nitrogen atmosphere respectively. The structural, compositional, optical and electronic representation of as electrodeposited and annealed thin films of CISe and CIGSe were investigated by XRD, SEM and electrochemical analysis. The thin film of as electrodeposited and annealed CIS and CIGS exhibited a p-type behavior as confirmed by with photoelectrochemical (PEC) properties and by Mott-Schottky (M−S) test. By the slope and intercept values of the M−S plot, the carrier concentration and flat band values were determined. The calculated carrier concentration of as deposited and annealed CISe and CIGSe thin films are 3.70 × 1023 cm−3, 1.51 × 1024 cm−3, 9.60 × 1021 cm−3 and 7.79 × 1023 cm−3 respectively. The calculated flat band potential of as electrodeposited and annealed CISe and CIGSe thin films are 115 mV,85.48 mV, 332 mV and 58.65 mV. Here also we have done the Electrochemical Impedance Studies (EIS). The EIS were performed for as-electrodeposited and annealed CIS and CIGS thin films in the electrolyte solution to understand the charge transfer mechanism. The observed Rct values 1397 and 178.4 Ω cm2 for as-deposited and annealed CIS film and Rct values 158.2 and 81.27 Ω cm2 for as-electrodeposited and annealed CIGS thin films respectively. At a potential of −0.4 V/SCE, the obtained photocurrent density for as deposited and annealed CISe and CIGSe thin films by PEC test are 1.10 × 10−4 A cm−2, 1.35 × 10−4 A cm−2, 1.07 × 10−4 A cm−2 and 3.01 × 10−4 A cm−2 respectively.

Self-aggregation, H-bonding, and photoresponse in film and solution states of azobenzene containing polyurea.

We critically understand the hydrogen bonding interactions and electronic transitions occurring in a thin film as well as in solution of a photo-responsive polymer, azo-polyurea (azo-PU). We synthesize azo-PU by covalent attachment of the azobenzene chromophore to the main chain of polyurea. Azo-PU shows reversible photoisomerization between trans and cis states upon light exposure, the occurrence of which is typically analysed using the π-π* and n-π* electronic transition peaks in the UV-visible absorption spectrum. We find that the π-π* and n-π* bands undergo a redshift and blueshift respectively on dissolving azo-PU in DMF solvent, resulting in a single overlapped peak in the spectrum. However, upon UV irradiation, these bands split into two independent transitions that are characteristic of azo-PU solid films. These observations are explained based on the changes in polymer-polymer and polymer-solvent interactions through hydrogen bonding and self-aggregation tendency. The experimental findings are corroborated using DFT simulations which provide useful insights into electronic orbital transitions, electron distribution, and hydrogen bonding interaction through IR vibrational modes.

Metastable (CuAu-type) CuInS2 Phase: High-Pressure Synthesis and Structure Determination.

We report on the high-pressure solid-state synthesis and the detailed structural characterization of the metastable, CuAu-type CuInS2 (CA-CIS) phase. Although often present in CIS thin films as unwanted phase, it has been never synthesized in pure form, and its effect on the performance of CIS-based solar cells has been long debated. In this work, pure CA-CIS phase is synthesized in bulk polycrystalline form through a high-pressure-high-temperature solid-state reaction. Single-crystal X-rays diffraction reveals the formation of tetragonal CA-CIS (a = 3.9324(5), c = 5.4980(7) Å) either in cation-ordered and disordered phase, pointing out the role of the pressure/temperature increase on the Cu/In ordering. The resistivity measurements performed on CA-CIS show low resistivity and a flat trend vs temperature and, in the case of the ordered phase, highlight a bad-metallic behavior, probably due to a high level of doping. These findings clearly rule out the possibility of a beneficial effect of this phase on the CIS-based thin film solar cells.

The influence of Ag doping and annealing on phase, structural and carrier transport characteristics of CIS thin films

Abstracts The un-doped and Ag-CIS thin films were deposited on quartz glass substrates by single source thermal evaporation method. Then, some CIS films were annealed in vacuum or N2 atmosphere from 350 °C to 550 °C. The results of XRD patterns showed the phase compositions of CIS thin films were changed with the increase of annealing temperature. Meanwhile, the results of Raman measurement confirmed a dramatic transition from CA phase to CH phase. Furthermore, the Ag atoms could promote the recrystallization process and the transition from CA phase to CH phase, which might result in the improvement of optical-electrical properties of CIS film. The transient photocurrent of the CIS-3 sample annealed at 450 °C was higher than those of other samples, which might be related to the good crystal quality. The results of I-V curves confirmed the N-type conduction of CIS-3 films, which was consistent with the results of EDS measurement. The C-V results of CIS-2 films also were the same as the results of EDS measurement. Furthermore, for the CIS-2 samples, with increase of annealing temperature, the change of conduction type may be related to the S element volatilization under vacuum situation and the decomposition of the substitutional defects AgIn.

Preparation and Characterization of Cis Thin Films Obtained by Electrodeposition onto Ito and Mo Substrates

Preparation and Characterization of Cis Thin Films Obtained by Electrodeposition onto Ito and Mo Substrates

Preparation of perfect chalcopyrite ordering CuInS2 thin films by high-temperature sulfurization of metal oxide nanoparticles

In this letter, a low-cost non-vacuum process is introduced to fabricate the pure crystalline chalcopyrite (CH) CuInS2 thin films. Since the Chalcopyrite (CH) and CuAu (CA) ordering phases have very close formation energy and structures and tend to coexist in CIS films, it is very difficult to get single-phase chalcopyrite CIS in normal way. Simply, in this study, the high-temperature sulfurization of copper indium oxide nanoparticles precursor layers has been taken out and the presence of the metastable CuAu (CA) ordering phase is successfully avoided in the chalcopyrite CIS thin films. In addition, films sulfurized at high temperature show pure chalcopyrite phase, good crystallization and reliable optical properties, which are suitable for preparation of high efficiency solar cells.

CuInSe2 thin film solar cells prepared by low-cost electrodeposition techniques from a non-aqueous bath

Highly crystalline and stoichiometric CIS thin films have been electrodeposited from non-aqueous bath at temperature 130 °C. Superstrate solar cell structure (FTO/CdS/CIS/Au) exhibited 4.5% power conversion efficiency.

Progress in CIS Series Thin Films Solar Cells

Advances in the preparation and research of CuInSe2thin films solar cell are reviewed. The main attention is given to the effects of synthesis methods, including sputtering, spray pyrolysis, thermal evaporation, electrodeposition, dissolution-spin coating. And the structures, morphologies, compositions and photoelectrical performances of the CIS thin films synthesized by different methods are compared. The defects of different methods and research direction in the future were discussed.

Fabrication of Nanostructured Copper Indium Diselenide (CIS) Thin Films by Electrohydrodynamic Atomization Technique

In this article, we report a non-vacuum electrohydrodynamic atomization (EHDA) technique for deposition of CulnSe2 (CIS) thin films. The CIS ink has been prepared with three different concentrations (7.5 wt.%, 12.5 wt.% and 15 wt.%) by using suitable solvent mixture (ethanol:terpineol as 1:1 molar ratio) with surfactant to achieve a stable dispersions. The important physical parameters for achieving homogeneous with non-agglomerated CIS layers through EHDA technique are investigated in detail. The X-ray diffraction pattern confirms the crystalline structure of CIS layers oriented in the chalcopyrite phase. The film uniformity has been investigated by field emission scanning electron microscopy. Different thickness of CIS layers has been achieved by varying the concentration of CIS particles in the precursor ink solution. The optical properties of CIS layers show the two optical band gaps in UV-visible and near infra-red (NIR) region with band gap of about 2.67-2.49 eV and 1.34-1.29 eV respectively. The energy band gap of CIS thin films have been decreased with the increase of film thickness. The X-ray photoelectron spectra confirmed presence of binding energy corresponding to CulnSe2. The electrical study observed the sheet resistivity 76-33 Omega cm with respect to film thickness.

Cyclic Voltammetry Study on Electrodeposition of CuInSe2 Thin Films

Chalcopyrite (CIS) is considered to be an effective light-absorbing material for thin film photovoltaic solar cells. CIS thin films have been electrodeposited onto Mo coated and ITO glass substrates in potentiostatic mode at room temperature. The deposition mechanism of CIS thin films has been studied using the cyclic voltammetry (CV) technique. A cyclic voltammetric study was performed in unitary Cu, In, and Se systems, binary Cu-Se and In-Se systems, and a ternary Cu-In-Se system. The reduction peaks of the ITO substrate were examined in separate , , and solutions. Electrodeposition experiments were conducted with varying deposition potentials and electrolyte bath conditions. The morphological and compositional properties of the CIS thin films were examined by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The surface morphology of as-deposited CIS films exhibits spherical and large-sized clusters. The deposition potential has a significant effect on the film morphology and/or grain size, such that the structure tended to grow according to the increase of the deposition potential. A CIS layer deposited at -0.6 V nearly approached the stoichiometric ratio of . The growth potential plays an important role in controlling the stoichiometry of CIS films.

MAPLE-based method to obtain biodegradable hybrid polymeric thin films with embedded antitumoral agents

In this work, antitumor compounds, lactoferrin [recombinant iron-free (Apo-rLf)], cisplatin (Cis) or their combination were embedded within a biodegradable polycaprolactone (PCL) polymer thin film, by a modified approach of a laser-based technique, matrix-assisted pulsed laser evaporation (MAPLE). The structural and morphological properties of the deposited hybrid films were analyzed by Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The in vitro effect on the cells' morphology and proliferation of murine melanoma B16-F10 cells was investigated and correlated with the films' surface chemistry and topography. Biological assays revealed decreased viability and proliferation, lower adherence, and morphological modifications in the case of melanoma cells cultured on both Apo-rLf and Cis thin films. The antitumor effect was enhanced by deposition of Apo-rLf with Cis within the same film. The unique capability of the new approach, based on MAPLE, to embed antitumor active factors within a biodegradable matrix for obtaining novel biodegradable hybrid platform with increased antitumor efficiency has been demonstrated.

Synthesis of CIS Nanoink and Its Absorber Layer without Selenization

Highly crystalline CIS nanoink was synthesized using highly efficient microwave route. Thin films of CIS were fabricated using the developed ink by drop casting method. XRD pattern of CIS thin films indicates that a chalcopyrite phase with good crystallinity can be obtained using developed ink and that the composition of precursor ink can be transferred directly to the thin film without change in the stoichiometry. The developed ink alleviates the need of organic binders/dispersant and high temperature selenization using highly toxic H2Se gas (or Na2Se as a Se source) after deposition of thin film absorber layer. UV-VIS-NIR absorption analysis indicates that CIS thin film has a band gap of around 1.18 eV.

Band gap engineering of tandem structured CIGS compound absorption layer fabricated by sputtering and selenization

Band gap engineering was executed to fabricate a multi-junction stacked i.e. tandem Cu(In,Ga)Se2 (CIGS) absorption layer. The CIGS absorption layers consist of multi-junction stacked CIS/CIGS/CGS thin films from bottom to top with increasing band gap. Tandem CIGS layers were fabricated by using three precursor of CuIn, In/CuGa/In, and CuGa onto the Mo coated soda-lime glass (SLG) by the sequential sputtering of CuIn, CuGa, and In targets. The CIG precursors were converted into CIGS absorption thin film by selenization process. From the X-ray diffraction (XRD) pattern of CIS/CIGS/CGS tandem layer, with the prominent peak shift for (112) reflections was attributed to the individual CIS, CIGS, and CGS phases at 26.76°, 27.15°, and 27.65° diffraction angles, respectively. The morphologies and atomic (at%) composition uniformity onto the surface and along the depth were extensively analyzed with field effect scanning electron microscope (FESEM) attached energy dispersive spectroscopy (EDS) and secondary ion mass spectroscopy (SIMS). The optical properties such as transmittance, reflectance and absorbance were found to improve in the infrared region for all the tandem CIGS layers. Near the fundamental absorption edge, the absorption coefficient was approached to 105cm−1 for CIS/CIGS/CGS tandem layer. The straight-line behavior indicates that the films have a direct band gap. The band gap was found to increase from 1.15 to 1.74eV with the Ga-grading along the depth of individual CIS, CIGS, and CGS thin films. In the tandem CIGS layer, consist of CIS/CIGS, CIS/CGS, and CIS/CIGS/CGS thin films, the band gap was further increased from 1.42 to 2.06eV, respectively. Such band gap engineering in CIGS tandem absorption layer will be a stepping stone to further improve the solar cell performance.

Pulsed Electrodeposition of CuInSe2 Thin Films with Morphology for Solar Cell Applications

Copper indium diselenide (CuInSe2) films have been prepared by pulse electrodeposition technique on Molybdenum substrate followed by post-deposition annealing at 550°C. Optimization of pulse parameters by varying the pulse duration (duty cycle) in order to achieve high quality films has been reported. Appropriate manipulation of pulse parameters has resulted in a novel flake-like crystallite morphology and better control over the composition of individual elements. The CIS thin films were comprehensively characterized using SEM-EDS, FIB, XRD and UV-DRS to study their morphology, phase constitution, etc. and PEC (photoelectrochemistry) measurements were also carried out to ascertain the photoelectrochemical performance of the CIS absorber layer. The bandgap of the CIS films was determined to be 1.02 eV. The flake like crystallite morphology observed in CIS thin films under the optimized processing conditions was found to yield enhanced cathodic photoresponse under solar simulated light with a photocurrent density of 20 μA/cm2 (observed at a potential of −0.6 V vs. SCE). The films exhibited a photoresponse typical of a p-type semiconductor.

Synthesis and Characterization of CIS Thin Film Using Chloride Solution

 Abstract—In this study, manufacturing cost reduced for CIS precursor solution from chloride series CuCl2, InCl3, GaCl3 mixed with acetone solvent without binder was discussed. CIS thin films were coated on a substrate using this precursor solution prepared at normal temperature and pressure by Doctor Blade method. We observed that CIS crystals began to form on the surface at 300° C and the surface and internal faults were growing with increasing the temperature. The intensity of main peak increased in CIS absorber layer.

Solvothermal synthesis of nanostructured CuInS2 thin films on FTO substrates and their photoelectrochemical properties

This study reports the growth of CIS nanosheets and nanoworms on FTO glass through a surfactant-assisted solvothermal process. The as-prepared products are single crystalline in tetragonal structure with the crystal lattice spacing of about 0.32 nm which agrees with the (112) plane of CIS. The formation process is investigated and a possible growth model is proposed. Both oxalic acid and CTAB are found to play important roles during the formation process of the CIS thin films. Raman analysis reveals that the film quality can be simply adjusted by changing the ratio of the reactants and that higher content of TU will lead to better crystallinity. The direct band gap values of the CIS nanosheets and nanoworms are calculated to be 1.50 and 1.55 eV, respectively. Both values are very close to that of bulk CIS (1.53 eV). The PEC properties of the CIS nanosheets and nanoworms are studied as well. Compared with the nanosheet electrode, these nanoworms synthesized in sulfide-rich environment exhibit better photoelectric performance due to their better visible-light absorption and improved film conductivity.

Optical Properties of \(\text{CuInS}_{2}\) Thin Films Prepared by Spray Pyrolysis

Polycrystalline CuInS\(_{2}\) (CIS) absorber films for solar cells were prepared by spray pyrolysis of aqueuos solution of copper chloride, indium chloride and thiourea onto heated glass substrates. By optimizing the spray parameters, such as reducing/increasing the temperature of the substrate and molar ratio of Cu/In in the spraying solution, the optical characteristics of films, which are well matched to the solar spectrum, were identified. In all cases, those CIS thin films were of p-type conductivity. Transmission measurements were performed to examine the optical properties of the films; the absorption coefficient and the optical band gap of the films were calculated by transmission spectra. The absorption spectra of the films showed that this compound is a direct band gap one and its gap varied between 1.30 - 1.78 eV. Those thin films were analyzed by X-ray diffraction in order to understand the effect of layers structure on their optical properties.

Low cost CuInSe 2 thin films production by stacked elemental layers process for large area fabrication of solar cell application

Low cost deposition of large area CuInSe 2 (CIS) thin films have been grown on Mo-coated glass substrate by simple and economic stacked elemental layer deposition technique in vacuum. The grown parameters such as concentration of Cu, In and Se elements have been optimized to achieve uniform thin film in vacuum chamber. The as-grown Cu/In/Se stacked layers have been annealed at 200 °C and 350 °C for 1 h in air ambient. The as-grown and annealed films have been further subjected to characterization by X-ray diffraction (XRD), optical absorption, atomic force microscopy (AFM) and I– V measurement techniques. XRD patterns revealed that as-grown Cu/In/Se stacked layers represent amorphous nature while annealed CIS film reproduces nano-polycrystalline nature with chalcopyrite structure. The optical band gap of annealed films increases with respect to air annealing which confirms the reduction of crystallite size. Surface morphology of as-grown Cu/In/Se stacked layers and annealed CIS thin films have been confirmed by AFM images. The electrical measurements show enhancement of conductivity which is useful for solar cell application.

Preparation and characteristics of CuInSe 2 thin films by dip-coating method using its nanocrystal ink

Nanocrystal ink-coating technique is a low cost, less pollution, and non-vacuum solution based processing to produce CIS absorbing layers for photovoltaics, leading to low fabrication cost and eco-friendly process of solar cells. In this work, highly crystallized chalcopyrite CuInSe 2 (CIS) nanocrystals were synthesized by a green and cheap air pressure hot injection method using 1-Methyl-2-pyrrolidinone and glycerol mixed solvent, and copper chloride, indium chloride and selenium dioxide as precursors. The synthesized CIS nanocrystals were used to prepare colloidal nanocrystal inks by dispersing them ultrasonically in absolute alcohol and deposit CIS thin films by dip-coating nanocrystal inks. Basic characterization data of the synthesized CIS nanocrystals and the ink-coated thin films were described by XRD, TEM, FESEM, EDS, UV–vis–NIR, and Hall measurements.