CIS Films Research Articles

Synthesis of CuInSe2 thin film by a hydroxides-based deposition process

CuInSe2 thin films free from In2O3 have been successfully prepared by selenization of pre-annealed Cu–In hydroxide precursors without hydrogen reduction. The mixed hydroxides of Cu, In precursors were synthesized by the co-precipitation method. The inks containing Cu–In hydroxides and organic binders were deposited onto a soda lime glass substrate using a drop-casting technique. After coating, the precursor films were pre-annealed in flowing argon prior to selenization. The influence of pre-annealing temperature on the preparation of single phase CIS films has been investigated in order to obtain single phase CIS films. Through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), it was found that chalcopyrite structure CIS films free from In2O3 were obtained in our work.

Soluble Precursors for CuInSe2, CuIn1–xGaxSe2, and Cu2ZnSn(S,Se)4 Based on Colloidal Nanocrystals and Molecular Metal Chalcogenide Surface Ligands

We report a new platform for design of soluble precursors for CuInSe(2) (CIS), Cu(In(1-x)Ga(x))Se(2) (CIGS), and Cu(2)ZnSn(S,Se)(4) (CZTS) phases for thin-film potovoltaics. To form these complex phases, we used colloidal nanocrystals (NCs) with metal chalcogenide complexes (MCCs) as surface ligands. The MCC ligands both provided colloidal stability and represented essential components of target phase. To obtain soluble precursors for CuInSe(2), we used Cu(2-x)Se NCs capped with In(2)Se(4)(2-) MCC surface ligands or CuInSe(2) NCs capped with {In(2)Cu(2)Se(4)S(3)}(3-) MCCs. A mixture of Cu(2-x)Se and ZnS NCs, both capped with Sn(2)S(6)(4-) or Sn(2)Se(6)(4-) ligands was used for solution deposition of CZTS films. Upon thermal annealing, the inorganic ligands reacted with NC cores forming well-crystallized pure ternary and quaternary phases. Solution-processed CIS and CZTS films featured large grain size and high phase purity, confirming the prospects of this approach for practical applications.

Development of sprayed CuInS2thin film absorber for nanostructured solar cell

ABSTRACTCuInS2(CIS) films were prepared by chemical spray pyrolysis (CSP) method in air using CuCl2, InCl3and SC(NH2)2as precursor materials. The effect of the absorber growth temperature in the interval of 240-350 °C and precursors’ molar ratio in the spray solution on the CIS film properties and ZnO/In2S3/CIS-type CSP-deposited thin film solar cell output characteristics has been studied. CIS films were characterized by XRD and EDX, solar cells were characterized by IV curves in dark and under illumination, and junction barrier height (Φb). The highest Φbof 1170 meV and open circuit voltage (Voc) of 560 mV were recorded for the cell with CIS absorber grown at 250 °C. Increasing the CIS deposition temperature decreases Φband Voc, makes a component of solar cell photosensitive and increases current density. The precursors’ molar ratio in spray solution becomes relevant at CIS growth temperatures higher than 300 °C as deposition of thiourea-rich solutions suppresses oxide formation in CIS layer and contributes to higher open circuit voltage.

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.

Band Gap Optimization by Ga and S Additions in CuInSe<sub>2</sub> for Solar Cell Absorber Applications

Gallium or sulphur additions in CuInSe2 were prepared using RF magnetron sputtering and pulsed laser deposition respectively. All of the observed thin films show a chalcopyrite structure with the S addition increases the favourable (112) peak. The optical absorption coefficients were slightly decreased. The films energy band gap could be shifted from 1.04 to 1.68eV by adjusting the mole ratio of S/(S+Se) and In/(In+Ga). It is possible to obtain the optimum energy band gap by adding S solute or Ga at a certain ratio in favour of Se and In respectively. It is also necessary to control the ratio of Ga and S additions and to retain a certain portion of In to provide better properties of CIS films.

Ex-situ and in-situ analyses on reaction mechanism of CuInSe 2 (CIS) formed by selenization of sputter deposited CuIn precursor with Se vapor

Formation mechanism of CIS thin films by selenization of sputter deposited CuIn precursor with Se vapor was investigated by ex-situ and in-situ phase analysis tools. Precursor films were composed of In, CuIn and Cu 2In compounds, and their relative fractions were systematically changed with Cu/In ratios. Those films were found to have a double layered structure with nearly pure In particles (top layer) placed on the flat Cu-rich bottom layer, and the morphologies were also significantly affected by Cu/In ratio. At the initial stage of selenization, the outer In-rich layer reacted with Se vapor to form In–Se binary, which is the first selenide phase appeared, and inner Cu-rich phases acted as a Cu source to supply Cu to outer In–Se phase to form ordered vacancy compounds (OVC). As these reactions continues, in conjunction with Se incorporation into inner Cu-rich region, the films gradually changes from OVC to α-CIS, reflecting that the formation route of CIS is closely related to the elemental and phase distribution in precursor films. Selenized CIS films were further processed to fabricate CIS thin film solar cells, resulting in the best cell efficiency of 10.44%.

Preparation and structure of CuInSe2 thin films for solar cells at low substrate temperatures

CIS epitaxial films were grown on (001) KCl surface with PbS sublayer and on glassceramic at 400оС. Annealing of the (α + β)-CIS films on glass-ceramic, in two-step vacuum-arc plasma discharge at 550oC provided the formation of a homogeneous large-crystalline α- CIS

Raman spectroscopy of CuIn 1 − x Ga xSe 2 for in-situ monitoring of the composition ratio

Metal organic vapor deposition (MOCVD) is a well known method for preparing high quality and large area CuIn 1 − x Ga xSe 2 (CIGS) absorber layers. Some in-situ non-contact monitoring systems are needed when CIGS absorber layers are manufactured in industry. In this study, CuInSe 2 (CIS) and CIGS thin films with different composition ratios, [Cu]/[In + Ga], were prepared by MOCVD using [Me 2In(μ-SeMe)] 2, hexafluoroacetylacetonate Cu(I) (3,3-dimethyl-1-butene), trimethyl gallium and dimethyle diselenide as the In–Se single source, Cu, Ga and Se precursors, respectively. The Raman shift spectra of the films with various composition ratios were analyzed to produce a basic algorithm that can determine the composition ratios of CIS and CIGS thin films indirectly.

Electrodeposition of Copper-Indium-Diselenide (CuInSe<sub>2</sub>) Thin Films

The electrodeposited CuInSe2 films were investigated in this paper. The deposition parameters of various solution concentrations, applied potential, pH value and complexing agent were examined to characterize film quality. The electrolyte solution was formed by mixing an appropriate proportion of copper sulfate, indium sulfate and selenium dioxide. Sodium citrate was used as complexing agent. Citric and sulfuric acids were used for adjusting electrolyte pH value. The experimental results revealed that the deposited and annealed CIS films have an atomic ratio of [Cu]：[In]：[Se] = 26.94：26.74：46.31. It is near to the stoichiometry of an atomic ratio ([Cu]：[In]：[Se] = 1：1：2). Unfortunately, this film has a poor adhesion problem. In order to overcome the adhesion problem, the triethanolamine and sodium dodecyl sulfate are used as complexing agents and wetting agents, respectively. A good adhesion was obtained. However, these additives result in a shortcoming of insufficient indium content in the formation film.

Effect of H 2S treatment on properties of CuInS 2 thin films deposited by chemical spray pyrolysis at low temperature

CuInS 2 thin films were deposited by chemical spray of aqueous solutions containing CuCl 2, InCl 3 and thiourea at substrate temperature of 250 °C in air and subjected to annealing at 530 °C in H 2S atmosphere. Structure and composition before and after annealing were studied by XRD, EDS, XPS and Raman spectroscopy. As-sprayed films were low-crystalline, showed uniform distribution of elements in film thickness and no oxygen content. For the CuInS 2 films deposited from the solutions with [Cu 2+] / [In 3+] = 1.0 and 1.1, H 2S treatment for 30 min increased the chalcopyrite content up to 73% and 51%, respectively. Cu XS phase in sprayed CIS films promotes the crystallite growth but retards the formation of chalcopyrite phase during H 2S treatment.

Morphology and crystal phase evolution of doctor-blade coated CuInSe 2 thin films

CuInSe 2 (CIS) chalcopyrite thin films were prepared using a low-cost, non-vacuum doctor-blade coating and the thermal annealing method. An acetone-based precursor solution containing copper chloride, indium chloride, selenium chloride, and an organic binder was deposited onto a Mo-sputtered soda lime glass substrate using a doctor-blade coating method. After coating, the precursor films were annealed in a quartz tube furnace under low vacuum without the use of a Se atmosphere or reduction conditions. Evolution of the morphology, crystal structure, and thermal decomposition behavior of the films was analyzed by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis, and the film formation mechanism was suggested. The as-deposited precursor film gradually decomposed with increase in temperature and formed Cu 2− x Se and In 2Se 3 nuclei on the surface of the film. Incorporation of Cu 2− x Se with In 2Se 3 yielded a chalcopyrite CIS phase, which crystallized on annealing above 400 °C. The obtained CIS film showed low-resistive ohmic behavior with a Mo electrode and a high absorption efficiency for visible–infrared (IR) light, making it suitable for use in photovoltaic applications.

CuInS 2 thin films obtained through the annealing of chemically deposited In 2S 3–CuS thin films

In this work, we report the formation of CuInS 2 thin films on glass substrates by heating chemically deposited multilayers of copper sulfide (CuS) and indium sulfide (In 2S 3) at 300 and 350 °C in nitrogen atmosphere at 10 Torr. CIS thin films were prepared by varying the CuS layer thickness in the multilayers with indium sulfide. The XRD analysis showed that the crystallographic structure of the CuInS 2 (JCPDS 27-0159) is present on the deposited films. From the optical analysis it was estimated the band gap value for the CIS film (1.49 eV). The electrical conductivity varies from 3 × 10 −8 to 3 Ω −1 cm −1 depending on the thickness of the CuS film. CIS films showed p-type conductivity.

Spray deposition of CuInS2 on electrodeposited ZnO for low-cost solar cells

Abstract CuInS 2 (CIS) thin films are deposited using chemical spray pyrolysis on top of a single (compact) and a double (compact + porous) ZnO film obtained by electrodeposition by changing the composition, pH and temperature of the bath. Conductive glass has been used as primary substrate. CIS films are deposited at 300 °C and using N 2 as carrier. A buffer layer of TiO 2 is incorporated by spray to protect the ZnO layer against dissolution during the subsequent spraying of CIS. Relevant properties, such as morphology, composition and thickness are evaluated using SEM, EDX and XRD. Also, UV–Vis analyses are carried out to assess the band gap value of CIS, resulting in 1.42 eV. Carrier densities and flat band potentials ( V fb ) are calculated from Mott–Schottky plots. The values of V fb are 0.70, 1.10 and 0.42 V for TiO 2 , ZnO and CIS respectively. I–V curves in the dark and under illumination prove that the materials can be combined to obtain solar cells. The dark response for the two devices built with single and double layers of ZnO is very similar, showing diode behavior with good rectification ratios. Under illumination, the presence of the porous ZnO improves the performance of the cell, as reflected by the higher values of photocurrent and open circuit potential.

Deposition of CuInS 2 films by electrostatic field assisted ultrasonic spray pyrolysis

We studied CuInS 2 (CIS) film growth using high electrostatic field assisted ultrasonic spray (HEFAUS) deposition. CIS films were fabricated with various precursors and substrate temperatures. All the as-sprayed CIS films were observed to be grown with mixed ordering mode, where chalcopyrite (CH) and CuAu (CA) orderings coexisted. It was found that application of additional sulfurization to sprayed CIS films induced re-crystallization of films accompanied by enhancement of CH ordering. After the post-sulfurization, the most improved film showed nearly the same CH-fraction as that for a CIS film which was made by sulfurization of sputtered Cu–In alloy film. These results indicate that our modified spray deposition could be used for fabrication of CIS photoabsorbing layer instead of high-cost vacuum-based process. All fabricated films were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscope and energy dispersive X-ray analysis measurements.

The preparation of CuInSe 2 films by solvothermal route and non-vacuum spin-coating process

A low-cost non-vacuum process for fabrication of CuInSe 2 (CIS) films by a solvothermal route and spin-coating method is described. First, the CIS precursor powders are synthesized by solvothermal technology. Second, the CIS films are deposited via spin-coating from precursor slurry consisting of CIS particles and selenization process. Through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and absorption spectroscopy measurement, the CIS nanoparticle precursors consisted mainly of plate-like particles showing the chalcopyrite structure with preferred (1 1 2) orientation. Typical near stoichiometric single phase CIS films with a micron-sized dense grains are prepared after selenization process. An energy band gap about 1.02 eV and an absorption coefficient exceeding 10 5 cm −1 are also obtained in our work.

Growth and Characterization of CIS Thin Films Prepared by Ion Beam Sputtering Deposition

Copper indium diselenide (CuInSe2) thin films were prepared by ion beam sputtering Cu, In and Se targets continuously on BK7 glass substrates and the three-layer film was then annealed in the same vacuum chamber. X-ray diffraction shows that the CuInSe2 thin films have a single chalcopyrite structure with preferential (112) orientation. Scanning electron microscopy reveals that the CIS thin films consist of uniform and densely packed grain clusters. Energy dispersive x-ray spectroscopy demonstrates that the elemental composition of CIS films approaches the stochiometric composition ratios of 1:1:2. Raman measurement shows that the main peak is at about 174 cm−1 and this peak is identified as the A1 vibrational mode from chalcopyrite ordered CuInSe2. Optical transmission and absorption spectroscopy measurement reveal an energy band gap of about 1.05eV and an absorption coefficient of 105 cm−1. The film resistivity is about 0.01 Ωcm.

The preparation of CuInSe 2 films by combustion method and non-vacuum spin-coating process

A low-cost non-vacuum process for fabrication of CuInSe 2 (CIS) films by combustion method and spin-coating process is described. First, the Cu, In oxides precursors are synthesized by combustion method, which is simpler and cheaper than the other preparation methods and is also the first applied in the CIS solar cells. Second, the CIS films are deposited via spin-coating from precursor slurry consisting of Cu, In oxides components and selenization process. Through X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS) and absorption spectroscopy measurement, it is found that Cu, In oxides precursors show the dominant CuO, In 2O 3 and Cu 2In 2O 5 phases and have a uniform distribution of the particle size. The CIS films show the dominant chalcopyrite structure, In 2O 3 and Cu 2Se phases and have a micron-sized dense gain. A typical near stoichiometric little Cu-rich CIS films is obtained. An energy band gap about 0.9 eV and an absorption coefficient exceeding 10 5 cm −1 are also obtained in our work.

Characterization of sprayed CuInS 2 films by XRD and Raman spectroscopy measurements

We studied CuInS 2 (CIS) film growth using two deposition methods, which were high electrostatic field assisted ultrasonic spray (HEFAUS) deposition and sulfurization of Cu–In metallic film. The sprayed-films were grown with chalcopyrite ordering and Cu–Au ordering mixed. In order to obtain higher quality CIS films, post-sulfurization was carried out for sprayed-films. The post-sulfurization induced improvement of crystallinity and enhancement of chalcopyrite ordering. However, it was observed that Cu–Au ordering still coexisted in the CIS film after post-sulfurization. With the same sulfurization condition, sulfurization was done to transform Cu–In metallic film into CIS film. The sulfurized metallic film was turned out to be formed as CIS film with higher crystallinity and better chalcopyrite ordering than sulfurized sprayed-films. All fabricated films were characterized by X-ray diffraction, Raman scattering, scanning electron microscope and energy dispersive X-ray analysis measurements.

Pulsed Laser Processing of Electrodeposited CuInSe2 Photovoltaic Absorber Thin Films

AbstractCuInSe2 (CIS) is commercially processed using energy intensive vacuum processes such as sputtering and thermal evaporation followed by thermal annealing. In order to reduce the cost of fabricating CIS photovoltaic absorber layers we need fast and cheap processing methods. We have investigated the use of non-vacuum electrochemical deposition (ED) followed by ultra violet pulsed laser annealing (UV-PLA). We report here on the results of ns pulsed KrF irradiation of ED CIS films and ED CIS films which were first annealed in a Se atmosphere.

Fabrication of Cu(In, Ga)Se 2 thin film solar cell absorbers from electrodeposited bilayers

CuInSe 2 (CIS) and Cu(In, Ga)Se 2 (CIGS) films as solar cell absorbers have been fabricated from electrodeposited (ED) In–Se/CIS and CIS/CuGaSe 2 (CGS) bilayers, respectively. Firstly, In–Se/CIS bilayers were intermixed by annealing at 600 °C for 10 min and it followed that CIS films with large grains and controlled compositional ratios were realized. CIS solar cells using these films showed around 2.2% efficiency. Next, CIS/CGS bilayers were annealed at 600 °C for 60 min for intermixing. Here, oxygen-free CGS films prepared from Cu–Ga–Se solution added Li 2SO 4 as the supporting electrolyte were used because Ga–O compound formed in ED-CGS films worked as the defects. As the results, around 2.9% efficiency CIGS solar cell using the films was realized. Especially, 29.7 mA/cm 2 and 36.1 mA/cm 2 high short-circuit current density were obtained in the CIS and CIGS solar cells, respectively. These results indicate that ED-bilayers technique is useful to realize low-cost and high efficiency solar cell.