CuInS2 Particles Research Articles

Water Phase Synthesis Method of CuInS2 Nanoparticles and Its Application for Photovoltaic Device

CIS (CuInS2) is one of the most effective photovoltaic devices with high stability and efficiency, because of its suitable bandgap (1.5eV). Moreover, it does not contain toxic materials, such as Se, within its components. However, productivity and utilization of natural resources under the gas phase synthesis method is relatively low, since vaporizing temperature of elements is extremely different. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase.Here, we have already developed a synthesizing method of single phase and homogenous CI (CuIn) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly.However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated.To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions.By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents.XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions.In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution.Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles.Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

Water Phase Synthesis Method of CuInS2 Nanoparticles and Its Application of Photovoltaic Device

CIS (CuInS2) is one of the most effective photovoltaic devices with high stability and efficiency, because of its suitable bandgap (1.5eV). Moreover, it does not contain toxic materials, such as Se, within its components. However, productivity and utilization of natural resources under the gas phase synthesis method is relatively low, since vaporizing temperature of elements is extremely different. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase.Here, we have already developed a synthesizing method of single phase and homogenous CI (CuIn) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly.However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated.To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions.By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents.XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions.In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution.Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles.Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

Synthesis of CuInS2 Particles in Aqueous Solution for Printable Photovoltaic Device

CuInS2(CIS) is one of the most effective photovoltaic devices with high stability and efficiency, since the bandgap of CIS is 1.5eV while ideal band gap for solar cell is 1.4eV. Moreover, unlike Cu(In,Ga)Se2(CIGS), it does not contain toxic materials, such as Se. However, since vaporizing temperature of four elements (Cu, In, Ga, Se) is extremely different, productivity under the gas phase is relatively low, which read the large amount of waste of resources. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase. Here, we have already developed a synthesizing method of single phase and homogenous copper-indium(CI) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly. However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated. To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions. By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents. XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions. In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution. Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles. Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

Structural and optical analysis of single phase CuInS2 nanocrystals for solar cell applications

Nanostructured phase pure CuInS2 particles have been successfully synthesized by solid state melt growth method. The crystallographic structure, morphological, chemical composition and optical properties of synthesized sample have been characterized by various analytical techniques, includes X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray (EDAX), UV–vis–NIR diffuse reflectance spectroscopy and photoluminescence spectroscopy. From the XRD spectra chalcopyrite structure of CuInS2 sample with phase pure nano particles is confirmed. Annealing promotes the grain size and crystallinity of the CuInS2 sample and is clearly indicated by XRD analysis. The optical band gap energy of CuInS2 sample is calculated to be 2.61 eV, which has also been confirmed by photoluminescence spectroscopy. SEM micrograph shows that the CuInS2 sample is composed of particles ranges from 25–50 nm in size. Annealed sample confirms the increase of particle size up to 85 nm. Compositional stability of CuInS2 phase pure nano particles have been studied by thermo gravimetric analysis. The effect of annealing temperatures on the structural and morphological properties of CuInS2 nanocrystals synthesized by solid state reactions has also been studied in this report.

Synthesis and characterization of CuInS2 nanocrystalline semiconductor prepared by high-energy milling

Nanocrystalline CuInS2 particles have been synthesized from copper, indium, and sulfur powders by high-energy milling in a planetary mill in an argon atmosphere. Structural characterization of the prepared nanoparticles, including phase identification, Raman spectroscopy, specific surface area measurement, and particle size analysis were performed. The optical properties were studied using UV–Vis absorption and photoluminescence (PL) spectroscopy. The production of CuInS2 (JCPDS 027-0159) particles with a crystallite size of about 17.5–23.5 nm was confirmed by X-ray diffraction. The crystal structure has a tetragonal body-centered symmetry belonging to the I-42d space group. The Raman spectra also proved the formation of pure CuInS2 nanoparticles. TEM and HRTEM measurements revealed the presence of nanoparticles of different dimensions (10–20 nm) and their tendency to form agglomerates. The nanoparticles tend to agglomerate due to their large specific surface area. The average size of the synthesized particles was determined by photon cross-correlation spectroscopy to be in the range of 330–530 nm (bimodal size distribution). The band gap of the CuInS2 particles is 2 eV which is wider than that in bulk materials. The decrease in size leads to the blue-shift of the PL spectra. Therefore, CuInS2 nanoparticles are promising candidates for optical applications, and they have high potential in solar energy conversion.

Fabrication of n-type CuInS2 modified TiO2 nanotube arrays heterostructure photoelectrode with enhanced photoelectrocatalytic properties

A novel n-type CuInS2 modified TiO2 nanotube arrays (NTs) heterostructure photoelectrode was successfully prepared via an ultrasonication-assisted cathodic electrodeposition strategy. CuInS2 particles were uniformly decorated on the inner and external walls of the TiO2 NTs electrode. The stoichiometry measured by XPS and ICP-OES clearly illustrated the excess indium. Mott–Schottky analysis further demonstrated CuInS2 possessed an n-type feature. Optical characterizations indicated that the introduced CuInS2 could extend the visible-light response range and enhance the visible light photoactivity. Moreover, the electrochemical measurements attested to a significant improvement of the interfacial electron-transfer properties. The photoelectrocatalytic (PEC) activity of CuInS2/TiO2 NTs electrode was evaluated by degradation of 2-chlorophenol (2-CP) under visible light irradiation (λ>420nm). The results indicated that the as-prepared CuInS2/TiO2 NTs electrode displayed much higher PEC performance than that of the pure TiO2 NTs electrode.

Structure and morphology evolution in mechanochemical processed CuInS2 powder

CuInS2 powders were synthesized by mechanochemical process from copper, indium and sulfur powders. A self-propagating combustion occurred during the milling process. Phase structure, morphology evolution and component uniformity of Cu–In–S system have been studied by X-ray diffraction, scanning electron microscope and energy dispersive analysis, respectively. Optical property of ball milled CuInS2 has been detected by UV–Vis spectroscopy. The results show that there is no intermetallic phase was observed before the self-propagating combustion though morphology changed obviously during this stage. The detected composition of mixed powder converges toward the original proportion with increased milling as the particle sizes decreased. Homogeneous CuInS2 particles less than 5μm are obtained after milling 120min. The reason of mechanically induced self-propagating reaction occurs during milling in this system is also discussed. The UV–Vis absorption spectrum shows the milled CuInS2 has a broad absorption over the entire visible light and extending into the near-infrared region and its band gap is 1.52eV.

Shape and size controlled synthesis of CuInS2 particles in polyalcohol system used as “printable ink” for thin films

Chalcopyrite semiconductor CuInS2 (CIS) particles are synthesized using a simple method and low-cost solvent. Two kinds of agents are used to adjust and control the sizes and shapes of the particles. The phases, morphologies and grown processes of the products are studied. The results show that the sizes and shapes of the CIS particles can be adjusted and controlled. Furthermore, CIS thin films are fabricated using these two kinds of particles. The thin films appear different morphologies and qualities via different kinds of particles, indicating the importance of controlling the shape and size of the precursor particles.

Investigations of solvents and various sulfur sources influence on the shape-controlled synthesis of CuInS2 nanocrystals

CuInS2 (CIS) nanocrystals were successfully synthesized through a hot-injection technique employing a reaction of copper (I) acetate and indium (III) acetate with tert-dodecanethiol as a source of sulfur, and trioctylphosphine oxide and 1-dodecanethiol were used as ligands. The reaction medium was a mixture of two solvents: oleylamine and 1-octadecene. Varying the ratio between both solvents leads to the formation of wurtzite CuInS2 particles with shapes ranging from triangular to rod-shaped with length up to 50 nm. Oleylamine turned out to influence the reaction condition in two opposite ways: by leading to monomer depletion before the injection of the sulfur precursor, and at the same time increasing the activity of the monomers remaining in solution. By changing the sulfur source from tert-dodecanethiol to sulfur dissolved in oleylamine, triangular particles with zinc blend structure and a smaller size (~5 nm) were synthesized. The final materials were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and absorption spectroscopy (UV–Vis).

Nonlinear optical properties of CuxS and CuInS2 nanoparticles in sol–gel glasses

Silica glasses with ultrafine CuxS and CuInS2 particles (average radius of 5±3 nm) were fabricated by means of a sol–gel technique. Linear and differential absorption spectra were studied. The glasses reveal absorption peaks in the 600–700 nm range associated with the first excitonic resonance in the quantum confined particles. Laser excitation by 540 nm pulses leads to the induced absorption effect in the 480–980 nm spectral range. The relaxation of the induced absorption has a time constant equal to about 500 ps for CuS-doped glasses and a biexponential type (with τ1≈30 ps and τ2>1 ns) for CuInS2-doped ones.