Copper Indium Sulfide Research Articles

Synthesis and characterization of CuInS2 nanostructures and their role in solar cell applications

Copper indium sulphide (CuInS2) is regarded as an active material for solar cells owing to its unique optical properties, non-toxicity, low-cost and easy of synthesis. The cost and performance of the solar cell depend not only on the materials, but also on the preparation and fabrication techniques, which are significant for improving the efficiency of the device. In current study, the co-precipitation method was instigated to synthesize the chalcopyrite CuInS2 semiconductor nanoparticles (NPs) and the effects of annealing temperature on the size, agglomeration, functional groups and elemental compositions were investigated. In the next step, CuInS2 films were deposited on a conductive substrate using a stable dispersion by an electrophoretic deposition technique. Subsequently, the synthesized NPs and films were subjected to structural, morphological, optical and elemental analysis. X ray diffraction (XRD) revealed the formation of the tetragonal chalcopyrite CulnS2 NPs at 200 °C and 300 °C with the most prominent peak along the (112) orientation, and the calculated crystallite size ranged from 11.32 to 32.74 nm. Furthermore, the films were characterized by scanning electron microscopy, which showed the surface modifications of the electrophoretically deposited films at moderate voltage. The photovoltaic analysis shows that the cell fabricated at 90 V increases the cell's efficiency up to 1.27%, while the cells fabricated at 100 and 110 V increase the efficiency to 1.13% and 0.83%, respectively.

Photocatalytic water splitting on the CuInS2 photoelectrodes: Effects of co-electrodeposition mechanisms on the photoelectrochemical properties

Copper indium sulfide (CuInS2, CIS) was fabricated by co-electrodeposition (co-ED) of the Cu-In (CI) alloy on the Mo-electrode, followed by sulfurization in the presence of solid sulfur. The morphology, crystal structures and In/Cu compositions of CIS were found to depend on the preparation conditions of the CI, i.e., the solution concentration, applied potential and amount of Coulomb charge. For the mechanism of CI formation, the copper species were preferentially deposited on the Mo electrode in their initial state, and subsequently the indium species were deposited on the Cu layer by the effects of the concentration gradient at the electrode interface. Furthermore, the optimized CIS possessed a chalcopyrite structure with an In/Cu ratio of 1.0 having a band-gap at ca. 1.5 eV. The Pt-In2S3/CIS photoelectrode was applied for photocatalytic water splitting and it demonstrated high photoelectrochemical (PEC) water splitting to evolve H2 (50 μmol h−1 cm−2) with a Faradic efficiency of 83.4% at + 0.1 V vs. RHE. The co-ED method, thus, enabled the facile fabrication of CI, and the prepared CIS clearly exhibited promising activity as a photo-absorber for PEC water splitting.

Light-harvesting antennae based on copper indium sulfide (CIS) quantum dots.

Copper indium sulfide quantum dots (CIS QDs) and their core-shell analogues (CIS@ZnS QDs) were functionalized with pyrene chromophores via a dihydrolipoamide bifunctional binding moiety: UV excitation of the pyrene chromophores resulted in sensitized emission of the CIS core because of an efficient energy transfer process; the core-shell hybrid system exhibits a 50% increased brightness when excited at 345 nm.

Honeycomb-structured copper indium sulfide thin films obtainedviaa nanosphere colloidal lithography method

Honeycomb structured copper indium sulfide layers are successfully realizedviaa nanosphere lithography route employing polystyrene nanosphere array templates and metal xanthates or a nanocrystal ink.

Pre-deposited alkali (Li, Na, K) chlorides layer for effective doping of CuInSSe thin films as absorber layer in solar cells

We introduce an effective method for copper indium sulfide selenide (CISSe) doping with different alkali metals (Li, Na and K) based on a pre-deposited alkali chloride layer. A simple and fast spray method is used for pre-deposition of alkali chloride layer (LiCl, NaCl, KCl) on substrate surface before spray pyrolysis deposition of copper indium disulfide CuInS2 (CIS) films followed by selenization. The different properties of alkali-doped CISSe films by the alkali chloride pre-deposition (ACPD) method were compared to the post-deposition treatment (PDT) method. Based on FESEM images, a highly compact film with large grains can be obtained for CISSe films doped with K(∼0.72 μm) and Na (∼0.56 μm) by the ACPD method that is considerably higher than un-doped films (∼0.47 μm). While for the PDT method, grain size decreased after the doping process. UV–Vis analysis showed that alkali atoms with larger size result in more band gap widening of CISSe film. According to Mott-Schottky results, all films are p-type but doping density is dependent on the doping method. CISSe films doped by the ACPD method show smaller doping density, the smallest value of carrier concentration is 3.1 × 1017 cm−3 for K-doped CISSe film. All CISSe doped films by ACPD method show higher mobility compared to CISSe film doped by PDT method and larger atom results in higher mobility. The numerical modeling work using SCAPS software showed that solar device with ACPD K-doped CISSe film as absorber layer results in higher efficiency compared to Li, Na- doped and undoped CISSe films.

Tunable structural, morphological and optical properties of undoped, Mn, Ni and Ag-doped CuInS2 thin films prepared by AACVD

The preparation of high-quality copper indium sulphide, CuInS2 photo-absorber material with tunable properties for efficient, low-cost, thin film solar cells using scalable methods remains a challenge. In order to address this, high quality off-stoichiometric undoped and Mn, Ni and Ag-doped CuInS2 (CIS) thin films have been deposited onto glass substrates by aerosol-assisted chemical vapour deposition (AACVD) using metal diethyldithiocarbamate precursors at temperatures of 350, 400 and 450 °C. Data from powder X-ray diffraction (p-XRD), Raman spectroscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) suggest a correlation of morphology and composition of tetragonal phase (chalcopyrite and copper-gold-type) sulphur-deficient microcrystalline CIS thin films. For undoped thin films, near-infrared optical absorption and emission with tunable band gap between 1.32 and 1.42 eV are likely associated with donor-acceptor pairs involving deep or shallow electronic states such as sulphur vacancies (VS••), indium-copper anti-sites (InCu••) and indium interstitials (Ini•••) as donors and copper vacancies (VCu′) as acceptors. Whilst Mn-doped thin films exhibit minimal tunable properties, Ni and Ag-doped films exhibit tunable morphology, composition and near-infrared absorption for small dopant content. Though further studies are required to explore the defect chemistry, these results show the utility of AACVD in tuning structural, morphological and optical properties of undoped, Mn, Ni and Ag-doped CIS thin films.

Unraveling the Emission Pathways in Copper Indium Sulfide Quantum Dots.

Semiconductor copper indium sulfide quantum dots are emerging as promising alternatives to cadmium- and lead-based chalcogenides in solar cells, luminescent solar concentrators, and deep-tissue bioimaging due to their inherently lower toxicity and outstanding photoluminescence properties. However, the nature of their emission pathways remains a subject of debate. Using low-temperature single quantum dot spectroscopy on core-shell copper indium sulfide nanocrystals, we observe two subpopulations of particles with distinct spectral features. The first class shows sharp resolution-limited emission lines that are attributed to zero-phonon recombination lines of a long-lived band-edge exciton. Such emission results from the perfect passivation of the copper indium sulfide core by the zinc sulfide shell and points to an inversion in the band-edge hole levels. The second class exhibits ultrabroad spectra regardless of the temperature, which is a signature of the extrinsic self-trapping of the hole assisted by defects in imperfectly passivated quantum dots.

In situ phase transformation of polytypic zinc-blende/wurtzite copper indium sulfide via a facile polyol method to boost visible-light photocatalytic performance

A zinc-blende/wurtzite (ZB/WZ) copper indium sulfide (CuInS2/CIS) polymorph with high visible-light absorption ability and high charge separation rate was developed by using a facile polyol method. Results showed that when thioacetamide served as a sulfur precursor, the crystalline phase of CIS was zinc-blende. Meanwhile, when thiourea served as a sulfur precursor, the crystalline phase of CIS was wurtzite, which exhibited good photocatalytic acid red 1 (AR1) dye decolorization efficiency. When the precursor/ethylene glycol ratio was 1/50–7/50, the AR1 decolorization efficiency followed the order: T-5-CIS > T-7-CIS > T-3-CIS > T-1-CIS, and the TOC removal efficiency of T-5-CIS was 45.7%. The PL and EIS analyses indicated that T-5-CIS showed the highest charge separation rate. Mott–Schottky analysis demonstrated that the remarkably enhanced photocatalytic decolorization rate was ascribed to the stronger reduction potential of CIS with the mixed ZB/WZ phases and the redox potential difference between the ZB and WZ phases, leading to a good oxidation ability and charge separation. The results indicated that O2− was the main reactive specie in this study, and this study provided a potential photocatalyst in the treatment of dye wastewater.

One-step synthesis of CuInS2 nanoparticles using aqueous chelated metal complexes as a starting material

Thin film compound semiconductor solar cells, including copper indium sulfide (CIS), have potential as next-generation power supply sources. However, recent fabrication processes include gas phase reactions, which consume much energy and generate abundant loss of material resources. Therefore, the development of alternative eco-friendly methods without a gas phase reaction has been actively researched. Herein, we synthesize CIS nanoparticles via a liquid phase reaction using iminodiacetic acid (IDA) and glycine (Gly) as the complex reagent to homogenize copper and indium complexes. The X-ray diffraction (XRD) profiles of the as-synthesized nanoparticles in a buffer solution exhibit broad peaks, which nearly correspond to CIS. These peaks grow sharply after annealing. Selected area electron diffraction and high-resolution transmission electron microscopies indicate the presence of the (112) phase of CIS but the crystallinity of our CIS with IDA and Gly differs. The results indicate that maintaining a homogenized condition of metal complexes by pH stabilization using a buffer solution might be maybe important for aqueous synthesis of CIS.

Analysis of the indium insertions in non-stoichiometric copper sulfide roxbyte, and their effect on the localized surface plasmon resonance of the nanocrystals

After operating what is thought to be an incomplete catalyst-assisted growth of copper indium sulfides, we obtain roxbyite (indium hole-filled non-stoichiometric copper sulfide, Cu $$_7$$ S $$_4$$ , Cu $$_x$$ S, x = $$1.75 -1.78$$ ) with a higher Cu:S ratio in view of its carrier density. This apparent increase of Cu:S ratio and decrease of carrier density is due to the “counterdoping” of the non-stoichiometric copper sulfides by indium atoms. Here, we propose a relatively easy way to synthesize copper sulfides quantum dots with low carrier densities. We rely on the well-known indium as way to decrease the carrier density of the copper sulfide Cu $$_7$$ S $$_4$$ , making the semiconductor suitable for multiple applications (reducing the indium and easily preventing the secondary phase formation). Moreover, we provide an original and practical way to estimate the carrier density of our particles using their localized plasmon resonance. In this paper, we conduct comparative quantitative analyses of the localized surface plasmon resonance (LSPR) of “counterdoped” roxbyite and doped roxbyite synthesized in similar conditions to gauge the effectiveness of the “counterdoping.” Finally, we hope to propose a picture of and focus on a phenomenon that is overlooked in the growth of copper indium sulfide and to offer a pathway for the proposed doping (“counterdoping”) of the copper sulfides.

Solution-Processed All-inorganic Planar Heterojunction Solar Cells by Employing In Situ Grown Interfacial Layer with Dual Functions: Complementary Absorption and Selective Extraction of Photogenerated Holes.

Photovoltaic conversion of renewable solar energy into electricity for sustainable energy production requires efficient, stable, and low-cost solar cells. Developing solution-processed all-inorganic solar cells is a practical scenario in virtue of the high charge mobility and good stability of inorganic semiconductors. Here, for the first time, we present a solution-processed all-inorganic planar heterojunction solar cell based on the nanoparticle film of copper indium sulfide (CuInS2) by using an antimony trisulfide (Sb2S3) nanoparticle film as an interfacial layer between the CuInS2 photon-harvesting layer and cathode. All of the component layers in the solar cell are in a superstrate architecture and sequentially in situ grown on a transparent conducting glass acting as anode by solution-processing methods. The dependences of device performance on the thickness of Sb2S3 film and the reduction of hole-trapping centers in the Sb2S3 film by thioacetamide treatment are investigated. The optimized all-inorganic device exhibits the best power conversion efficiency of 4.85% under AM 1.5G illumination and an excellent thermal stability. It is found that the Sb2S3 interfacial layer sandwiched between the CuInS2 photon-harvesting layer and counter-electrode has dual functions, that is, to provide complementary absorption after CuInS2 attenuation and to act as an effective hole-transporting layer to selectively extract photogenerated holes for effective charge collection efficiency.

Solution-processed fabrication of copper indium sulfide (CuInS2) as optical absorber for superstrate CuInS2/CdS/TiO2 solid-state solar cells

Solution-processed fabrication of copper indium sulfide (CuInS2) as optical absorber for superstrate CuInS2/CdS/TiO2 solid-state solar cells

Luminescent copper indium sulfide (CIS) quantum dots for bioimaging applications.

Copper indium sulfide (CIS) quantum dots are ideal for bioimaging applications, by being characterized by high molar absorption coefficients throughout the entire visible spectrum, high photoluminescence quantum yield, high tolerance to the presence of lattice defects, emission tunability from the red to the near-infrared spectral region by changing their dimensions and composition, and long lifetimes (hundreds of nanoseconds) enabling time-gated detection to increase signal-to-noise ratio. The present review collects: (i) the most common procedures used to synthesize stable CIS QDs and the possible strategies to enhance their colloidal stability in aqueous environment, a property needed for bioimaging applications; (ii) their photophysical properties and parameters that affect the energy and brightness of their photoluminescence; (iii) toxicity and bioimaging applications of CIS QDs, including tumor targeting, time-gated detection and multimodal imaging, as well as theranostics. Future perspectives are analyzed in view of advantages and potential limitations of CIS QDs compared to most traditional QDs.

Enhanced Performance of Quantum Dots Sensitized Solar Cell Utilizing Copper Indium Sulfide and Reduced-Graphene Oxide with the Presence of Silver Sulfide

In this study, rGO/CuInS2 has been successfully prepared onto TiO2 thin film using solvothermal method followed by Ag2S deposition layer by successive ionic layer adsorption and reaction deposition (SILAR) technique. The morphology, structural, and optical properties of TiO2/rGO/CuInS2 thin film were investigated by using field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM), X-ray diffraction (XRD) and ultra-violet-visible near infrared spectrophotometer (UV-Vis). For electrical properties, electrochemical impedance spectra (EIS) and current-voltage (I-V) test investigated the interfacial charge-transfer resistances and the conversion efficiency of the samples. Results showed that the average particles size of the samples ranged from ±46.52 to ±53.97 nm in diameter. UV-VIS analysis indicated that TiO2/rGO/CuInS2 thin film showed better light absorption capability with the presence of Ag2S deposition layers. The rGO/CuInS2 quantum dot sensitized with Ag2S layers exhibit a photovoltaic power conversion efficiency of 0.33%, which has great improvement of short circuit current (ISC) comparing with that of rGO/CuInS2 quantum dot sensitized without Ag2S deposition layers.

Revealing Exciton and Metal–Ligand Conduction Band Charge Transfer Absorption Spectra in Cu-Zn-In-S Nanocrystals

Copper indium sulfide quantum dots (QDs) have attracted substantial attention in recent years due to environmental issues and diverse applications. We report the synthesis and characterization of c...

Fabrication of highly efficient pure blue-emitting electroluminescent devices using ZnSe/ZnSexS1-x/ZnS QDs

Since electroluminescent (EL) quantum dots (QDs) are considered a key component of the next-generation display, and large-scale production of environment-friendly QDs is required for their wide use in commercial displays. Therefore, several studies on non-cadmium QDs, such as indium phosphide (InP) QDs in the III-V category, graphene QDs, and copper indium sulfide (CuInS2) or silver indium sulfide (AgInS2) QDs in the I-III-VI2 category, have been conducted owing to their non-toxicity and good optical properties. Subsequently, significant results have been reported for green and red colors. However, for synthesis of blue QDs, pure blue emission in the range of 440-460 nm has been achieved with few materials. Among them, zinc selenide (ZnSe) is a promising candidate for synthesizing blue QDs. However, owing to the wide band gap (2.7 eV) of ZnSe, highly effective QDs were attained in the violet region (420-440 nm). Here, for the first time, we have synthesized ZnSe/ZnSexS1-x/ZnS QDs emitting at a wavelength of 444 nm with high photoluminescence quantum yield (PLQY) of 77.2%. Also, full width at half maximum (FWHM) of 23.3 nm ensured its excellent color purity. Use of a gradient intermediate shell of ZnSeS in the original ZnSe/ZnS QDs was the key factor behind this achievement. The intermediate gradient shell of ZnSeS around the core delocalizes the electrons, weakening the quantum confinement effect (QCE), hence rendering the emission color of the QDs tunable from violet to blue by manipulating the ratio of selenium (Se) and sulfur (S) in the composites. A blue emission peak centered at 452 nm was observed for the quantum dot light-emitting diodes (QD-LEDs) fabricated using the above-mentioned QDs, and an external quantum efficiency (EQE) of 5.32%, current efficiency of 1.51 cd/A, and power efficiency of 0.74 lm/W were reported. Furthermore, our fabricated device exhibited a maximum brightness of 3,754 cd/m2 and a half operational time (LT50) with 100 cd/m2 initial luminance of 1.27 h, which are the highest values of these parameters to be reported till date for a blue QD-LED fabricated using ZnSe core based QDs in pure blue region.

Synthesis of CuInS2 and CuInS2@ZnX (X = S, Se) nanoparticles for bioimaging of cancer cells using electrochemically generated S2- and Se2-

An electrochemical approach has been used for the aqueous synthesis of low-toxicity and eco-friendly copper indium sulfide (CuInS2) nanocrystals, and related core@shell systems (CuInS2@ZnX, where X = S2- and Se2-). The chalcogenide precursors (S2-, Se2-) were generated in electrochemical cavity cell, using a constant current electrolysis (i = 30 mA and Q = 11.5C), in the presence of metallic precursors (In3+, Cu+, Zn2+), room temperature and argon atmosphere. Firstly, In2S3 seeds were obtained in the intermediate compartment of the cell and converted to CuInS2 by thermoactivated diffusion (colloidal solution under reflux) of Cu+ ions into the In2S3 lattice. Cu+/In3+ ratios = 0.25 and 0.125 were tested for the production of CuInS2 stabilized by l-glutathione (GSH), and characterized by UV–vis and emission spectroscopy, XRD, HRTEM and zeta potential. CuInS2@ZnX nanoparticles were prepared by using the same electrochemical system, paired electrolysis and Zn sacrificial anode. Nanocrystals prepared under Cu+/In3+ = 0.125 reached 3.1% (CuInS2), 4.6% (CuInS2@ZnSe), and 9.6% (CuInS2@ZnS) quantum yields. The CuInS2@ZnX systems presented high cell viability (85%–94%) and internalization in cytosol region of HeLa cells, showing high potential for biological labeling.

Noble Metal Modification of CdS-Covered CuInS2 Electrodes for Improved Photoelectrochemical Activity and Stability

In this paper, efficient and stable photoelectrochemical (PEC) hydrogen (H2) evolution using copper indium sulfide (CuInS2) thin film electrodes was studied. Modification with a cadmium sulfide (CdS) layer led to improved charge separation at the interface between CuInS2 and CdS; however, the photocorrosive nature of CdS induced poor stability of the photocathode. Further surface coating with an electrodeposited Pt layer over the CdS-covered CuInS2 photocathode prevented the CdS layer from making contact with the electrolyte solution, and enabled efficient PEC H2 evolution without appreciable degradation. This indicates that the Pt layer functioned not only as a reaction site for H2 evolution, but also as a protection layer. In addition, it was found that surface protection using a noble metal layer was also effective for stable PEC carbon dioxide (CO2) reduction when appropriate noble metal cocatalysts were selected. When Au or Ag was used, carbon monoxide was obtained as a product of PEC CO2 reduction.

A highly sensitive chemiluminescence assay for diniconazole by using CuInS2 quantum dots

We demonstrate here the first use of water-soluble copper indium sulfide quantum dots (CuInS2 QDs) as the chemiluminescence (CL) reagent and its application to the highly sensitive detection of diniconazole. We utilized a hydrothermal method for synthesis of mercaptopropionic acid-capped CuInS2 QDs, which were characterized by TEM image, EDS, and XRD pattern. The performance of these QDs as the CL reagent was investigated by using several oxidizing agents and found that acidic potassium permanganate (KMnO4) gave the highest CL signal. CuInS2 QDs/KMnO4 as a novel CL probe was then used for assay of diniconazole based on its unique enhancing effect. In the optimum settings, a linear calibration plot was obtained for diniconazole in the concentration range of 4.0 × 10−9 mol L−1–1.5 × 10−6 mol L−1, with a limit of detection of 1.0 × 10−9 mol L−1. The study of interferences and recoveries confirmed the suitability of the method for assay of environmental water samples.

Hydrothermal Synthesis of Aqueous-Soluble Copper Indium Sulfide Nanocrystals and Their Use in Quantum Dot Sensitized Solar Cells.

A facile hydrothermal method to synthesize water-soluble copper indium sulfide (CIS) nanocrystals (NCs) at 150 °C is presented. The obtained samples exhibited three distinct photoluminescence peaks in the red, green and blue spectral regions, corresponding to three size fractions, which could be separated by means of size-selective precipitation. While the red and green emitting fractions consist of 4.5 and 2.5 nm CIS NCs, the blue fraction was identified as in situ formed carbon nanodots showing excitation wavelength dependent emission. When used as light absorbers in quantum dot sensitized solar cells, the individual green and red fractions yielded power conversion efficiencies of 2.9% and 2.6%, respectively. With the unfractionated samples, the efficiency values approaching 5% were obtained. This improvement was mainly due to a significantly enhanced photocurrent arising from complementary panchromatic absorption.