In2S3 Layers Research Articles

Comparative study of interfacial charge transfer at the junction between CuInS2:In2S3/g-C3N4 photocatalysts for sacrificial hydrogen evolution activity

The quest for sustainable and efficient renewable energy sources has escalated in recent years, with photocatalytic hydrogen production gaining prominence due to its potential to harness solar energy for clean fuel generation. In this study, we design 2D/2D heterostructure CuInS2:In2S3/g-C3N4 nanosheets utilizing electrostatic interaction for hydrogen evolution reaction under visible light irradiation. Integrating CuInS2:In2S3 and g-C3N4 layers to form an interfacial 2D:2D heterostructure results in a broad light absorption range, effective charge separation, and excellent stability. The heterostructure ensures efficient interfacial charge transfer pathways, mitigating electron-hole recombination and promoting hydrogen evolution. The hybrid nanosheets prepared with the hydrothermal method exhibited ∼40-fold synergistic enhancement in hydrogen production and long-term stability. The synergistic boost in activity resulted from the formation of S-scheme heterojunctions (CuInS2/g-C3N4 and CuInS2/In2S3) within hybrid nanosheets.

A Thin In2 S3 Interfacial Layer for Reducing Defects and Roughness of Cu2 ZnSn(S,Se)4 Thin-Film Solar Cells.

Cu2 ZnSn(S,Se)4 (CZTSSe) has generated considerable research interest owing to its composition of abundant elements and excellent light-absorption properties. However, CZTSSe thin-film solar cells suffer from a considerable deficit in the open-circuit voltage (VOC ), which is mainly due to the severe interfacial recombination induced by the rough surface of CZTSSe and numerous physical defects. In this study, to improve the morphology and reduce the interfacial recombination, an In2 S3 passivation layer was introduced between the CZTSSe and CdS layers via a chemical bath deposition process, and the effects of the In2 S3 layer on the device performance were systematically examined by performing various electrodynamic analyses. The CZTSSe solar cells with thin In2 S3 layers exhibited impressive increases in VOC and conversion efficiency (from 7.33 to 9.24 %), due to the suppression of physical defects and the refined surface morphology resulting from filling the voids and pinholes. In addition, the nanoscale roughness of the In2 S3 /CZTSSe surface increased the number of nucleation sites for the CdS nuclei, which may reduce the activation energy of the heterogeneous nucleation. The presence of In2 S3 layer resulted in uniform growth of CdS without macroscopic CdS agglomerates (i. e., reduced roughness of full devices), which improved the quality of the interface. These findings confirmed that the reduction of physical defects and the improved deposition of the CdS layer enabled by the added In2 S3 passivation layer improved the device performance.

Synthesis of Cu(In,Ga)S2 nanoparticles via hot-injection method and incorporation with 3D-ZnO/In2S3 heterojunction photoanode for enhanced optical and photoelectrochemical properties

Copper-based ternary Cu(In,Ga)S2 (CIGS) nanoparticles (Np) in chalcopyrite crystal phase have been synthesized via hot-injection method to be used as colloidal Np ink for 3D-ZnO nanosheet thin film sensitization for the enhancement of light absorption in the visible region due to its suitable bandgap. Additionally, an indium sulfide (In2S3) layer has been deposited on the 3D-ZnO/CIGS thin-film for surface modification of CIGS layer to protect against photocorrosion, and bare 3D-ZnO for constructing suitable band alignment in photoelectrochemical water splitting (PEC) applications for hydrogen production. The 3D-ZnO/In2S3 photoelectrode generated the photocurrent density (J) of ~ 1.1 mA.cm−2 (at 1.2 V vs. RHE) and an incident photon to-current efficiency (IPCE) of 35.0% at 382 nm. On the other hand, after incorporation of CIGS-Np between 3D-ZnO NS and In2S3 layers, 2.2 mA.cm−2 of J (at 1.2 V vs. RHE) and 53.2% IPCE at 382 nm have been observed.

Electrical and optical characterization of sprayed In2S3 thin films as an electron transporting layer in high efficient perovskite solar cells

This study represents the investigation of In2S3 thin films, which have been deposited with different Indium salts (Chloride, Acetate, and Nitrate) using the Chemical Spray Pyrolysis (CSP) method. The Mott-Schottky analysis has been used in case of studying the electrical properties of films such as conduction and valence band, carrier densities, Fermi level (Efn), flat band potential, and semiconductor type. In the next step, the Rb1MAFA perovskite solar cell has been simulated, and the results have been validated by the experimental data (with the least parameters for fitting). Finally, In2S3 layers have been inserted on the SnO2 layer to decrease the recombination rate and enhance the efficiency of the solar cell. The results represent that the In2S3 layers with acetate source improve the band bending at the perovskite/ETL interface, the electron transfer will increase, and the result would be an increment in the open-circuit voltage (VOC), as well as the cell PCE. The efficiency of 23.47% is the recorded PCE, which is approximately 3% more than the reference case.

Growth of In2S3 nanolayers on F-Mica, SiO2, ZnO, and TiO2 substrates using chemical vapor deposition

In this study, 2D layers of β-In2S3 have been synthesized on different substrates such as SiO2, F-Mica, ZnO, and TiO2 using the chemical vapor deposition (CVD) technique. Different morphologies of In2S3 2D nanoflakes have been obtained within the temperature range of 550–850 °C. These nanolayers have been characterized by using FESEM, XRD, and Raman spectroscopy techniques. The results show well-formed nanodomains of β-In2S3 with a tetragonal phase on different substrates by CVD technique at an optimized temperature of 750 °C, although the morphology of the grown layer depending sensitively upon the substrates. The initial results show ohmic current-voltage characteristics, the fast photoconductive response of In2S3 layers. In2S3 grown on ZnO substrates as a base layer show enhanced photoelectrochemical properties because of increased visible light absorption, as indicated by optical absorption results.

Impact of thermal annealing inducing oxidation process on the crystalline powder of In2S3

Inorganic two-dimensional semiconductor indium sulfide (In2S3) has recently attracted considerable attention as a buffer material in the field of thin-film photovoltaics, photo electrochemical cells and other energy-related applications. Compared with this growing interest, however, detailed characterizations of the commercial material are not done. The present investigation deals with the systematic investigation of the physical properties of powdered β-indium sulfide (In2S3). The crystalline structure, the composition, and the morphological properties of the samples were characterized using a range of techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). X-ray diffraction patterns revealed mixed peaks of In2S3 and In2O3 for the sample annealed at 400 °C. The In2O3 peaks were crystalline with a cubic phase with a (222) preferential orientation. These results were supported by the FTIR, and XPS studies. Thus, a significant correlation was established between the annealing temperature and the TEM images. The main conclusion of the paper opens the possibility of using In2S3 layers for solar cells.

Influence of Substrate Temperature during InxSy Sputtering on Cu(In,Ga)Se2/Buffer Interface Properties and Solar Cell Performance

Indium sulfide (InxSy)—besides CdS and Zn(O,S)—is already used as a buffer layer in chalcopyrite-type thin-film solar cells and modules. We discuss the influence of the substrate temperature during very fast magnetron sputtering of InxSy buffer layers on the interface formation and the performance of Cu(In,Ga)Se2 solar cells. The substrate temperature was increased from room temperature up to 240 °C, and the highest power conversion efficiencies were obtained at a temperature plateau around 200 °C, with the best values around 15.3%. Industrially relevant in-line co-evaporated polycrystalline Cu(In,Ga)Se2 absorber layers were used, which yield solar cell efficiencies of up to 17.1% in combination with a solution-grown CdS buffer. The chemical composition of the InxSy buffer as well as of the Cu(In,Ga)Se2/InxSy interface was analyzed by time-of-flight secondary ion mass spectrometry. Changes from homogenous and stoichiometric In2S3 layers deposited at RT to inhomogenous and more sulfur-rich and indium-deficient compositions for higher temperatures were observed. This finding is accompanied with a pronounced copper depletion at the Cu(In,Ga)Se2 absorber surface, and a sodium accumulation in the InxSy buffer and at the absorber/buffer interface. These last two features seem to be the origin for achieving the highest conversion efficiencies at substrate temperatures around 200 °C.

Annealing and plasma treatment effect on structural, morphological and topographical properties of evaporated β-In2S3 films

Indium sulfide (In2S3) is a wide bandgap semiconductor, which is widely used as a window/buffer layer in thin film solar cell applications. In2S3 thin films were deposited using thermal evaporation technique and were annealed in sulfur ambient at 200 °C and 250 °C. Further, these films were treated in inductively coupled argon plasma sputtering with an average argon ion energy of 75 eV for 30 s. The paper presents the effect of Ar-plasma treatment on structure, elemental composition, morphology and topography of In2S3 films and the results were reported. Further, the optimized In2S3 layers were continued for plasma etching process with an average argon ion energy of 25 eV to study the effect of plasma etching duration on the growth of metallic indium nanoparticles over the film surface and the results were discussed in detail.

Sputtered Inx(O,S)y Buffer Layers for Cu(In,Ga)Se2 Thin-Film Solar Cells: Engineering of Band Alignment and Interface Properties.

We propose a simple approach to engineering the sputtered Inx(O,S)y/Cu(In,Ga)Se2 heterojunction, in terms of band alignment and interface properties. The band alignment was tailored by tuning the base pressure of the sputtering deposition to incorporate oxygen into deposited In2S3 layers (termed as Inx(O,S)y). The interface properties were improved by optimizing the air-annealing temperature on Inx(O,S)y/Cu(In,Ga)Se2 stacked layers. Increasing the base pressure raises the O/(S + O) ratio contained in deposited Inx(O,S)y films and thus widens the band gaps. This could effectively tailor the conduction band offset (ΔEC) at the Inx(O,S)y/Cu(In,Ga)Se2 interface from a cliff (-0.25 eV) to a nearly flat band (0.07 eV) alignment. On the other hand, the extra air annealing at 235 °C did not significantly change the band alignment but did ameliorate the interface properties by reducing the Cu content at the Cu(In,Ga)Se2 surface and diminish the interface defect density induced by sputtering damages. The former might enhance the type of inversion and increase the hole barrier at the interface, preventing the detrimental recombination behavior. The latter could effectively strengthen the junction quality. Consequently, our approach substantially enhances the cell efficiency from 2.30% to 11.04%.

Inexpensive methodology to prepare TiO2/CuInS2 hetero-junctions for photovoltaic applications

TiO2 and CuInS2 (CIS) hetero-junctions were prepared using low-cost, solution-based techniques. Using conducting glass (FTO) as substrate, a thin film of TiO2 and an ultrathin film of In2S3 that acts as buffer layer were deposited by spray pyrolysis. CIS was electrodeposited on top of this duplex layer, at pH 8, room temperature and at constant potential.A solar cell consisting of FTO/TiO2/In2S3/CIS/graphite was built in superstrate configuration. Morphology, thickness, crystalline structure and chemical composition were analyzed by electronic microscopy, x-ray diffraction and Raman spectroscopy. CuInS2 films were found to be crystalline with a thickness of 0.4 µm and showed good adhesion. Current–voltage curves in the dark and under illumination proved that the solution-based and vacuum-free deposition of these materials has promising photovoltaic applications. Different thicknesses of the buffer layer were evaluated and the best results were found for In2S3 layers deposited with 6 spray cycles. The best solar cell performance showed an efficiency equal to 3.3% with a Voc = 0.583 V, Jsc = 17.7 mA cm−2, FF = 0.32.

Effect of film thickness on physical properties of RF sputtered In2S3 layers

Indium sulfide (In2S3) layers were deposited by RF magnetron sputtering process with different thickness. The effect of thickness on structural, morphological, optical and photo-conductive properties of the In2S3 layers has been studied. In2S3 layers exhibit near stoichiometric chemical composition and single tetragonal phase with (103) preferred orientation. Variation of surface morphology, Raman bands and optical transmittance of the films have been observed with the increase of film thickness. Energy band gap of the layers determined from transmittance spectra were 2.44–2.66eV (direct) and 1.82–2.06eV (indirect), respectively. Based on the measured optical constants (n and k), the Wemple–DiDomenico model was performed to determine values of single oscillator energy (Eo), dispersion energy (Ed), optical band gap (Eg) and high frequency dielectric constant (ε∞). The determined β parameter indicates In2S3 as an ionic compound. The ε∞ values agree well with that of calculated according to the Spitzer–Fan model. Photoconductivity properties of the films were analyzed relating to the rate competition among photo-generation, recombination and trapping of carriers.

Role of Cl on Diffusion of Cu in In2S3 Layers Prepared by Ion Layer Gas Reaction Method

Ion layer gas reaction (ILGAR) method allows for deposition of Cl-containing and Cl-free In2S3 layers from InCl3 and In(OCCH3CHOCCH3)3 precursor salts, respectively. A comparative study was performed to investigate the role of Cl on the diffusion of Cu from CuSCN source layer into ILGAR deposited In2S3 layers. The Cl concentration was varied between 7 and 14 at.% by varying deposition parameters. The activation energies and exponential pre-factors for Cu diffusion in Cl-containing samples were between 0.70 to 0.78 eV and between 6.0 × 10−6 and 3.2 × 10−5 cm2/s. The activation energy in Cl-free ILGAR In2S3 layers was about three times less compared to the Cl-containing In2S3, and the pre-exponential constant six orders of magnitude lower. These values were comparable to those obtained from thermally evaporated In2S3 layers. The residual Cl-occupies S sites in the In2S3 structure leading to non-stoichiometry and hence different diffusion mechanism for Cu compared to stoichiometric Cl-free layers.

Deposition of ultra thin CuInS2 absorber layers by ALD for thin film solar cells at low temperature (down to 150 °C)

Two new processes for the atomic layer deposition of copper indium sulfide (CuInS2) based on the use of two different sets of precursors are reported. Metal chloride precursors (CuCl, InCl3) in combination with H2S imply relatively high deposition temperature (Tdep = 380 °C), and due to exchange reactions, CuInS2 stoechiometry was only achieved by depositing In2S3 layers on a CuxS film. However, the use of acac- metal precursors (Cu(acac)2, In(acac)3) allows the direct deposition of CuInS2 at temperature as low as 150 °C, involving in situ copper-reduction, exchange reaction and diffusion processes. The morphology, crystallographic structure, chemical composition and optical band gap of thin films were investigated using scanning electronic microscope, x-ray diffraction under grazing incidence conditions, x-ray fluorescence, energy dispersive spectrometry, secondary ion mass spectrometry, x-ray photoelectron spectroscopy and UV–vis spectroscopy. Films were implemented as ultra-thin absorbers in a typical CIS-solar cell architecture and allowed conversion efficiencies up to 2.8%.

Meyer-Neldel rule for Cu (I) diffusion in In2S3 layers

The nature of barriers for atomic transport in In2S3 layers has been varied by addition of chlorine. Diffusion of Cu(I) from a removable CuSCN source was used to probe the variation of the barriers. The Meyer-Neldel (compensation) rule was observed with a Meyer-Neldel energy (EMN) and a proportionality prefactor (D00) amounting to 40 meV and 5 × 10−14 cm2/s, respectively. D00 shows that the elementary excitation step is independent of the specific mechanism and nature of the barrier including different densities of Cl in In2S3. The value of EMN implies that coupling of the diffusing species to an optical-phonon bath is the source of the multiple excitations supplying the energy to overcome the diffusion barriers.

Surface photovoltage spectroscopy on Cu(In,Ga)(S,Se)2/ZnS‐nanodot/In2S3 systems

ABSTRACTSingle layers and combined layer systems with Cu(In,Ga)(S,Se)2, ZnS‐nanodot (nd) and In2S3 layers were investigated by surface photovoltage spectroscopy in the Kelvin‐probe arrangement and compared with the open‐circuit voltage (VOC) of solar cells. The In2S3 and ZnS‐nd layers were prepared by the spray ion layer gas reaction (ILGAR) technique from Indium chloride (InCl3), Indium acetylacetonate (In(acac)3) and Zinc acetylacetonate, respectively. The surface photovoltage signals of Cu(In,Ga)(S,Se)2 were larger for the Cu(In,Ga)(S,Se)2/ZnS‐nd/In2S3 than for the Cu(In,Ga)(S,Se)2/In2S3 layer system showing that a ZnS‐nd layer additionally passivated the Cu(In,Ga)(S,Se)2 surface. ILGAR In2S3 deposition from InCl3 precursor solution led to a modification of surface defects of ZnS‐nd and to generation of defect states below the band gap of Cu(In,Ga)(S,Se)2, which has not been observed for deposition from Indium acetylacetonate precursor. Defect generation during ILGAR In2S3 deposition with InCl3 precursor resulted in a lower VOC of Cu(In,Ga)(S,Se)2/ZnS‐nd/In2S3/ZnO : Al solar cells. Copyright © 2012 John Wiley & Sons, Ltd.

Atomic layer deposition of zinc indium sulfide films: Mechanistic studies and evidence of surface exchange reactions and diffusion processes

The authors present the elaboration of zinc indium sulfide (ZnInxSy) thin films in the context of a cadmium-free buffer layer development for copper indium gallium diselenide photovoltaic solar cells. The films were deposited by atomic layer deposition (ALD) from ZnEt2 (DEZ), In(acac)3 (acac = acetylacetonate), and H2S at 200 °C. In situ growth kinetics studies were performed with the quartz crystal microbalance technique to determine the respective mass gain per cycle of ZnS and In2S3 layers, allowing determination of the atomic compositions of the ZnInxSy thin films to be expected if the deposition strictly follows the rule of mixtures. As the experimental atomic compositions of the ZnInxSy films differ significantly from this rule, a comprehensive study of the growth mechanism was performed to determine the nature of the side reactions. First, an exchange reaction between In2S3 and the Zn precursor was identified, though this process is not sufficient to account for the experimental data, and therefore, a second process which corresponds to the diffusion of species within the film was also found to take place. Ultimately, the atomic compositions of the ZnInxSy films can be explained by a rate-limited exchange reaction at the surface between DEZ and the In2S3 layer, combined with diffusion of the species in the whole film. More generally, such side reactions should be considered in ALD of multinary compounds, even at low temperature.

Copper diffusion in thin In2S3 layers investigated by Rutherford Backscattering Spectroscopy

Copper diffusion in thin In2S3 layers was investigated by measuring copper concentration profiles with Rutherford Backscattering Spectroscopy (RBS). For this purpose In2S3 layers (thickness 100nm) were evaporated on crystalline silicon substrates and Cu was diffused from a CuSCN surface layer at temperatures between 150 and 250°C. The CuSCN source layer was removed in pyridine solution before RBS measurements were performed. Diffusion coefficients of Cu in In2S3 were obtained by simulating the diffusion process in a one-dimensional model and comparing measured and simulated Cu concentration profiles. The values of the exponential prefactor of the diffusion coefficient and of the activation energy were 9×10−11cm2/s and 0.3eV, respectively.

Formation of a disorderd hetero‐junction by diffusion of CuI from CuSCN into In2S3 layers: A surface photovoltage study

AbstractCharge‐selective disordered hetero‐junctions were formed in evaporated In2S3 layers by diffusing at 200 °C CuI from a CuSCN source. The thicknesses of In2S3 layers and diffusion times were varied between 5 and 80 nm and between 2 and 19 min, respectively. In some cases CuSCN layers were etched back with pyridine. Spectral and time‐dependent surface photovoltage measurements were carried out in the capacitor arrangement. It was observed that a competing process of charge separation and relaxation was initiated together with the formation of the charge‐selective In2S3/In2S3:Cu hetero‐junction.Modulated SPV amplitude for different annealing times and thicknesses of the evaporated In2S3 layers. magnified image

Chemical characterisation of evaporated In2Sx buffer layers in Cu(In,Ga)Se2 thin‐film solar cells with SNMS and SIMS

AbstractFor the series production of Cu(In,Ga)Se2 (CIGS)‐based thin‐film solar cells it is desirable to replace the thin CdS buffer layer between absorber and transparent front contact by non‐toxic, low‐absorbing semiconductors. In2S3, deposited by atomic layer deposition, has already been qualified as an alternative buffer material. In this work, results of indium sulphide buffer layers deposited by thermal evaporation are presented. Pressed powders with different compositions and morphology were used for evaporation at about 720 °C, resulting in different layer compositions and cell performances. The composition of the initial powder material and of the pellets after the deposition steps was determined by XRF. The deposited In2SxOy buffer layers and the buffer/absorber interface region were analysed by SIMS and sputtered neutral mass spectrometry (SNMS) depth profiling.Fine‐grained pressed In2S3 powder evaporates rather homogeneously during the entire deposition run, resulting in nearly stoichiometric In2S3 layers. S and Cl are evaporated preferentially from pellets of coarse‐grained, S‐poor In2S2.4 powder containing 2 at% Cl, leading to excess S and high Cl concentrations in the first deposited layer. The subsequent layers are S‐poor and the In/S ratios continue to increase. In all interface regions additional amounts of Se, In, and Ga are detected, which could be attributed to the Cu‐poor defect layer on top of the CIGS absorbers. The best solar cell performance with efficiences of about 13% was achieved with the S‐rich buffer layers. Stoichiometric In2S3 or S‐poor layers yield lower efficiences between 8 and 11%. Copyright © 2008 John Wiley & Sons, Ltd.

Microstructural and chemical studies of interfaces between Cu(In,Ga)Se2 and In2S3 layers

Microstructural and chemical properties of the interfaces between Cu(In,Ga)Se2 (CIGS) and In2S3 layers in dependence on the In2S3 deposition temperature and Na concentration were investigated. The In2S3 layers were deposited by atomic layer deposition on CIGS layers at substrate temperatures ranging from 140°C to 240°C. Interfaces were investigated by means of scanning electron microscopy, bright-field and high-resolution transmission electron microscopy, electron diffraction, and energy-dispersive x-ray spectrometry. An orientation relationship between CIGS {112) and In2S3 {103) planes was found for the sample deposited at 210°C, whereas no orientation relationship was detected for the 240°C sample. Cu diffusion from CIGS into In2S3 was detected, as well as Cu depletion and In enrichment on the CIGS side of the interface. All three effects are enhanced with increasing deposition temperature. These results indicate the formation of a buried junction in the CIGS layer. In addition, a Na-free solar cell was investigated. The results show that In2S3 grain sizes are smaller than in solar cells containing Na. Also, enhanced Cu and Ga diffusion from the CIGS absorber into the In2S3 buffer as well as enhanced Cu depletion and In enrichment on the CIGS side of the interface were detected. This may indicate that both Na and Cu occupy vacancies and In sites in the In2S3 tetragonal spinel structure.