Enhancement in as-grown CuInSe2 film microstructure by a three potential pulsed electrodeposition method

P-type copper indium diselenide (CuInSe₂) films have been prepared onto ITO substrates by an electrodeposition method, that sequentially applies potential pulses at the deposition potential of each element Cu, Se and In, and then step it back in cyclically to induce the solid state reaction between the elements. Two electrolyte concentrations as well as three different pulse durations were assessed. The resulting films were compared with those deposited at fixed electrode potentials. As-grown films are nanocrystalline and have an E_g ～ 0.95 eV. Raman spectroscopy shows that Se and Cu–Se contents decrease while pulse duration increases and electrolyte concentration decreases. Cu–Se phases are even absent for films grown at the low electrolyte concentration. These results represent a great improvement in the film phase purity reducing the need of post-deposition treatments.     

Electrodeposition of CuInSe2 films by an alternating double-potentiostatic method using nearly neutral electrolytes

One step electrodeposition with an alternating double-potentiostatic(DPSED) program was used to prepare CuInSe₂ thin films in nearly neutral aqueous electrolytes with sodium citrate complex. Linear sweep voltammetry(LSV) was measured to probe voltammetric properties of electrolytes with respect to Cu, In and Se individual precursor and their mixed solutions. Compositional and structural characteristics of the as-deposited and annealed films at 400 °C in Ar atmosphere for 0.5 h were analyzed by XRD and XPS. The results showed that reduction of Cu²⁺ to Cu⁺ at one potential point of ?800 mV and subsequently formation of CuIn alloy as well as metal In and amorphous Se at the other potential point of ?1400 mV were responsible for synthesis of CISe chalcopyrite. Composition self-regulation made DPSED films have three elements co-deposition and more uniform element distribution, which promoted chalcopyrite CISe formation.     

Electrochemical growth of CuInSe<Subscript>2</Subscript> thin film on different substrates from alkaline medium. Characterization of the films

The simultaneous electrodeposition of the system Cu–In–Se was investigated. The study was carried out at pH 8.5 using diethylentriamine as complexing agent for the Cu⁺² ion. The synthesis of CuInSe₂ semiconductor thin films was carried out by electrodeposition on different substrates [indium–tin oxide (ITO) on glass, aluminum and type 304 steel]. The simultaneous codeposition of the Cu, In, and Se was achieved by constant potential electrolysis technique in aqueous solutions containing the elements that conform this material. The deposits of CuInSe₂ were about 4 μm thick, which is thick enough for the photovoltaic effect to take place. The as-deposited films were characterized by atomic emission spectroscopy with inductive coupling plasm (AES-ICP) and scanning electronic microscopy (SEM). Annealed films were characterized X-ray diffraction, optical NIR spectroscopy, and photoelectrochemical studies The films were obtained with a well-defined composition, very close to the expected one. Homogeneous deposit with chalcopyrite structure was produced. A In₂O₃ phase was also observed. Annealing of the film improved the crystallinity of the films. Good photo response, an appropriate absorption coefficient, and a band gap of 1.09 eV were obtained.     

离子液体电沉积CuInxGa1-xSe2薄膜

采用循环伏安法(CV)对离子液体Reline中三元CuCl₂+InCl₃+SeCl₄体系和四元CuCl₂+InCl₃+GaCl₃+SeCl₄体系的电化学行为进行了研究。研究表明,In³⁺并入三元CIS(Cu-In-Se)薄膜体系和Ga³⁺并入四元CIGS(Cu-In-Ga-Se)薄膜体系均有两种途径：一是发生共沉积,二是直接还原。利用电感耦合等离子体发射光谱(ICP)和扫描电镜(SEM)对沉积电势、镀液温度和主盐浓度对CIGS薄膜组成、镀层表面形貌的影响进行了测试,结果表明通过工艺参数的选择可以控制Ga/(Ga+In)和CIGS薄膜组成并得到化学计量比为Cu_1.00In_0.78Ga_0.27Se_2.13的薄膜。     

离子液体电沉积CuIn_xGa_(1-x)Se_2薄膜(英文)

采用循环伏安法(CV)对离子液体Reline中三元CuCl2+InCl3+SeCl4体系和四元CuCl2+InCl3+GaCl3+SeCl4体系的电化学行为进行了研究。研究表明,In3+并入三元CIS(Cu-In-Se)薄膜体系和Ga3+并入四元CIGS(Cu-In-Ga-Se)薄膜体系均有两种途径:一是发生共沉积,二是直接还原。利用电感耦合等离子体发射光谱(ICP)和扫描电镜(SEM)对沉积电势、镀液温度和主盐浓度对CIGS薄膜组成、镀层表面形貌的影响进行了测试,结果表明通过工艺参数的选择可以控制Ga/(Ga+In)和CIGS薄膜组成并得到化学计量比为Cu1.00In0.78Ga0.27Se2.13的薄膜。     

电沉积-退火工艺制备铜铟硒太阳能电池薄膜及表征

CuInSe₂ (CIS) films with good crystalline quality were synthesized by electrodeposition followed by annealing in Se vapor at 530 oC. The morphology, composition, crystal structure, optical and electrical properties of the CIS films were investigated by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, UV-VIS-NIR spectroscopy, and admittance spectroscopy. The results revealed that the annealed CIS films had chalcopyrite structure and consisted of relatively large grains in the range of 500-1000 nm and single grain of films extend usually through the whole film thickness. The band gap of CIS films was 0.98 eV and carrier concentration was in the order of 10¹⁶ cm^-3 after etching the Cu-Se compounds on the film surface. Solar cells with the structure of AZO/i-ZnO/CdS/CIS/Mo/glass were fabricated. Current density vs. voltage test under standard reported condition showed the solar cells with an area of 0.2 cm² had a conversion efficiency of 0.96%. The underlying physics was also discussed.     

A crystallographic description of experimentally identified formation reactions of Cu(In,Ga)Se2

This work describes solid-state reactions for the formation of the chalcopyrite compounds CuInSe₂, CuGaSe₂ and Cu(In,Ga)Se₂ on atomic scale. The most important chalcopyrite formation reactions which were identified by the authors by real-time in situ X-ray diffraction in preceding experiments are (A) CuSe+InSe→CuInSe₂, (B) Cu₂Se+2 InSe+Se→2 CuInSe₂ and (C) Cu₂Se+In₂Se₃→2 CuInSe₂. During the selenistaion of a metallic precursor containing gallium a separate fourth reaction occurs: (D) Cu₂Se+Ga₂Se₃→2 CuGaSe₂. The quaternary compound is finally formed by interdiffusion of CuInSe₂ with CuGaSe₂ (E). These five reactions differ in their activation energy and reaction speed. We explain these differences qualitatively by analysing the involved crystal structures for each reaction. It turns out that all reactions involved in the formation of Cu(In,Ga)Se₂ are promoted by epitaxial relations, which facilitates the formation of polycrystalline thin films at temperatures much below those necessary for single crystal growth. Recommendations for the growth of larger grains of Cu(In,Ga)Se₂ containing fewer defects are given.     

Toward Cost‐Effective Manufacturing of Silicon Solar Cells: Electrodeposition of High‐Quality Si Films in a CaCl2‐based Molten Salt

Electrodeposition of Si films from a Si‐containing electrolyte is a cost‐effective approach for the manufacturing of solar cells. Proposals relying on fluoride‐based molten salts have suffered from low product quality due to difficulties in impurity control. Here we demonstrate the successful electrodeposition of high‐quality Si films from a CaCl₂‐based molten salt. Soluble Si^IV−O anions generated from solid SiO₂ are electrodeposited onto a graphite substrate to form a dense film of crystalline Si. Impurities in the deposited Si film are controlled at low concentrations (both B and P are less than 1 ppm). In the photoelectrochemical measurements, the film shows p‐type semiconductor character and large photocurrent. A p–n junction fabricated from the deposited Si film exhibits clear photovoltaic effects. This study represents the first step to the ultimate goal of developing a cost‐effective manufacturing process for Si solar cells based on electrodeposition.     

Influence of electrodeposition conditions on the properties of CdTe films

The results of the influence of electrodeposition conditions on the structural, compositional, optical, and photoelectrochemical properties of CdTe thin films deposited in one-step electrochemical method are presented. The CdTe films were prepared electrochemically from aqueous acidic solution with low ratios of Cd²⁺ ions to Te(IV) ions concentration. Instead of commonly used TeO₂, water-soluble Na₂TeO₃ was used as a source of tellurium ions. The cathodic deposition of CdTe was performed at different constant potentials from solutions containing different cadmium and tellurium ions concentration. As-deposited CdTe thin films were studied by different analytical techniques. The X-ray photoelectron spectroscopy spectra exhibited CdTe formation on the electrode with some amount of tellurium oxides and cadmium oxides. The best quality CdTe deposits, free of TeO₂, were formed in bath containing excess of Cd²⁺ ions and at the potential of ?0.65 V vs. saturated calomel electrode, slightly more positive than E _eq of Cd/Cd²⁺ system. Structural X-ray diffraction studies revealed polycrystallinity of deposits with the highest content of the (111)-oriented cubic (111) form. Optical band gap energy values were found in the range from 1.36 to 1.6 eV for CdTe films prepared at various synthesis conditions. The preliminary photoelectrochemical studies have shown that the variation of the deposition potential as well as bath composition leads to the formation of p- or n-type CdTe films. As-deposited CdTe films were not stable in polysulfide solution under illumination.     

Effect of Anionic Electrolytes and Precursor Concentrations on the Electrodeposited Pt Structures

Electrodeposition of functional metal surfaces has received great attention because of their useful applications. Recently, interesting electrodeposition behavior of Pt at −0.8 V (vs. Ag/AgCl) was reported, where underpotential deposited H (H_upd) layers played a unique role in the electrodeposition. Here, we report the effect of anionic electrolytes and precursor concentrations on the electrochemical deposition behavior of Pt. Depending on these two experimental parameters, two distinct Pt structures, monolayer Pt films and Pt spheres, were electrodeposited at −0.8 V. In addition to the underpotential deposited H (H_upd) layers formed at −0.8 V, the adsorption of Cl⁻ also plays a significant role in determining the electrodeposited Pt structures. When the PtCl₄²⁻ concentration was low and the Cl⁻ concentration was high enough for the adsorption of PtCl₄²⁻ to be blocked by the H_upd and Cl⁻ layers, monolayer Pt films were electrodeposited. Otherwise, further electrodeposition of Pt spheres over the monolayer Pt films occurred. The effect of other halide ion adsorption and the controlled growth of Pt spheres during the Pt electrodeposition were also investigated. The electrochemical deposition behavior of Pt demonstrated in this work provides insight into the fabrication of functional Pt surfaces.     

Electrochemical deposition and characterization of SnS thin films

Thin films of SnS were cathodically deposited onto stainless steel substrates from bath containing 0.025 M SnSO₄, 0.25 M KSCN and 0.25 M Na₂SO₄. The mechanism of electrochemical co-deposition of tin and sulphur was investigated by cyclic voltammetry. Analysis of the chronoamperometric current–time transients suggested that, in the potential range −560 to −590 mV vs saturated calomel electrode, the electrodeposition of SnS involved progressive nucleation model. However, at a potential −600 mV, the electrodeposition involved instantaneous nucleation model. The deposits have been characterized by scanning electron microscopy, X-ray diffraction and optical measurements. SnS films were found to be polycrystalline with an optical energy gap of 1.38 eV.     

Thermische Zersetzung von CuInSe2, LiInSe2 und LiInTe2

The thermal decompositions of CuInSe₂, LiInSe₂ and LiInTe₂ in vacuum at high temperatures were studied by using TG/DTG coupled with mass spectrometry. For CuInSe₂, two steps were found to be significant. Up to 1000 °C Se₂ and In₂Se evaporate, followed later by Cu₂Se. The Li-containing compounds show similar behaviour. However, Li⁺ was already detected during the first step. Obviously, Li₂Se dissociates more readily than Cu₂Se. No Cu⁺ species were detected up to the complete evaporation of CuInSe₂.     

THEN FILM CELLS BASED ON CuInSe2

Abstract

Using thin film devices of the form CdS(n)/CuInSe₂(p) fabricated on electrodeposited CuInSe₂, electrical and optical measurements have been made. From temperature-dependent I-V measurements, it was observed that the recombination current became progressively more important as the temperature was decreased. Results of dark C-V measurements indicated that CuInSe₂ films with carrier concentrations in the range from 10¹⁵ to 10¹⁷ cm^?3 can be easily prepared using the electrodeposition method. Photoresponse of the devices was also measured, giving an essentially flat region in the range from 0.6 to 1.0 micron. At wavelengths beyond 1 micron, the quantum efficiency decreased continuously with the increase in the wavelength. This continuous decrease in the quantum efficiency could be due to the presence of interface states as suggested by the photo capacitance measurements.     

Electrodeposition of CuInSe<Subscript>2</Subscript> films onto a molybdenum electrode

Joint reduction of Cu(II), Se(IV), and In(III) ions at a molybdenum electrode from a solution based of sulfosalicylic acid solution was studied. The optimal range of potentials for deposition of the CuInSe₂ compound was chosen. The composition of the films obtained was confirmed by X-ray phase and electron microprobe analyses.     

Preparation and growth behavior of amorphous Pd40Ni40P20 film by electrodeposition

Amorphous Pd₄₀Ni₄₀P₂₀ alloy has potential applications in electronics and catalytic industry. In this paper, amorphous Pd₄₀Ni₄₀P₂₀ films were prepared by electrodeposition. Samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and profilometry. Voltammetric curves and potential–time transient indicate the leading role of Pd in the initial growth stage. Based on compositional, morphological, and electrochemical analyses, Pd₄₀Ni₄₀P₂₀ electrodeposition is regarded as Pd-induced PdNiP co-deposition accompanying with hydrogen evolution reactions.     

Investigating the Mechanism by Which Intragap States Tailor Light Emission: Case of Copper Deficient and Zn Doped Cu−In−Se Quantum Dots**

The large structural tolerance of I–III–VI group quantum dots (QDs) to off-stoichiometry allows their photoluminescence properties to be adjusted via doping, thereby enabling application in different fields. However, the photophysical processes underlying their photoluminescence mechanism remain significantly unknown. In particular, the transition channels of CuInSe₂ QDs, which are altered by intrinsic and extrinsic intragap states, remain poorly reported. Herein, we investigated the photophysical processes associated with intragap states via electrochemical and optical techniques by using copper deficient Cu−In−Se QDs as well as Zn doped Cu−In−Se QDs. When the Cu/In molar ratios of Cu−In−Se QDs increased from 0.3 : 1 to 0.9 : 1, the photoluminescence spectra displayed a red-shift from 700 nm to 1050 nm. Although there was a blue-shift after the introduction of Zn²⁺ dopants in Cu−In−Se QDs, a significant red-shift occurred (from 660 nm to 760 nm) when the Zn/Cu molar ratios decreased from 0.7 : 0.3 to 0.3 : 0.7. The Gaussian deconvolution results of the photoluminescence spectra and the band gap derived from absorption spectra by fitting supported the fact that the optical transition channels are dependent on the Cu/In and Zn/Cu molar ratios. After the introduction of the Zn²⁺ ions, the alloyed-resultant blue-shift of the emission spectra was observed, primarily due to the enlarged band gap; however, the radiative recombination of prominent intrinsic intragap states is still observed; and only a small proportion of the band-edge exciton undergoes recombination for the sample with low Zn content. Cyclic voltammetry measurements revealed well-defined extrinsic Zn_Cu intragap states (Zn substitution on Cu sites) and intrinsic Cu^x (x= 1+/2+) states in the band gap. The results presented here provide a better understanding of the varying effects of dopant on photoluminescence in terms of I–III–VI group QDs.     

Electrodeposition of selenium from 1-ethyl-3-methyl-imidazolium trifluromethylsulfonate

The electrodeposition of thin selenium (Se) films from 1-ethyl-3-methyl-imidazolium trifluromethylsulfonate at room and elevated temperatures on gold and on copper substrates was studied under open-air conditions. The effect of bath temperature on the composition and structure of the deposited films was examined using cyclic voltammetry, chemical analysis and X-ray diffraction analysis. The obtained results showed that on gold substrate and at room temperature, a reddish Se film grows mainly in amorphous, monoclinic, rhombohedral and hexagonal structure, while at temperatures ≥90 °C, a grayish film of hexagonal and rhombohedral structure is deposited. Photoelectron spectroscopy shows that both films consist of pure Se with only slight surface contaminations by remnants from the electrodeposition. Due to the differences in phase structure and the presence of the monoclinic phase, the reddish films showed higher light absorbance. The band gap of the reddish film is close to that of pure amorphous Se reported in literature. Deposition on copper substrate leads to formation of CuSe and CuSe₂ at room temperature and at 70 °C, respectively.     

(1,3‐Dimethylimidazolidine‐2‐selone‐κSe)bis(1,10‐phenanthroline‐κ2N,N′)copper(II) bis(perchlorate) and bis(2,2′‐bipyridyl‐κ2N,N′)(imidazolidine‐2‐thione‐κS)copper(II) bis(perchlorate)

In the first title salt, [Cu(C₁₂H₈N₂)₂(C₅H₁₀N₂Se)](ClO₄)₂, the Cu^II centre occupies a distorted trigonal–bipyramidal environment defined by four N donors from two 1,10‐phenanthroline (phen) ligands and by the Se donor of a 1,3‐dimethylimidazolidine‐2‐selone ligand, with the equatorial plane defined by the Se and by two N donors from different phen ligands and the axial sites occupied by the two remaining N donors, one from each phen ligand. The Cu—N distances span the range 1.980 (10)–2.114 (11) Å and the Cu—Se distance is 2.491 (3) Å. Intermolecular π–π contacts between imidazolidine rings and the central rings of phen ligands generate chains of cations. In the second salt, [Cu(C₁₀H₈N₂)₂(C₃H₆N₂S)](ClO₄)₂, the Cu^II centre occupies a similar distorted trigonal–bipyramidal environment comprising four N donors from two 2,2′‐bipyridyl (bipy) ligands and an S donor from an imidazolidine‐2‐thione ligand. The equatorial plane is defined by the S donor and two N donors from different bipy ligands. The Cu—N distances span the range 1.984 (6)–2.069 (7) Å and the Cu—S distance is 2.366 (3) Å. Intermolecular π–π contacts between imidazolidine and pyridyl rings form chains of cations. A major difference between the two structures is due to the presence in the second complex of two N—H...O hydrogen bonds linking the imidazolidine N—H hydrogen‐bond donors to perchlorate O‐atom acceptors.     

Electroreduction of Dy(III) assisted by Zn and its co-deposition with Zn(II) in LiCl–KCl molten salt

To recover dysprosium (Dy) from LiCl–KCl molten salt, the electrochemical mechanism of Dy(III) on liquid Zn electrode and co-deposition of Dy(III) and Zn(II) on W electrode were studied using electrochemical methods. Cyclic voltammetry results demonstrated that the redox process of Dy on liquid Zn electrode is reversible and controlled by diffusion. Reverse chronopotentiograms showed that the transition time ratio of reduction and oxidation is ~3:1, revealing the redox of Dy on liquid Zn electrode is a kind of soluble–soluble system: Dy(III) + 3e⁻ = (Dy–Zn)_solution. The half-wave potential of Dy(III) was almost constant with the increase in scanning rate. The electrochemical separation of metallic Dy from the molten salt was performed using constant potential electrolysis, and the product characterized using X-ray diffraction and scanning electron microscopy–energy-dispersive X-ray spectroscopy was the thermodynamic unstable compound DyZn₅. Also, the co-deposition mechanism of Dy(III) and Zn(II) was explored, indicating that Dy(III) could deposit on pre-deposited Zn and form Dy–Zn compounds: Zn(II) + 2e⁻ = Zn and xDy(III) + yZn + 3xe⁻ = Dy_xZn_y. Moreover, the effect of Dy(III) concentration on the formation of Dy–Zn compounds was investigated. The redox peak currents corresponding to different Dy–Zn compounds changed with the increase in Dy(III) concentration. The co-deposition of Dy(III) and Zn(II) was performed using constant current electrolysis at diverse Dy(III) concentrations. The different Dy–Zn compounds were produced by controlling Dy(III) concentration.     

一步法电化学沉积Cu(In1-x,Gax)Se2薄膜的特性

在CuCl2、InCl3、GaCl3及H2SeO3组成的酸性水溶液电沉积体系中, 对Mo/玻璃衬底上一步法电沉积Cu(In1-x, Gax)Se2(简写为CIGS)薄膜进行了研究. 为了稳定溶液的化学性质, 在溶液中加入邻苯二甲酸氢钾和氨基磺酸作为pH缓冲剂, 将溶液的pH值控制在约2.5, 并提高薄膜中Ga的含量. 通过大量实验优化了溶液组成及电沉积条件, 得到接近化学计量比贫Cu 的CIGS薄膜(当Cu与In+Ga的摩尔比为1时, 称为符合化学计量比的CIGS薄膜; 当其比值为0.8-1时, 称为贫Cu或富In的CIGS 薄膜)预置层, 薄膜表面光亮、致密、无裂纹. 利用循环伏安法初步研究了一步法电沉积CIGS薄膜的反应机理, 在沉积过程中, Se4+离子先还原生成单质Se, 再诱导Cu2+、Ga3+和In3+发生共沉积. 电沉积CIGS薄膜预置层在固态硒源280 ℃蒸发的硒气氛中进行硒化再结晶, 有效改善了薄膜的结晶结构, 且成份基本不发生变化,但是表面会产生大量的裂纹.