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. 相似文献
Structures of compounds in the Cu2Se-In2Se3-Ga2Se3 system have been investigated through X-ray diffraction. Single crystal structure studies for the so-called stoichiometric compounds Cu(In,Ga)Se2 (CIGSe) confirm that the chalcopyrite structure (space group I4¯2d) is very flexible and can adapt itself to the substitution of Ga for In. On the other hand a structure modification is evidenced in the Cu1−z(In0.5Ga0.5)1+z/3Se2 series when the copper vacancy ratio (z) increases; the chalcopyrite structure turns to a modified-stannite structure (I4¯2m) when z≥0.26. There is a continuous evolution of the structure from Cu0.74(In0.5Ga0.5)1.09Se2 to Cu0.25(In0.5Ga0.5)1.25Se2 ((i.e. Cu(In0.5Ga0.5)5Se8), including Cu0.4(In0.5Ga0.5)1.2Se2 (i.e. Cu(In0.5Ga0.5)3Se5). From this single crystal structural investigation, it is definitively clear that no ordered vacancy compound exists in that series. X-ray photoemission spectroscopy study shows for the first time that the surface of powdered Cu1−z(In0.5Ga0.5)1+z/3Se2 compounds (z≠0) is more copper-poor than the bulk. The same result has often been observed on CIGSe thin films material for photovoltaic applications. In addition, optical band gaps of these non-stoichiometric compounds increase from 1.2 to 1.4 eV when z varies from 0 to 0.75. 相似文献
Mo(SexSy) is a transition metal dichalcogenide typically applied as a back contact interlayer in Cu(In,Ga)(Se,S)2 (CIGSSe) solar cells. Band alignment at the buried Mo/CIGSSe junction mediated by Mo(SexSy) is important for current transport and enables quasi-ohmic behavior between the CIGSSe absorber and the Mo back electrode. Furthermore, the S/(Se + S) ratio is a crucial parameter that determines the height of the valence band offset at the CIGSSe/Mo(SexSy) interface. Because the interlayer is formed during rapid thermal processing, an MoSe2 or MoS2 thin film grown on free substrate surfaces will not be representative for a realistic solar cell device. Thus, for fundamental thin-film material analysis, as well as functional characterization and modeling, appropriate preparation and analytical techniques are required in order to prevent artifacts. In principal, the weak van der Waals forces between two-dimensional stacked Mo(SexSy) sheets allow the implementation of exfoliation procedures to generate free Mo(SexSy) surfaces out of CIGSSe solar cell layer stacks. In this article, two different exfoliation-based Mo(Sex,Sy) preparation methods are investigated and evaluated with respect to subsequent surface analytical characterization by X-ray and ultraviolet photoelectron spectroscopy. A special focus is laid on an artifact-free characterization of chemical and electronical properties of the exposed layers for a number of samples. In a first instance, the compositional Se/S and (Se + S)/Mo ratios at the surface are quantitatively analyzed on the basis of dedicated peak-fitting routines. Artifacts from carbonaceous contamination due to different exfoliation glues can be prevented through a detailed comparative analysis of carbon 1s and KLL Auger peaks. Furthermore, a significant surface band bending is observed that can be reduced by low-energy Ar ion in situ sputtering. A simple model for the sputter removal of a charged surface layer is presented, which allows to approximately calculate the absolute valence band maximum (VBM) positions required for band alignment and numerical device simulations. The presented exfoliation surface analysis methodology is important for the whole CIGS(Se) solar cell community and may be of general interest for emerging applications of further 2D transition metal dichalcogenides as well. 相似文献
The voltammetric responses of copper and silver had been extensively studied and compared in a variety of non-aqueous solvents
such as acetonitrile (AN), propylene carbonate (PC) and sulfolane containing two different supporting electrolytes namely
triethylaminetrishydrogen fluoride (TEA.3HF) and tetrabutylammonium tetrafluoroborate (TBABF4). The dissolution rate and surface transformation on the electrode surfaces as a result of anodic polarization was investigated
using atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM), respectively. In solvent-free TEA.3HF medium,
the copper electrode shows high charge recovery ratio (Qc/Qa), and the difference between the initial anodic and cathodic potentials, obtained at a current density of 2 mA cm−2, is around 0.11 V, suggesting that in this medium, Cu can certainly serve as reference electrode. On the other hand, on Ag
electrode, substantial dissolution was observed leading to very high anodic (Qa) and cathodic (Qc) charges, and the surface morphology after the cyclic polarization results in roughened surface with large pores. The effects
of incorporating AN and water as additives in TEA.3HF on the solubility and stability of these metal fluoride films are also
reported. The dissolution pattern and film formation behavior of these two metals in the different solvents containing fluoride
and fluoroborate ionic species have several qualitative similarities, as noted from cyclic voltammetry responses and SEM morphology.
Anodic dissolution and precipitation process for both Cu and Ag depends significantly on the nature of supporting electrolytes
as well as solvents. In AN containing 0.1 M TEA.3HF, the dissolution of Cu and Ag electrodes was very high. Fluoride salts
of Cu show lesser solubility than Ag in those solvents, while fluoroborate salts exhibit the reverse trend. The AAS data suggest
that for a particular salt, which may be either fluoride or fluoroborate of Cu and Ag, the relative solubility decreases in
the order AN > PC > sulfolane. 相似文献
The Cu3Se2 nanofilms were synthesized with underpotential deposition based electrochemical codeposition technique for the first time in the literature. The electrochemical behaviors of copper and selenium were investigated in 0.1 M H2SO4 on Au electrode. The effects of concentration and scan rate on the electrochemical behavior of selenium were studied. The electrochemical behaviors in underpotential deposition and bulk regions of the Cu-Se system were investigated in acidic solution by cyclic voltammetry and electrolysis techniques. X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and ultraviolet and visible absorption spectroscopy techniques were used for characterization of synthesized films. According to the X-ray photoelectron spectroscopy spectrum, Cu/Se ratio was determined to be approximately 3/2. Copper selenide nanofilms are two phases and polycrystalline according to X-ray diffraction. The films mainly formed tetragonal Cu3Se2 (umangite mineral structure) structure and the particle size was approximately 45.95 nm. Scanning electron microscopy images showed that Cu3Se2 nanofilms consisted of uniform, nano-sizes and two-dimensional. It was found through AFM that the surface roughness of the film was 6.173 nm, with a mean particle size of around 50 nm. Depending on the deposition time, the band gaps of the Cu3Se2 films were in the range of 2.86–3.20 eV. Three characteristic vibrational modes belonging to Cu3Se2 nanofilms were recorded in the Raman spectrum. 相似文献
The effects of surface modification and reaction conditions on the photoelectrochemical properties of polycrystalline Cu(In,Ga)Se2 (CIGS) thin films for water splitting were studied. CIGS modified with platinum particles (Pt/CIGS) generated a cathodic photocurrent at potentials up to + 0.4 V vs. RHE at pH = 9.5. The photocurrent was stable for 16 h, which resulted in a turnover number of over 500. A CdS-inserted film (Pt/CdS/CIGS) had significantly improved properties compared to Pt/CIGS: a 0.3 V higher onset potential of cathodic photocurrent and a three-fold increase in the quantum efficiency. Our results suggest the feasibility of CIGS as a photocathode for biphotoelectrochemical water splitting. 相似文献
CuIn1–xGaxSe2 [CIGS; x=Ga/(In+Ga)] thin films are among of the best candidates as absorber materials for solar cell applications. The material quality and main properties of the polycrystalline absorber layer are critically influenced by deviations in the stoichiometry, particularly in the Cu/(In+Ga) atomic ratio. In this work a simple, sensitive and accurate method has been developed for the quantitative determination of these thin films by inductively coupled plasma optical emission spectrometry (ICP-OES). The proposed method involves an acid digestion of the samples to achieve the complete solubilization of CIGS, followed by the analytical determination by ICP-OES. A digestion procedure with 50% HNO3 alone or in the presence of 10% HCl was performed to dissolve those thin films deposited on glass or Mo-coated glass substrates, respectively. Two analytical lines were selected for each element (Cu 324.754 and 327.396 nm, Ga 294.364 and 417.206 nm, In 303.936 and 325.609 nm, Se 196.090 and 203.985 nm, and Mo 202.030 and 379.825 nm) and a study of spectral interferences was performed which showed them to be suitable, since they offered a high sensitivity and no significant inter-element interferences were detected. Detection limits for all elements at the selected lines were found to be appropriate for this kind of application, and the relative standard deviations were lower than 1.5% for all elements with the exception of Se (about 5%). The Cu/(In+Ga) atomic ratios obtained from the application of this method to CIGS thin films were consistent with the study of the structural and morphological properties by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 相似文献
[Ga(en)3][Ga3Se7(en)] · H2O: A Gallium Chalcogenide with Chains of [Ga3Se6Se2/2(en)]3– Bicycles The new selenidogallate [Ga(en)3][Ga3Se7(en)] · H2O ( I ) was produced from a ethylendiamine suspension of Ga and Se at 130 °C. I crystallizes in the orthorhombic space group Pna21 with unit constants a = 1347.9(3) pm, b = 961.6(1) pm, c = 1967.6(4) pm and Z = 4. The crystal structure contains an anion so far not observed in gallium chalcogenides. It is built from [Ga3Se6Se2/2(en)]3– bicycles of three GaIIIL4 tetrahedra (L = en, Se) connected via selenium corners to linear chains. The cations, GaIII ions coordinated by three ethylendiamine in a distorted octahedral geometry are positioned in the holes of the hexagonal rod packing of these chains. 相似文献
A novel approach based on sol–gel spin coating method to deposit Zn(O,S) thin film using thiourea(TU) as a sulfur source replacing CdS as buffer layer was developed and the influence of TU concentration on the properties of Zn(O,S) thin films and Cu(In,Ga)Se2(CIGS) solar cells were investigated in this paper. It was found by X-ray diffraction and X-ray photoelectron spectroscopy that sol–gel derived Zn(O,S) thin films were amorphous and composed of ZnS, ZnO as well as Zn(OH)2. The variation of the optical band gap as a function of the S/(S+O) ratio was determined by energy-dispersive spectroscopy and UV-VIS-NIR. The results indicated that the minimum value for band gap of approximate 3.72?eV was obtained when the S/(S+O)?=?0.44. Efficiency of up to 7.28% was achieved for a CIGS solar cell with Zn(O,S) buffer layer from 0.2M TU, which was attributed to the optimized conduction band offset (CBO) of +0.45?eV at the CIGS/Zn(O,S) interface.
Zn(O,S) thin films prepared in sol–gel route was used to replace traditional CdS buffer layer deposited by chemical bath deposition method in Cu(In,Ga)Se2 solar cells. The best efficiency was achieved for CIGS/Zn(O,S)/i-ZnO/ITO heterostructure solar cell with S/(S+O)?=?0.18, which was attributed to the optimized conduction band offset (CBO) of +0.45?eV at the CIGS/Zn(O,S) interface.
The title centrosymmetric CuII binuclear complex, bis(μ‐N,N‐diethyl‐1,1‐diselenocarbamato‐Se,Se′:Se)bis[(N,N‐diethyl‐1,1‐diselenocarbamato‐Se,Se′)copper(II)], [Cu(Se2CNEt2)2]2 or [Cu2(C5H10NSe2)4], is built from two symmetry‐related [Cu{Se2CN(Et)2}2] units by pairs of Cu—Se bonds. The coordination geometry at the unique Cu atom is distorted square pyramidal, with Cu—Se distances in the range 2.4091 (11)—2.9095 (10) Å. 相似文献
Bovine serum albumin (BSA)‐conjugated MxSey (M=Ag, Cd, Pb, Cu) nanomaterials with different shapes and sizes were synthesized in water at room temperature by a protein‐directed, solution‐phase, green synthetic method. The method features very low energy consumption and nontoxic reagents with high yields of concentrated nanoparticles. The obtained bioconjugated nanoparticles have good dispersibility, bioactivity, and biocompatibility. In addition, various functional groups of protein on the surface of the nanocrystals are suitable for further biological interactions or couplings, which is very important for further biological applications. 相似文献
Multicomponent copper-containing CuI-AsI3-As2Se3 and CuI-Sb3I-As2Se3 chalcogenide films were produced by chemical deposition from solutions of chalcogenide glasses in n-butylamine and their electrical conductivity was studied. It was shown that the electrical properties of chalcogenide glasses and films based on these glasses have the same values within experimental error. It was found sing Mossbauer spectroscopy that antimony atoms are in the Sb(III) state in the environment of three selenium atoms, and copper ions in the Cu(I) state and are surrounded by iodine atoms. The chalcogenide films can be used to fabricate ion-selective electrodes sensitive to copper cations. 相似文献
Treatment of the digallium compound R2Ga–GaR2 [ 1 , R = CH(SiMe3)2] with a broad variety of functionalized carboxylic acids in the presence of water yielded μ‐hydroxo‐μ‐carboxylatodigallium compounds ( 2 – 10 ) containing intact Ga–Ga bonds in high to moderate yields. The compounds form dimeric formula units in which the unsupported Ga–Ga bonds are bridged by two hydroxo and two carboxylato ligands. Each gallium atom is terminally coordinated by a bulky alkyl group. NMR spectroscopy revealed mixtures of two isomeric compounds in solution in all cases. The second component may show a different bridging mode with each Ga–Ga bond bridged by a bidentate carboxylato ligand to form Ga2O2C five‐membered heterocycles. 相似文献
Tyrrellite, a naturally occurring Co–Ni–Cu selenide, has been studied by single‐crystal X‐ray diffraction. It possesses the normal spinel‐type structure, with Cu occupying the tetrahedral site and (Co+Ni) the octahedral site. The average Cu—Se distance of 2.3688 (2) Å is close to that of 2.3703 (8) Å in CuCr2Se4, whereas the average (Co+Ni)—Se distance of 2.3840 (1) Å appears to be slightly shorter than most octahedral Co—Se or Ni—Se distances (∼2.40–2.50 Å) in other selenides. The refined structure provides a basis for a redefinition of the ideal chemical formula of tyrrellite, which should be Cu(Co,Ni)2Se4, rather than the previously suggested (Cu,Co,Ni)3Se4. 相似文献
A new organically templated indium selenide, [C6H16N2][In2Se3(Se2)], has been prepared hydrothermally from the reaction of indium, selenium and trans-1,4-diaminocyclohexane in water at 170 °C. This material was characterised by single-crystal and powder X-ray diffraction, thermogravimetric analysis, UV-vis diffuse reflectance spectroscopy, FT-IR and elemental analysis. The compound crystallises in the monoclinic space group C2/c (a=12.0221(16) Å, b=11.2498(15) Å, c=12.8470(17) Å, β=110.514(6)°). The crystal structure of [C6H16N2][In2Se3(Se2)] contains anionic chains of stoichiometry [In2Se3(Se2)]2−, which are aligned parallel to the [1 0 1] direction, and separated by diprotonated trans-1,4-diaminocyclohexane cations. The [In2Se3(Se2)]2− chains, which consist of alternating four-membered [In2Se2] and five-membered [In2Se3] rings, contain perselenide (Se2)2− units. UV-vis diffuse reflectance spectroscopy indicates that [C6H16N2][In2Se3(Se2)] has a band gap of 2.23(1) eV. 相似文献
The thermal decomposition of copper sulphate hydroxide hydrate, (CuO·CuSO4). 2Cu(OH)2·H2O, to copper oxysulphate and CuO was investigated by X-ray phase analysis, IR spectroscopy, complex thermal analysis and electron microscopy. The effect of water vapour and time of treatment on the formation of decomposition products with a large surface area is studied. The strong decrease in specific surface area of the precipitate (from 80 m2/g to 20 m2/g) thermally treated at a temperature above 250°C is associated with the elimination of water having a coordination bond with the Cu2+ ion. During this process, the interplanar distances of the crystal lattice of copper sulphate hydroxide hydrate decrease. The time of decomposition of this compound essentially affects the decrease of the specific surface area. When the decomposition proceeds in an atmosphere containing water vapour sintering processes are predominating and the phase obtained has a considerably smaller specific surface area than in cases of decomposition under dry air. 相似文献