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Evidence of the Ambipolar Behavior of Mo 6 Cluster Iodides in All-Inorganic Solar Cells: A New Example of Nanoarchitectonic Concept. ACS APPLIED MATERIALS & INTERFACES 2022; 14:1347-1354. [PMID: 34931797 DOI: 10.1021/acsami.1c17845] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ambipolar materials such as carbon nanotubes, graphene, or 2D transition metal chalcogenides are very attractive for a large range of applications, namely, light-emitting transistors, logic circuits, gas sensors, flash memories, and solar cells. In this work, it is shown that the nanoarchitectonics of inorganic Mo6 cluster-based iodides enable to form thin films exhibiting photophysical properties that enable their classification as new members of the restricted family of ambipolar materials. Thus, the electronic properties of the ternary iodide Cs2[{Mo6I8i}I6a] and those of thin films of the aqua-complex-based compound [{Mo6I8i}I4a(H2O)2a]·xH2O were investigated through an in-depth photoelectrochemical study. Once hole/electron pairs are created, the holes and electrons turn to be transported simultaneously in opposite directions, and their lifetimes exhibit similar values. The ambipolar properties were demonstrated via the integration of [{Mo6I8i}I4a(H2O)2a]·xH2O as light harvesters in an all-solid solar cell. A significant photoresponse with a typical diode characteristic clearly provides evidence of the simultaneous transfer and transport of holes and electrons within the [{Mo6I8i}I4a(H2O)2a]·xH2O layer. The ambipolar behavior results, on the one hand, from the confinement of electrons imposed by the nanometric size of the molecular metal clusters and, on the other hand, from the poor electronic interactions between clusters in the solid state. Such molecular structure-based layers lead naturally to an intrinsic semiconducting behavior.
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Carbon Dioxide Reduction to Methanol with a Molecular Cobalt‐Catalyst‐Loaded Porous Carbon Electrode Assisted by a CIGS Photovoltaic Cell**. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202100035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Electronic Structure of the CdS/Cu(In,Ga)Se 2 Interface of KF- and RbF-Treated Samples by Kelvin Probe and Photoelectron Yield Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2021; 13:7745-7755. [PMID: 33529003 DOI: 10.1021/acsami.0c20976] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Ambient-pressure Kelvin probe and photoelectron yield spectroscopy methods were employed to investigate the impact of the KF and RbF postdeposition treatments (KF-PDT, RbF-PDT) on the electronic features of Cu(In,Ga)Se2 (CIGSe) thin films and the CdS/CIGSe interface in a CdS thickness series that has been sequentially prepared during the chemical bath deposition (CBD) process depending on the deposition time. We observe distinct features correlated to the CBD-CdS growth stages. In particular, we find that after an initial CBD etching stage, the valence band maximum (VBM) of the CIGSe surface is significantly shifted (by 180-620 mV) toward the Fermi level. However, VBM positions at the surface of the CIGSe are still much below the VBM of the CIGSe bulk. The CIGSe surface band gap is found to depend on the type of postdeposition treatment, showing values between 1.46 and 1.58 eV, characteristic for a copper-poor CIGSe surface composition. At the CdS/CIGSe interface, the lowest VBM discontinuity is observed for the RbF-PDT sample. At this interface, a thin layer with a graded band gap is found. We also find that K and Rb act as compensating acceptors in the CdS layer. Detailed energy band diagrams of the CdS/CIGSe heterostructures are proposed.
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Influence of Sulfur Evaporation during or after KF-Post Deposition Treatment On Cu(In,Ga)Se 2/CdS Interface Formation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:46953-46962. [PMID: 32937069 DOI: 10.1021/acsami.0c12455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This work investigates the impact of the elemental sulfur evaporation during or after KF-post deposition treatment (KF-PDT) on the resulting Cu(In,Ga)Se2/chemical bath deposited(CBD)-CdS interface. Chemical composition of the various interfaces were determined through Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger spectroscopy (XAES). Cu(In,Ga)Se2 absorber which experienced KF-PDT in selenium atmosphere (KSe sample) exhibits the formation of the well-reported In-Se based topping layer. Additional exposure to elemental sulfur, resulting in KSe+S sample, induces the partial sulfurization of this overlayer and/or of the absorber. After short immersion into the CdS bath, the resulting In-rich surfaces of KSe and KSe+S are likely to turn into few atomic layers of Cd-In-(Se/S)-O whose [S]/[Se]+[S] ratio and O content depend on their respective post deposition treatment. In contrast, KF-PDT performed in S atmosphere does not show an In-rich surface, making the early stage of CdS growth similar to that observed on untreated CIGSe.
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Photocathode functionalized with a molecular cobalt catalyst for selective carbon dioxide reduction in water. Nat Commun 2020; 11:3499. [PMID: 32661340 PMCID: PMC7358214 DOI: 10.1038/s41467-020-17125-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 06/12/2020] [Indexed: 01/30/2023] Open
Abstract
Artificial photosynthesis is a vibrant field of research aiming at converting abundant, low energy molecules such as water, nitrogen or carbon dioxide into fuels or useful chemicals by means of solar energy input. Photo-electrochemical reduction of carbon dioxide is an appealing strategy, aiming at reducing the greenhouse gas into valuable products such as carbon monoxide at low or without bias voltage. Yet, in such configuration, there is no catalytic system able to produce carbon monoxide selectively in aqueous media with high activity, and using earth-abundant molecular catalyst. Upon associating a p-type Cu(In,Ga)Se2 semi-conductor with cobalt quaterpyridine complex, we herein report a photocathode complying with the aforementioned requirements. Pure carbon dioxide dissolved in aqueous solution (pH 6.8) is converted to carbon monoxide under visible light illumination with partial current density above 3 mA cm−2 and 97% selectivity, showing good stability over time. Photo-electrochemical reduction of carbon dioxide is a promising strategy to derive valuable products. Here, the authors show a photocathode able to produce carbon monoxide selectively in aqueous media with high activity using earth-abundant molecular catalyst.
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Abstract
Several new materials with four structure-types (e.g., Cu0.32In1.74Ga0.84S4 (CIGS4), Cu0.65In1.75Ga1.4S5 (CIGS5), Cu1.44In2.77Ga0.76S6 (CIGS6), and Cu1.1In2.49Ga1.8S7 (CIGS7)) have been evidenced in the Cu2S-In2S3-Ga2S3 pseudo-ternary system. All of them present a 2D structure built upon infinite 2/∞[InS2] layers ((InS6) octahedra sharing edges) on which condense on both sides mono-, bi-, or tri-2/∞[MS] layers ((MS4) tetrahedra (M = Cu, In, Ga) sharing corners). (M(Td))n-2(In(Oh))Sn slabs are separated from each other by a van der Waals gap, and subscript n refers to the number of sulfur layers within the building block. These compounds have the propensity to display stacking faults but also polymorphic forms. Their optical gap (ca. 1.7 eV) is quite similar to the one of the Cu(In0.7Ga0.3)S2 chalcopyrite absorbers used in tandem solar cells, and the major charge carriers are holes. This suggests that they might be very attractive for photovoltaic applications in thin film devices but also for photocatalysis.
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Composition-Dependent Passivation Efficiency at the CdS/CuIn 1- x Ga x Se 2 Interface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907763. [PMID: 31984586 DOI: 10.1002/adma.201907763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/24/2019] [Indexed: 06/10/2023]
Abstract
The bandgap of CuIn1- x Gax Se2 (CIGS) chalcopyrite semiconductors can be tuned between ≈1.0 and ≈1.7 eV for Ga contents ranging between x = 0 and x = 1. While an optimum bandgap of 1.34 eV is desirable for achieving maximum solar energy conversion in solar cells, state-of-the-art CIGS-based devices experience a drop in efficiency for Ga contents x > 0.3 (i.e., for bandgaps >1.2 eV), an aspect that is limiting the full potential of these devices. The mechanism underlying the limited performance as a function of CIGS composition has remained elusive: both surface and bulk recombination effects are proposed. Here, the disentanglement between surface and bulk effects in CIGS absorbers as a function of Ga content is achieved by comparing photogenerated charge carrier dynamics in air/CIGS and surface-passivated ZnO/CdS/CIGS samples. While surface passivation prevents surface recombination of charge carriers for low Ga content (x < 0.3; up to 1.2 eV bandgap), surface recombination dominates for higher-bandgap materials. The results thus demonstrate that surface, rather than bulk effects, is responsible for the drop in efficiency for Ga contents larger than x ≈ 0.3.
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In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells. J Vis Exp 2018. [PMID: 30346379 PMCID: PMC6235408 DOI: 10.3791/55897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.
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Crystal Chemistry, Optical-Electronic Properties, and Electronic Structure of Cd 1- xIn 2+2 x/3S 4 Compounds (0 ≤ x ≤ 1), Potential Buffer in CIGS-Based Thin-Film Solar Cells. Inorg Chem 2018; 57:12624-12631. [PMID: 30260231 DOI: 10.1021/acs.inorgchem.8b01771] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CdIn2S4 and In2S3 compounds were both previously studied as buffer layers in CIGS-based thin-film solar cells, each of them exhibiting advantages and disadvantages. Thus, we naturally embarked on the study of the CdIn2S4-In2S3 system, and a series of Cd1- xIn2+2 x/3S4 (0 ≤ x ≤ 1) materials were prepared and characterized. Our results show that two solid solutions exist. The aliovalent substitution of cadmium(II) by indium(III) induces a structural transition at x ≈ 0.7 from cubic spinel Fd3̅ m to tetragonal spinel I41/ amd that is related to an ordering of cadmium vacancies. Despite this transition, the variation of optical gap is continuous and decreases from 2.34 to 2.11 eV going from CdIn2S4 to In2S3 while all compounds retain an n-type behavior. In contrast with the Al xIn2-xS3 solid solution, no saturation of the gap is observed. Moreover, XPS analyses indicate a difference between surface and volume composition of the grains for Cd-poor compounds. The use of Cd1- xIn2+2 x/3S4 compounds could be a good alternative to CdIn2S4 and In2S3 to improve CIGS/buffer interfaces with a compromise between photovoltaic conversion efficiency and cadmium content.
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Finding Relevant Parameters for the Thin-film Photovoltaic Cells Production Process with the Application of Data Mining Methods. Mol Inform 2017; 36. [PMID: 28514114 DOI: 10.1002/minf.201600161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 04/28/2017] [Indexed: 11/08/2022]
Abstract
A data mining approach is proposed as a useful tool for the control parameters analysis of the 3-stage CIGSe photovoltaic cell production process, in order to find variables that are the most relevant for cell electric parameters and efficiency. The analysed data set consists of stage duration times, heater power values as well as temperatures for the element sources and the substrate - there are 14 variables per sample in total. The most relevant variables of the process have been found based on the so-called random forest analysis with the application of the Boruta algorithm. 118 CIGSe samples, prepared at Institut des Matériaux Jean Rouxel, were analysed. The results are close to experimental knowledge on the CIGSe cells production process. They bring new evidence to production parameters of new cells and further research.
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Effect of the KF post-deposition treatment on grain boundary properties in Cu(In, Ga)Se 2 thin films. Sci Rep 2017; 7:41361. [PMID: 28128351 PMCID: PMC5269666 DOI: 10.1038/srep41361] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/20/2016] [Indexed: 11/29/2022] Open
Abstract
Significant power conversion efficiency improvements have recently been achieved for thin-film solar cells based on a variety of polycrystalline absorbers, including perovskites, CdTe, and Cu(In,Ga)Se2 (CIGS). The passivation of grain boundaries (GBs) through (post-deposition) treatments is a crucial step for this success. For the case of CIGS, the introduction of a potassium fluoride post-deposition treatment (KF-PDT) has boosted their power conversion efficiency to the best performance of all polycrystalline solar cells. Direct and indirect effects of potassium at the interface and interface-near region in the CIGS layer are thought to be responsible for this improvement. Here, we show that also the electronic properties of the GBs are beneficially modified by the KF-PDT. We used Kelvin probe force microscopy to study the effect of the KF-PDT on the CIGS surface by spatially resolved imaging of the surface potential. We find a clear difference for the GB electronic properties: the KF-PDT increases the band bending at GBs by about 70% and results in a narrower distribution of work function values at the GBs. This effect of the KF-PDT on the GB electronic properties is expected to contribute to the improved efficiency values observed for CIGS thin-film solar cells with KF-PDT.
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Evaluation of different buffer materials for solar cells with wide-gap Cu2ZnGeSxSe4−x absorbers. RSC Adv 2017. [DOI: 10.1039/c7ra06438a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this work kesterite-type Cu2ZnGeSxSe4−x (CZGSSe) absorbers were coated with four different buffer layer materials: CdS, In2S3, Zn(O,S) and CdIn2S4.
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Impact of Annealing-Induced Intermixing on the Electronic Level Alignment at the In2S3/Cu(In,Ga)Se2 Thin-Film Solar Cell Interface. ACS APPLIED MATERIALS & INTERFACES 2016; 8:2120-2124. [PMID: 26716913 DOI: 10.1021/acsami.5b10614] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The interface between a nominal In2S3 buffer and a Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorber was investigated by direct and inverse photoemission to determine the interfacial electronic structure. On the basis of a previously reported heavy intermixing at the interface (S diffuses into the absorber; Cu diffuses into the buffer; and Na diffuses through it), we determine here the band alignment at the interface. The results suggest that the pronounced intermixing at the In2S3/CIGSe interface leads to a favorable electronic band alignment, necessary for high-efficiency solar cell devices.
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Direct Synthesis of ZnO Nanowires on Nanopatterned Surface by Magnetron Sputtering. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/cvde.201106920] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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The major surface-labeled alpha-galactosylated glycoprotein of pig endothelial cells is the beta1 integrin subunit. Transplant Proc 2000; 32:979-80. [PMID: 10936310 DOI: 10.1016/s0041-1345(00)01074-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Natural anti-Gal antibodies constitute 0.2% of intravenous immunoglobulin and are equally retained on a synthetic disaccharide column or on an immobilized natural glycoprotein. Transplant Proc 2000; 32:882-3. [PMID: 10936257 DOI: 10.1016/s0041-1345(00)01023-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
BACKGROUND Many patients with renal failure are condemned to long-term dialysis with little prospect of transplantation because they are highly sensitized with immunoglobulin G (IgG) directed against class I human leukocyte antigens (HLA) of virtually all donors. Xenotransplantation could represent an attractive solution providing their alloantibodies (alloAb) do not recognize porcine motifs. Hitherto there has been no in vivo demonstration of any cross-reactivity and the objective of this work was to investigate this problem using a technique of extracorporeal pig kidney perfusion as a model of clinical xenografting. METHODS Pig kidneys were perfused ex vivo with plasma from both a group of highly sensitized patients and healthy individuals. Sequential plasma samples were analyzed for the titer of anti-Galalpha1-3Gal antibody (Ab) (major natural xenoreactive Ab) by enzyme-linked immunosorbent assay and anti-HLA class I Ab against a cell panel. At the end of perfusion, kidneys were perfused with a citric acid buffer to elute bound Ab. RESULTS Galalpha1-3Gal Ab were shown to decrease rapidly in the plasma (in less than 10 min) and then reached a plateau. A fractional decrease in anti-HLA Ab was also found in some of the perfused plasma samples. Anti-Gal Ab were readily detected in all citric acid perfusates and anti-HLA Ab in 8 of 10. The HLA specificities of eluted Ab were mainly concordant with the originally designated specificities for each patient. CONCLUSION Anti-HLA class I Ab presumably cross-react with pig class I homologues. However, some plasma samples did not cross-react, suggesting that negatively cross-matched pig kidneys could be identified in the pig population for xenotransplantation in these patients. Further studies are required to precisely describe these cross-reactivities and to understand their functional significance in xenotransplantation.
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Abstract
A polyclonal antibody was raised against the Galalpha1-3Gal carbohydrate epitope, which is expressed by all mammals (except man and the closest primate species) by immunizing hens with rabbit erythrocyte membranes. IgY was isolated from egg yolks, and affinity-purified on a Galalpha1-3Gal-Synsorb column. Two percent of the initial IgY fraction was recovered. The specificity of the affinity-purified antibody was characterized by: absorption with human, rabbit and pig erythrocytes; by using Synsorb columns; by inhibition with different saccharides; and by immunostaining of glycolipids separated on thin layer chromatograms. A weak reactivity was found toward blood group B or blood group Pk determinant, depending on the assay system used. Such reactivities were abolished after absorption by the appropriate sorbents, yielding a polyclonal anti-Galalpha1-3Gal antibody with narrow specificity.
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