Martha Ch. Lux-Steiner

Martha Ch. Lux-Steiner
Helmholtz-Zentrum Berlin | HZB

Prof. Dr.

About

648
Publications
59,543
Reads
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14,035
Citations
Additional affiliations
August 1995 - March 2016
Freie Universität Berlin
Position
  • Professor (Full)
August 1995 - March 2016
Helmholtz-Zentrum Berlin
Position
  • Research Director
March 1980 - July 1995
Universität Konstanz
Position
  • Senior Researcher

Publications

Publications (648)
Article
A UHV-transferred Cu(In,Ga)Se2 (CIGSe) thin film prepared by a three-stage process on an Mo-coated float glass was successfully investigated by detailed UPS/XPS and directly compared with air-transferred and cyanide etched samples from the same batch. Besides the fact that the valence band maximum of the UHV-transferred sample is located 1.19 eV be...
Conference Paper
Full-text available
The influence of a KF-treatment of Cu(In,Ga)Se2 absorbers alone, without the influence of an excessive Se atmosphere and Na from the glass substrate has been studied. K-induced surface modifications differed for varying [K]/([In]+[Se]) (KIS) concentration ratios with a low KIS (0.74) absorber having a K-alloyed CIGSe surface growth and a high KIS (...
Article
A procedure to fabricate CuInSe2 (CISe) micro-absorbers and solar cells for concentrator applications is presented. The micro-absorbers are developed from indium precursor islands, which are deposited on a molybdenum coated glass substrate (back contact), followed by deposition of copper on top and subsequent selenization as well as selective etchi...
Article
Na and K metals have been evaporated on a Cu(In,Ga)Se2 (CIGSe) thin film solar cell absorber at 400 °C in order to investigate the effect of alkali metal incorporation on the very near-surface (up to 5 nm) region of the CIGSe absorber using soft X-ray spectroscopy techniques, focusing on the main compositional and electronic modifications of the ab...
Article
Thin film solar cells based on the kesterite material with the general composition Cu2ZnSn(Se,S)4 can be a substitute for the more common chalcopyrites (Cu(In,Ga)(Se,S)2) with a similar band gap range. When replacing the anion sulfide with selenide, the optical band gap of kesterite changes from 1.5 to 1 eV. Here we report on a study of the valence...
Article
Inkjet printing is a promising route for thin film deposition due to its low material wastage and potential of high throughput production. In this work, the inkjet printing technique is used for the deposition of Cu2ZnSn(SxSe1-x)4 (CZTSSe) thin films from Cu-Zn-Sn-S molecular inks. The key step for using the inkjet printing technique is to formulat...
Article
Full-text available
Ag nanoparticles have attracted interest for plasmonic absorption enhancement of solar cells. For this purpose, well-defined particle sizes and densities as well as very low deposition temperatures are required. Thus, we report here a new spray chemical vapour deposition method for producing Ag NP films with independent size and density control at...
Article
Light concentration has proven beneficial for solar cells, most notably for highly efficient but expensive absorber materials using high concentrations and large scale optics. Here, we investigate the light concentration for cost-efficient thin-film solar cells that show nano- or microtextured absorbers. Our absorber material of choice is CuIn; GaS...
Article
Vacuum free, solution based routes to the preparation of chalcopyrite absorbers for solar cells promise options in device design and manufacturing that are not provided by the standard vacuum based approaches. In order to fully exploit these options, the precursor should contain neither nanoparticles nor hazardous chemicals, and it should be stable...
Article
Full-text available
Ultra-thin perovskite absorber layers have attracted increasing interest since they are suitable for application in semi-transparent perovskite and tandem solar cells. In this study, size and density controlled plasmonic silver nanoparticles are successfully incorporated into ultra-thin perovskite solar cells through a low temperature spray chemica...
Article
This work focuses on the fabrication of stoichiometric CuInSe2 nanostructures with controllable physical parameters of the nanocrystals suitable for hybrid organic/inorganic photovoltaics. CuInSe2 nanostructures were prepared by the chemical close-spaced vapor transport (CCSVT) method onto Mo/barrier/glass substrates by using an In2Se3 source mater...
Article
We demonstrate that a simple and low-cost industrial sputter process can be used to substitute the InxSy:Na buffer and intrinsic ZnO layer with a single film of Zn(O,S). Cu(In,Ga)(Se,S)2 (CIGS) modules with an aperture area of 667 cm² and efficiencies up to 15.6% were prepared using a sputtered Zn(O,S) buffer layer. In comparison with our InxSy:Na...
Article
In this work we fabricate all-vacuum processed methyl ammonium lead halide perovskite by a sequence of physical vapor deposition of PbI2 and chemical vapour deposition (CVD) of CH3NH3I under a static atmosphere. We demonstrate that for higher deposition rate the (001) planes of PbI2 film show a higher degree of alignment parallel to the sample's su...
Article
Full-text available
Although Cu(In,Ga)(S,Se)2 (CIGSe) based thin film solar cells have reached efficiencies exceeding 22% based on vacuum processed CIGSSe absorbers, the supply of indium and gallium might become an issue if CIGSSe thin-film solar cells are produced in very large volumes. It is therefore mandatory to reduce the wastage of indium and gallium during the...
Article
Full-text available
The impact of the potassium fluoride post deposition treatment on CIGSe chalcopyrite absorbers is investigated by means of depth resolved hard x-ray photoemission spectroscopy of the near surface region. Two similar, slightly Cu-poor CIGSe absorbers were used with one being treated by potassium fluoride prior to the chemical bath deposition of an u...
Article
For a long time, it has been assumed that recombination in the space-charge region of copper-indium-gallium-selenide (CIGS) is dominant, at least in high efficiency solar cells with low band gap. The recent developments like potassium fluoride post deposition treatment and point-contact junction may call this into question. In this work, a theoreti...
Article
Full-text available
A bottom-up approach is presented for the production of arrays of indium islands on a molybdenum layer on glass, which can serve as micro-sized precursors for indium compounds such as copper- indium-gallium-diselenide used in photovoltaics. Femtosecond laser ablation of glass and a subsequent deposition of a molybdenum film or direct laser processin...
Article
Recyclable gold nanocatalysts with controllable morphology are in-situ formed on the solid substrate by a facile ultrasonic spray pyrolysis method. The Au nanoparticles on Mo substrates form spheres, while on Si icosahedra, or after addition of Cu ions to the precursor solution, decahedra are obtained. The catalytic properties are studied for the r...
Article
Full-text available
We report a route to deposit In2S3 thin films from air-stable, low-cost molecular precursor inks for Cd-free buffer layers in chalcopyrite-based thin film solar cells. Different precursor compositions and processing conditions were studied to define a reproducible and robust process. By adjusting the ink properties, this method can be applied in di...
Article
Full-text available
The CuInSe 2 and CuSbSe 2 ternary compounds and alloys of the (CuSbSe 2 ) 1-x ·(CuInSe 2 ) x system with the mole fraction of CuInSe 2 (x) equal to 0.05, 0.15, 0.25, 0.375, 0.50, 0.625, 0.75, 0.85, and 0.95 were prepared and the phase relations in this system were investigated by X-ray powder diffraction, optical microscopy, and scanning electron m...
Article
Full-text available
Kesterite Cu2ZnSn(S,Se)4 absorber layers with different [S]/([S]+[Se]) ratios were studied using XPS, UPS, Hard X-ray (HIKE) photoemission and the Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS). The samples were prepared by IREC using sequentially sputtered metallic precursor stacks with metal ratios of [Cu]/([Zn]+[Sn])=0.80, [Zn]/...
Conference Paper
Full-text available
Inkjet printing technique is a material-conserving technique, which can greatly reduce the production cost by reducing the wastage of materials during the deposition. Additionally, this method can be easily adapted to Roll-to-Roll processing for large-scale application. The most challenging issues that remain open for multi-component system such as...
Article
Full-text available
CH3NH3PbI3 layers chemically stabilized with poly(methyl methacrylate) (PMMA), relevant for photovoltaic applications, have been investigated by modulated surface photovoltage (SPV) spectroscopy at temperatures (T) between -182 and 60 °C. SPV is sensitive only to the PMMA/CH3NH3PbI3 interface region where photogeneration and charge separation take...
Conference Paper
The intension of the presented research action is to overcome resource-economic bottlenecks of the further technological development and market rollout of CIGS PV Products. In general it is envisaged to find possibilities to use precursor material with element specific purity levels. Therefore it is indispensable to know more about which level of e...
Conference Paper
Full-text available
Spectral and time dependent surface photovoltage (SPV) measurements were performed on Cu 2 ZnSn(S x Se 1-x) 4 (CZTSSe) thin films prepared on ITO/glass substrates by spray pyrolysis at ambient atmosphere from aqueous solutions and subsequent selenization of Cu 2 ZnSnS 4 (CZTS) layers. The morphology, stoichiometry and phases of the crystalline thin...
Conference Paper
Full-text available
FP7-CHEETAH is a combined collaborative project (CP) and coordination and support action (CSA) funded under the European Commission’s 7th Framework program and coordinated by ECN, NL with the aims to solve specific R&D issues and to overcome fragmentation of European PV R&D by intensifying the collaboration between R&D providers and industry to acc...
Article
Full-text available
The influence of absorber grain boundaries on the photocurrent transport in chalcopyrite based thin film solar cells has been calculated using a two dimensional numerical model. Considering extreme cases, the variation in red response is more expressed than in one dimensional models. These findings may offer an explanation for the strong influence...
Article
Full-text available
Modulated surface photovoltage (SPV) spectra have been correlated with the phase composition in layers of CH3NH3PbI3 (MAPbI3) prepared from MAI and PbCl2 and annealed at 100 °C. Depending on the annealing time, different compositions of MAPbI3, MAPbCl3, MACl, PbI2, and an un-identified phase were found. It has been demonstrated that evaporation of...
Conference Paper
In this work, we present the deposition of Cu2ZnSn(S,Se)4 CZTSSe absorbers by inkjet printing and their application in thin film solar cells. Inkjet printing is a promising approach, which can be easily adapted for industrial production. An attractive issue when using inkjet printing is its little demand on materials and low waste production during...
Article
Manufacturing chalcopyrite thin film solar cells from cost-efficient and environmentally friendly materials is of high priority. Therefore, the materials used in buffer layer production nowadays (such as indium and cadmium) need to be substituted. Zn(O,S) is considered to be a potential buffer layer material when deposited with a fast and inexpensi...
Article
Ternary CuInSe2 and quaternary Cu(In,Ga)Se2 chalcopyrite semiconductor films with potential applications as solar absorbers were deposited by single-step electrochemical deposition (ECD) on molybdenum coated glass substrates. The films have been structurally characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) combined with...
Article
We have investigated a specially grown Cu(In,Ga)Se2 (CIGSe) absorber, which was deposited by co-evaporation of Cu, In, Ga, and Se using a modified three stage process. Prior to the growth, the molybdenum-coated glass substrate was covered by a bent shroud made from tantalum (Ta), leading to a wedged absorber structure with a width of about 2 mm whe...
Article
ZnO and ZnS nanodots deposited by simple, non-vacuum ultrasonic spray methods, spray pyrolysis and ion layer gas reaction, are used to control the nucleation and thereby the morphology of electrochemically grown ZnO nanorod arrays. The ZnO nanodot density and subsequently the density of electrochemically deposited ZnO nanorods is increased by incre...
Article
The effect of varying the boron and aluminium content of the starting electrolyte for extrinsically doped ZnO films grown on SnO2:F substrates by electrochemical deposition was investigated. The ZnO:B film surface was characterised by grains with mainly hexagonal faces exposed while the exposed faces of the ZnO:Al grains were rectangular. Whereas a...
Article
Thin film solar cells already benefit from significant material- and energy savings. By using photon management, the conversion efficiency and the power density can be enhanced further, including reduction of material costs. In this work, micrometer-sized Cu(In,Ga)Se2 (CIGS) thin film solar cells were investigated under concentrated (up to 50x) whi...
Article
In2S3 thin layers can be prepared by Spray-ILGAR® (Ion Layer Gas Reaction) from indium trichloride or from indium triacetylacetonate solutions. In the first case, the film contains a controllable amount of Cl. The concentration of H2O or Cl was varied systematically in the precursor solutions that were used for the deposition of In2S3 buffer layers...
Article
Full-text available
Defect states in Cu 2ZnSn(SxSe1−x)4 thin films with x = 0.28, 0.36, and 1 were studied by combining photoluminescence (PL) and modulated surface photovoltage (SPV) spectroscopy. A single broad band emission in the PL spectra was observed and can be related to quasi-donor-acceptor pair transitions. The analysis of the temperature dependent quenching...
Article
In thispaper,wepresentthefabricationofCu2ZnSn(S, Se)4 (CZTSSe) thin film absorbersbyafour-step solution processbasedonZnS,SnSandCu3SnS4 nanoparticle precursorsandtheirapplicationinthin film solarcells.Theinfluence ofligand-exchangeprocessonthemorphologiesoftheresultingCZTSSe thin films wasstudied.Ligandexchangewitheachsequentialspuncoatlayersleadst...
Article
The interface between CuInSe2 and i-ZnO as it is needed for new chalcopyrite concepts like superstrate and tandem solar cells is investigated with X-ray photoelectron spectroscopy. A specially developed preparation permits depth profiling of the underlying i-ZnO layer. Thereby, interfacial reactions are revealed by tracing the diffusion of Cu, In a...
Article
Zinc oxide (ZnO) nanorod arrays with controllable packing density have been prepared on transparent conductive oxide substrates using a short, simple galvanic nucleation step. The packing density of the ZnO nanorods (NR) was increased by similar to 200% from 8.5 x 10(8) cm(-2) to 1.7 x 10(9) cm(-2) by increasing the initial galvanic nucleation (IGN...
Article
Full-text available
We demonstrate an effective recombination zone consisting of Mg:Ag (1:3) alloy and MoO 3 layers with 0.8 nm and 3 nm respectively for application in tandem organic photovoltaic devices based on zinc phthalocyanine (ZnPc) donor and fullerene C 60 acceptor. The Mg:Ag layer ensures an optimum electron selectivity, while MoO 3 layer effectively selects...
Article
Currently, Cu-containing chalcopyrite-based solar cells provide the highest conversion efficiencies among all thin-film photovoltaic (PV) technologies. They have reached efficiency values above 20%, the same performance level as multi-crystalline silicon-wafer technology that dominates the commercial PV market. Chalcopyrite thin-film heterostructur...
Conference Paper
Motivation - Feedstock materials account for a large fraction of PV device costs - Material costs depend on purity level (3N, 4N, 5N, 6N) - Using lower grade material can reduce device costs - Cost/Watt peak only reduced if efficiency is not reduced - Some elements favourable (Na, K, Sb, ...) others harmful (Fe, Ni, Cr, …) depending on concentratio...
Article
The lack of an efficiency increase with increasing Ga content in Cu(In,Ga)Se2 solar cells has attracted much scientific interest. It has been claimed that the physical properties of grain boundaries are responsible for this curious effect. Here, we present an in-depth analysis of electronic potential barriers at grain boundaries (GBs) in a series o...
Conference Paper
Cu 2 ZnSnS 4 thin films were grown by the spray pyrolysis method and annealed in an evacuated ampoule in presence of elemental sulfur. Annealing led to a significant decrease of the conductivity (by more than three orders of magnitude at room temperature). Transport properties are governed by the Mott variable-range hopping conduction mechanism in...
Conference Paper
Full-text available
Impurities in the absorber material of chalcopyrite (Cu(InxGa1-x)Se2) PV devices can have substantial influence on the device characteristics. Therefore a better understanding of the influence of impurities on the performance of CIGS solar cell is needed. Usually impurities are not from one single element, but rather a combination of different elem...
Conference Paper
ABSTRACT: CuZnSn(S,Se)4 (CZTSSe) with an optical band gap around 1.0-1.5 eV and absorption coefficient over 104 cm-1 is the optimal candidate for photovoltaic application. Although the conversion efficiencies of the best CZTSSe-based solar cells (12.6 % [1]) are still far below the Cu(In,Ga)Se2 (CIGS) based solar cells (21.7 % [2]) CZTSSe material...
Conference Paper
CuZnSn(S,Se)4 (CZTSSe) with an optical band gap around 1.0-1.5 eV and absorption coefficient over 10 4 cm -1 is the optimal candidate for photovoltaic application. Although the conversion efficiencies of the best CZTSSe-based solar cells (12.6 % [1]) are still far below the Cu(In,Ga)Se2 (CIGS) based solar cells (21.7 % [2]) CZTSSe material has been...
Conference Paper
Full-text available
Overall application of inexpensive, non-vacuum chemical (CBD) and electrochemical deposition (ECD) techniques that can be scaled-up to industrial processes is targeted for processing the absorber-, buffer-, and window-layer of CISe/CIGSe TFSCs to overcome current process incompatibilities mainly resulting from the simultaneous use of moderate tempe...
Article
Cu-poor and Cu-rich Cu(In,Ga)Se2 (CIGSe) absorbers were used as substrates for the chemical bath deposition of ultrathin CdS buffer layers in the thickness range of a few nanometres in order to make the CIGSe/CdS interface accessible by hard x-ray photo-emission spectroscopy. The composition of both, the absorber and the buffer layer as well as the...
Article
The implementation of potassium fluoride treatments as a doping and surface modification procedure in chalcopyrite absorber preparation has recently gained much interest since it led to new record efficiencies for this kind of solar cells. In the present work, Cu(In,Ga)Se2 absorbers have been evaporated on alkali containing Mo/soda-lime glass subst...
Conference Paper
Sputtering of Zn(O, S) has emerged as an alternative technology for establishing the pn-junction for Cd-free chalcopyrite-based solar cells. Compared to the chemical bath deposition of CdS, this technology promises dry in-line fabrication of Cd-free modules with reduced complexity and cost. We will review the milestones of its development from fund...
Article
The use of relatively low purity zinc nitrate for electrochemical deposition of compact ZnO films is attractive for large scale production because of the cost saving potential. ZnO films were grown on SnO2:F and magnetron sputtered ZnO:Al templates using a three electrode potentiostatic system in galvanic mode. The electrolyte consisted of a 0.1 M...
Article
ZnO nanorod arrays placed within the architecture of the Cu(In,Ga)Se2 solar cell present promising concepts to maximize photoconversion by optical and electrical enhancement. Three different Cu(In,Ga)Se2 solar cell architectures utilizing ZnO nanorods are introduced. New technological insights are given for electrodeposited ZnO nanorod anti-reflect...
Conference Paper
Development of new cell architectures and concepts is essential to increase the thin film solar cell performance to be competitive with other technologies. In this way, nanostructured materials like ZnO nanorod arrays (NRA) for higher efficiency devices have revealed to be a very promising alternative. Besides, it is well know that the development...
Patent
Die Erfindung betrifft eine Tandem-Dünnschicht-Solarzelle, die mindestens aus zwei Subzellen besteht, wobei das Absorbermaterial der rückseitigen Zelle anorganisch oder organisch ist und breitbandig absorbiert und das organische Absorbermaterial der Frontzelle in einem Bereich des Spektrums schmalbandig absorbiert, wobei dieser Bereich gegenüber de...
Patent
Die Erfindung betrifft eine Tandem-Dünnschicht-Solarzelle, die mindestens aus zwei Subzellen besteht, wobei das Absorbermaterial der rückseitigen Zelle anorganisch oder organisch ist und breitbandig absorbiert und das organische Absorbermaterial der Frontzelle in einem Bereich des Spektrums schmalbandig absorbiert, wobei dieser Bereich gegenüber de...
Article
Full-text available
We demonstrate hybrid solar cells with ZnO-nanorods (ZnO-NRs) prepared by a low temperature electrochemical method and small molecule organic absorber processed by dry organic vapor phase deposition. A homogeneous coverage of ZnO-NRs by the blend absorber consisting of zinc phthalocyanine (ZnPc) as donor and of fullerene C60 as acceptor is best rea...