A5048579376- Chalcogenide Semiconductor Thin Films
- Quantum Dots Synthesis And Properties
- Semiconductor materials and interfaces
- Copper-based nanomaterials and applications
- Silicon and Solar Cell Technologies
- Electronic and Structural Properties of Oxides
- Semiconductor materials and devices
- Catalytic Processes in Materials Science
- ZnO doping and properties
- Advancements in Solid Oxide Fuel Cells
- Reservoir Engineering and Simulation Methods
- Catalysis and Oxidation Reactions
- Geothermal Energy Systems and Applications
- Pressure Ulcer Prevention and Management
- Diabetic Foot Ulcer Assessment and Management
- Healthcare and Venom Research
- Advanced Memory and Neural Computing
- High-Temperature Coating Behaviors
- solar cell performance optimization
- Nuclear Materials and Properties
- Electrocatalysts for Energy Conversion
- Advanced Electron Microscopy Techniques and Applications
- Perovskite Materials and Applications
- Maternal and Perinatal Health Interventions
- Diagnosis and Treatment of Venous Diseases
San Joaquin Valley College
2021
Swiss Federal Laboratories for Materials Science and Technology
2012-2017
Flisom (Switzerland)
2016-2017
Desert Valley Hospital
2016
Valley Medical Center
2016
Santa Clara Valley Medical Center
2016
ETH Zurich
2011-2015
National Institute for Materials Science
2012
Kyushu University
2012
Thin film solar cells with a Cu(In,Ga)Se2 (CIGS) absorber layer achieved efficiencies above 20%. In order to achieve such high performance the of device has be doped alkaline material. One possibility incorporate material is post deposition treatment (PDT), where thin NaF and/or KF deposited onto completely grown CIGS layer. this paper we discuss effects PDT different elements (Na and K) on electronic properties cells. We demonstrate that whereas Na more effective in increasing hole...
Abstract This review summarizes the current status of Cu(In,Ga)(S,Se) 2 (CIGS) thin film solar cell technology with a focus on recent advancements and emerging concepts intended for higher efficiency novel applications. The developments trends research in laboratories industrial achievements communicated within last years are reviewed, major linked to alkali post deposition treatment composition grading CIGS, surface passivation, buffer, transparent contact layers emphasized. Encouraging...
The introduction of a KF postdeposition treatment (KF PDT) Cu(In,Ga)Se2 (CIGS) thin films has led to the achievement several consecutive new world record efficiencies up 21.7% for CIGS solar cell technology. beneficial effect PDT on photovoltaic parameters was observed by groups in spite differing growth methods layer. For evaporated at lower temperature alkali-free, flexible plastic substrates, add Na already successfully applied. However, with additional under comparable conditions,...
A promising way to enhance the efficiency of CIGS solar cells is by combining them with perovskite in tandem devices. However, so far, such devices had limited due challenges developing NIR-transparent top cells, which allow photons energy below band gap be transmitted bottom cell. Here, a process for fabrication presented, enables power conversion efficiencies up 12.1% combined an average sub-band transmission 71% wavelength between 800 and 1000 nm. The combination cell enabled device 19.5%...
Solar cells based on chalcopyrite Cu(In, Ga)Se <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (CIGS) absorber layers show the highest potential for low-cost solar electricity by yielding comparable efficiencies to polycrystalline Si wafer-based cells, while also offering inherent advantages of thin-film technology cost reduction. Highest efficiency 20.3% was recently achieved rigid glass substrate. Deposition CIGS films onto flexible...
Direct and inverse photoemission were used to study the impact of alkali fluoride postdeposition treatments on chemical electronic surface structure Cu(In,Ga)Se2 (CIGSe) thin films for high-efficiency flexible solar cells. We find a large band gap (EgSurf, up 2.52 eV) NaF/KF-postdeposition treated (PDT) absorber significantly increases compared CIGSe bulk EgSurf 1.61 eV found an with NaF only. Both valence maximum (VBM) conduction minimum shift away from Fermi level. Depth-dependent...
Concepts of localized contacts and junctions through surface passivation layers are already advantageously applied in Si wafer-based photovoltaic technologies. For Cu(In,Ga)Se2 thin film solar cells, such concepts generally not applied, especially at the heterojunction, because lack a simple method yielding features with required size distribution. Here, we show novel, innovative nanopatterning approach to form homogeneously distributed nanostructures (<30 nm) on faceted, rough...
A NaF/KF postdeposition treatment (PDT) has recently been employed to achieve new record efficiencies of Cu(In,Ga)Se2 (CIGSe) thin film solar cells. We have used a combination depth-dependent soft and hard X-ray photoelectron spectroscopy as well absorption emission gain detailed insight into the chemical structure CIGSe surface how it is changed by different PDTs. Alkali-free CIGSe, NaF-PDT NaF/KF-PDT absorbers grown low-temperature coevaporation interrogated. find that alkali-free surfaces...
Doping the Cu(In,Ga)Se2 (CIGS) absorber layer with alkaline metals is necessary to process high efficiency solar cells. When growth of CIGS cells performed on soda-lime glass (SLG), elements naturally diffuse from substrate into layer. On other hand, when grown free substrates, have be added another source. In past, Na was believed most important dopant elements, even though K also observed SLG. Recently, beneficial effect a post deposition treatment KF pointed out and enabled production...
Thin-film solar cells based on the chalcopyrite Cu(In,Ga)Se <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (CIGS) absorber material show high potential for further cost reduction in photovoltaics. Compared with polycrystalline silicon (p-Si) wafer technology, thin-film technology has inherent advantages due to lower energy and consumption during production but typically shown conversion efficiency. However, past two years, new...
Abstract Deposition of Cu(In,Ga)Se 2 (CIGS) thin film solar cells on metallic substrate is an attractive approach for development low cost modules. However, in such devices, special care has to be taken avoid diffusion impurities, as Fe, Ni, and Cr, from the into active layers. In this work, influence Ni Cr impurities electronic properties CIGS investigated detail. Impurities were introduced layer by during deposition process a or precursor below Mo electrical back contact. A high...
Highly efficient thin film solar cells based on co-evaporated Cu(In,Ga)Se2 (CIGS) absorbers are typically grown with a [Ga]/([Ga] + [In]) (GGI) gradient across the thickness and Cu-poor composition. Upon increasing Cu content towards CIGS stoichiometry, lower defect density is expected, which should lead to increased absorption in near-infrared (NIR), diffusion length carrier collection. Further, optimization of GGI grading expected increase NIR response. In this contribution [Cu]/([In]...
Solar cells based on chalcopyrite Cu(In, Ga)Se <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> (CIGS) absorber layers show the highest potential for low-cost solar electricity by yielding comparable efficiencies to polycrystalline Si wafer-based cells, while also offering inherent advantages of thin-film technology cost reduction.Highest efficiency 20.3% was recently achieved rigid glass substrate. Deposition CIGS films onto flexible...
Hydrogenated indium oxide (IOH) is implemented as transparent front contact in Cu(In,Ga)Se2 (CIGS) solar cells, leading to an open circuit voltage VOC enhanced by ∼20 mV compared reference devices with ZnO:Al (AZO) electrodes. This effect reproducible a wide range of sheet resistances corresponding various IOH thicknesses. We present the detailed electrical characterization glass/Mo/CIGS/CdS/intrinsic ZnO (i-ZnO)/transparent conductive (TCO) different IOH/AZO ratios TCO order identify...
Abstract Reduction of the absorber thickness combined with deposition on a flexible substrate is technically viable strategy to allow lower cost manufacturing Cu(In,Ga)Se 2 solar modules. Flexible plastic substrates, however, require low‐temperature process and appropriate control band gap grading for achieving high efficiencies. In this work, we developed cells polyimide films using evaporated absorbers 0.8–1.3 µm. The double Ga‐grading profile across was modified by varying maximum Cu...
Abstract This work presents a systematic study that evaluates the feasibility and reliability of local band gap measurements Cu(In,Ga)Se 2 thin films by valence electron energy-loss spectroscopy (VEELS). The compositional gradients across layer cause variations in energy, which are experimentally determined using monochromated scanning transmission microscope (STEM). results reveal expected variation therefore confirm VEELS. precision accuracy discussed based on analysis individual error...
Cu(In,Ga) Se2 (CIGS) thin film solar cells have demonstrated very high efficiencies, but still the role of nanoscale inhomogeneities in CIGS and their impact on cell performance are not yet clearly understood. Due to polycrystalline structure CIGS, grain boundaries common structural defects that also accompanied by compositional variations. In this work, we apply valence electron energy loss spectroscopy scanning transmission microscopy study local band gap at a boundary absorber layer....
Quantum efficiency measurements of state the art Cu(In,Ga)Se2 (CIGS) thin film solar cells reveal current losses in near infrared spectral region. These can be ascribed to inadequate optical absorption or poor collection photogenerated charge carriers. Insight on limiting mechanism is crucial for development more efficient devices. The electron beam induced measurement technique applied device cross-sections promises an experimental access depth resolved information about carrier...
In this work we show how 2D numerical simulations can be used to design and optimize front-side point contacts in surface-passivated CIGS cells. Detailed analysis of the combinations passivation thickness, contact size pitch help identifying solutions able boost performance otherwise surface-limited cells: efficiencies close those cells with ideal (i.e., trap-free) CdS/CIGS interface achieved by optimization features low nm range. The effect varying CdS doping densities on cell has also been...