Suchergebnisse

This work provides a rapid overview for the current state of surface passivation layer schemes for thin film solar cells: From its fundamentals to solar cell applications, and their perspective. It provides an overview of important literature and prospect considerations based on simulations. ; European Research Council (ERC) under the European Union [715027]

For silicon surface passivation, we investigate stack layers consisting of a thin Al₂O₃ layer and a TiO₂capping layer deposited by means of thermal atomic layer deposition (ALD). In this work, we studied the influence of different thermal post-deposition treatments and film thickness for the activation of passivating ALD Al₂O₃ single layers and Al₂O₃/TiO₂ stack layers. Our experiments show a substantial improvement of the passivation for the Al₂O₃/TiO₂ stack layers compared to a thin single Al₂O₃ layer. For the stacks, especially with less than 10 nm Al₂O₃, a TiO₂capping layer results in a remarkably lower surface recombination. Effective fixed charge density of Al₂O₃/TiO₂ stack layers increases after TiO₂deposition and O₂ annealing. It is also demonstrated that the enhanced surface passivation can be mainly related to a remarkably low interface defect density of 1.1 × 10¹⁰ eV¯¹ cm¯², whereas post-TiO₂ heat treatment in O₂ ambience is not beneficial for the passivation of silicon, which is attributed to increasing interface defect density of stack layers. ; This project has been supported by the Australian Government through the Australian Solar Institute, part of the Clean Energy Initiative.

For silicon surface passivation, we investigate stack layers consisting of a thin Al₂O₃ layer and a TiO₂capping layer deposited by means of thermal atomic layer deposition (ALD). In this work, we studied the influence of different thermal post-deposition treatments and film thickness for the activation of passivating ALD Al₂O₃ single layers and Al₂O₃/TiO₂ stack layers. Our experiments show a substantial improvement of the passivation for the Al₂O₃/TiO₂ stack layers compared to a thin single Al₂O₃ layer. For the stacks, especially with less than 10 nm Al₂O₃, a TiO₂capping layer results in a remarkably lower surface recombination. Effective fixed charge density of Al₂O₃/TiO₂ stack layers increases after TiO₂deposition and O₂ annealing. It is also demonstrated that the enhanced surface passivation can be mainly related to a remarkably low interface defect density of 1.1 × 10¹⁰ eV¯¹ cm¯², whereas post-TiO₂ heat treatment in O₂ ambience is not beneficial for the passivation of silicon, which is attributed to increasing interface defect density of stack layers. ; This project has been supported by the Australian Government through the Australian Solar Institute, part of the Clean Energy Initiative.

The long-term (>18 months) protection of Ni surfaces against oxidation under atmospheric conditions is demonstrated by coverage with single-layer graphene, formed by chemical vapor deposition. In situ, depth-resolved X-ray photoelectron spectroscopy of various graphene-coated transition metals reveals that a strong graphene-metal interaction is of key importance in achieving this long-term protection. This strong interaction prevents the rapid intercalation of oxidizing species at the graphene-metal interface and thus suppresses oxidation of the substrate surface. Furthermore, the ability of the substrate to locally form a passivating oxide close to defects or damaged regions in the graphene overlayer is critical in plugging these defects and preventing oxidation from proceeding through the bulk of the substrate. We thus provide a clear rationale for understanding the extent to which two-dimensional materials can protect different substrates and highlight the key implications for applications of these materials as barrier layers to prevent oxidation. ; RSW acknowledges a Research Fellowship from St. John's College, Cambridge and a Marie Skłodowska-Curie Individual Fellowship (Global) under grant ARTIST (no. 656870) from the European Union's Horizon 2020 research and innovation programme. LD and SC acknowledge EPSRC Doctoral Training Awards and AC-V acknowledges a Conacyt Cambridge Scholarship and the Roberto Rocca Fellowship. S.H. acknowledges funding from ERC grant InsituNANO (no. 279342). This research was partially supported by the EUFP7 Work Programme under grant GRAFOL (project reference 285275), and EPSRC under grant GRAPHTED (project reference EP/K016636/1). ; This is the final version of the article. It was first available from ACS via http://dx.doi.org/10.1021/jacs.5b08729

As for other multivalent systems, the interface between the calcium (Ca) metal anode and the electrolyte is of paramount importance for reversible plating/stripping. Here, we combined experimental and theoretical approaches to unveil the potential solid electrolyte interphase (SEI) components enabling facile Ca plating. Borates compounds, in the form of cross-linked polymers are suggested as divalent conducting component. A pre-passivation protocol with such SEI is demonstrated and allows to broaden the possibility for electrolyte formulation. We also demonstrated a 10-fold increase in Ca plating kinetics by tuning the cation solvation structure in the electrolyte limiting the degree of contact ion pair. ; Funding from the European Union's Horizon 2020 research and innovation program H2020 is acknowledged: European Research Council (ERC-2016-STG, CAMBAT grant agreement no. 715087) and H2020-MSCA-COFUND-2016 (DOC-FAM, grant agreement no. 754397). A. Ponrouch is grateful to the Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496) and to Prof. D. Lemordant (Tours University, France) for stimulating discussions. P. Canepa acknowledges funding from the National Research Foundation under his NRFF NRFF12-2020-0012 and the ANR-NRF NRF2019-NRF-ANR073 Na-MASTER. P. Canepa acknowledges the National Supercomputing Centre, Singapore (https://www.nscc.sg). This work has been done in the frame of the Doctoral Degree Program in Materials Science by the Universitat Autònoma de Barcelona. The FTIR experiments were performed at MIRAS beamline at ALBA Synchrotron with the collaboration of ALBA staff. ; Peer reviewed

In this work, metal-insulator-semiconductor structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al2O3), silicon nitride, and silicon oxide (SiOx) to be used as passivation layers in Cu(In,Ga)Se-2 (CIGS) thin-film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance versus conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q(f)). The density of interface defects (D-it) was estimated from capacitance versus conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 degrees C) and the use of a sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiOx deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower Dit values was Al2O3 when deposited by sputtering. ; This work was supported by European Union's Horizon 2020 research and innovation programme ARCIGS-M project under Grant 720887. The work of J. M. V. Cunha and P. M. P. Salome was supported by the Fundacao para a Ciencia e a Tecnologia (FCT) through the project IF/00133/2015. The work of J. P. Teixeira and J. P. Leitao was supported by the FCT through the project UID/CTM/50025/2013. The work of B. Vermang was supported by the European Research Council under the European Union's Horizon 2020 research and innovation programme under Grant 715027.