Publications by authors named "Hossein Mirhosseini"

6 Publications

  • Page 1 of 1

investigation of Cu(In,Ga)Se-based solar cells.

Phys Chem Chem Phys 2020 Dec;22(46):26682-26701

Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany.

Photovoltaics is one of the most promising and fastest-growing renewable energy technologies. Although the price-performance ratio of solar cells has improved significantly over recent years, further systematic investigations are needed to achieve higher performance and lower cost for future solar cells. In conjunction with experiments, computer simulations are powerful tools to investigate the thermodynamics and kinetics of solar cells. Over the last few years, we have developed and employed advanced computational techniques to gain a better understanding of solar cells based on copper indium gallium selenide (Cu(In,Ga)Se2). Furthermore, we have utilized state-of-the-art data-driven science and machine learning for the development of photovoltaic materials. In this Perspective, we review our results along with a survey of the field.
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http://dx.doi.org/10.1039/d0cp04712kDOI Listing
December 2020

A High-Rate Two-Dimensional Polyarylimide Covalent Organic Framework Anode for Aqueous Zn-Ion Energy Storage Devices.

J Am Chem Soc 2020 Nov 9;142(46):19570-19578. Epub 2020 Nov 9.

Center for Advancing Electronics Dresden (cfaed) & Faculty of Chemistry and Food Chemistry, Technische Universität Dresden, 01062 Dresden, Germany.

Rechargeable aqueous Zn-ion energy storage devices are promising candidates for next-generation energy storage technologies. However, the lack of highly reversible Zn-storage anode materials with low potential windows remains a primary concern. Here, we report a two-dimensional polyarylimide covalent organic framework (PI-COF) anode with high-kinetics Zn-storage capability. The well-organized pore channels of PI-COF allow the high accessibility of the build-in redox-active carbonyl groups and efficient ion diffusion with a low energy barrier. The constructed PI-COF anode exhibits a specific capacity (332 C g or 92 mAh g at 0.7 A g), a high rate capability (79.8% at 7 A g), and a long cycle life (85% over 4000 cycles). Raman investigation and first-principle calculations clarify the two-step Zn-storage mechanism, in which imide carbonyl groups reversibly form negatively charged enolates. Dendrite-free full Zn-ion devices are fabricated by coupling PI-COF anodes with MnO cathodes, delivering excellent energy densities (23.9 ∼ 66.5 Wh kg) and supercapacitor-level power densities (133 ∼ 4782 W kg). This study demonstrates the feasibility of covalent organic framework as Zn-storage anodes and shows a promising prospect for constructing reliable aqueous energy storage devices.
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http://dx.doi.org/10.1021/jacs.0c07992DOI Listing
November 2020

Vibrational dynamics in lead halide hybrid perovskites investigated by Raman spectroscopy.

Phys Chem Chem Phys 2020 Mar;22(10):5604-5614

Institute of Solid State Physics, Technische Universitat Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.

Lead halide perovskite semiconductors providing record efficiencies of solar cells have usually mixed compositions doped in A- and X-sites to enhance the phase stability. The cubic form of formamidinium (FA) lead iodide reveals excellent opto-electronic properties but transforms at room temperature (RT) into a hexagonal structure which does not effectively absorb visible light. This metastable form and the mechanism of its stabilization by Cs+ and Br- incorporation are poorly characterized and insufficiently understood. We report here the vibrational properties of cubic FAPbI3 investigated by DFT calculations on phonon frequencies and intensities, and micro-Raman spectroscopy. The effects of Cs+ and Br- partial substitution are discussed. We support our results with the study of FAPbBr3 which expands the identification of vibrational modes to the previously unpublished low frequency region (<500 cm-1). Our results show that the incorporation of Cs+ and Br- leads to the coupling of the displacement of the A-site components and weakens the bonds between FA+ and the PbX6 octahedra. We suggest that the enhancement of α-FAPbI3 stability can be a product of the release of tensile stresses in the Pb-X bond, which is reflected in a red-shift of the low frequency region of the Raman spectrum (<200 cm-1).
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http://dx.doi.org/10.1039/c9cp06568gDOI Listing
March 2020

Diffusion of Alkali Metals in Polycrystalline CuInSe and Their Role in the Passivation of Grain Boundaries.

ACS Appl Mater Interfaces 2019 Apr 9;11(16):14821-14829. Epub 2019 Apr 9.

Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany.

The behavior of alkali atom point defects in polycrystalline CuInSe is studied. In this work, three grain boundary models, one coherent twin boundary and two twin boundaries with dislocation cores, are considered. Total energy calculations show that all alkali metals tend to segregate at the grain boundaries. In addition, the segregation of alkali atoms is more pronounced at the grain boundaries with the dislocation cores. The diffusion of alkali metals along and near grain boundaries is studied as well. The results show that the diffusion of alkali atoms in the grain boundary models is faster than within the bulk. In addition, the ion exchange between Na and Rb atoms at the grain boundaries leads to the Rb enrichment at the grain boundaries and the increase of the Na concentration in the bulk. While the effects of Na and Rb point defects on the electronic structure of the grain boundary with the anion-core dislocation are similar, Rb atoms passivate the grain boundary with the cation-core dislocation more effectively than Na. This can explain the further improvement of the solar cell performance after the RbF-postdeposition treatment.
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http://dx.doi.org/10.1021/acsami.9b02158DOI Listing
April 2019

Interference of spin states in photoemission from Sb/Ag(111) surface alloys.

J Phys Condens Matter 2011 Feb 3;23(7):072207. Epub 2011 Feb 3.

Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.

Using a three-dimensional spin polarimeter we have gathered evidence for the interference of spin states in photoemission from the surface alloy Sb/Ag(111). This system features a small Rashba-type spin splitting of a size comparable to the momentum broadening of the quasiparticles, thus causing an intrinsic overlap between states with orthogonal spinors. Besides a small spin polarization caused by the spin splitting, we observe a large spin polarization component in the plane normal to the quantization axis of the Rashba effect. Strongly suggestive of coherent spin rotation, this effect is largely independent of the photon energy and photon polarization.
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http://dx.doi.org/10.1088/0953-8984/23/7/072207DOI Listing
February 2011

Tunable spin gaps in a quantum-confined geometry.

Phys Rev Lett 2008 Nov 7;101(19):196805. Epub 2008 Nov 7.

Laboratoire de Spectroscopie Electronique, Institut de Physique des Nanostructures, Ecole Polytechnique Fédérale de Lausanne (EPFL), station 3, CH-1015 Lausanne-Switzerland.

We have studied the interplay of a giant spin-orbit splitting and of quantum confinement in artificial Bi-Ag-Si trilayer structures. Angle-resolved photoelectron spectroscopy reveals the formation of a complex spin-dependent gap structure, which can be tuned by varying the thickness of the Ag buffer layer. This provides a means to tailor the electronic structure at the Fermi energy, with potential applications for silicon-compatible spintronic devices.
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http://dx.doi.org/10.1103/PhysRevLett.101.196805DOI Listing
November 2008