1,721,023 research outputs found
Device level modeling of intermediate band quantum dot solar cells
Full text linkAmong many material candidates for next-generation solar cells, quantum dots offer unique opportunities. Aiming to maximally harness their nanoscale bandgap engineering, in this work we outline a multiscale, multiphysics modeling approach for the device level simulation of quantum dot solar cells. Examples of experimental validation are discussed, emphasizing the potential of light trapping techniques towards the implementation of quantum dot based intermediate band solar cells
Efficient multiphysics modeling of thin-film solar cells with periodically textured surfaces
No full textModeling of type-II quantum dot intermediate band solar cells accounting for thermal and optical intersubband transitions
Full text linkNovel solar cell concepts relying on the use of
nanostructures requires ad hoc device modeling tools able to
cope with carrier transport and charge transfer mechanisms
involving the host bulk material and the quantum confined states.
In this work we apply such approach to study the implication
of intersubband competitive processes in type-II GaSb/GaAs
quantum dots on their application to intermediate band solar
cells
Perovskite-Si solar cell: A three-terminal heterojunction bipolar transistor architecture
Full text linkOver the past decade, perovskite materials have attracted great interest for terrestrial photovoltaic (PV) applications thanks to their cheapness and excellent optoelectronic properties such as tunable bandgap, high absorption coefficient, long carrier lifetime and diffusion length. Perovskites have excellent potential for the development of high efficiency and low cost silicon-based tandem solar cells. Several research studies have been performed about perovskite/silicon tandem solar cells obtaining good conversion efficiencies of about 26%. In this work, we propose a perovksite-silicon solar cell based on the three-terminal hetero-junction bipolar transistor (3T-HBJT) architecture that overcomes several constraints of the series connected double junction cell - i.e. current matching and the need of tunnel junctions or recombination layers - exploiting a simpler structure and achieving high efficiency. In order to evaluate its performance potential, we adopt the classical Hovel model extended to deal with the 3T-HBT structure, demonstrating efficiencies up to 28.6% for cells without antireflection coating
Spin-symmetrised structures and vibrational frequencies of iron-sulfur clusters
No full textCalculations of relaxed geometries of multi-centre transition metal compounds are routinely carried out using Broken Symmetry Density Functional Theory. The resulting low-spin open shell electronic state is described by one single Slater determinant and is affected by spin contamination. To alleviate this symmetry breaking, the Extended Broken Symmetry (EBS) approach can be applied to complexes with an arbitrary number of local high-spin metal ions. The actual symmetry is therefore reconstructed through minimization of an effective Hamiltonian leading to a relaxed geometry consistent with the magnetic couplings. In the present work we extend the approach already introduced by [Chu et al., J. Chem. Theory Comput., 2017, 13, 4675] to the calculation of vibrational frequencies. As prototypes we have considered the iron-sulfur clusters Fe2S2Cl42- and Fe4S4Cl4. We have compared the results obtained for different spin states (high spin, broken symmetry and extended broken symmetry) and by using different DFT functionals (B3LYP, OPBE, BP, M06 and B2PLYP) and a post-HF method (SCS-MP2). The data have shown that for specific vibrational modes the EBS technique produces shifts up to 40 cm-1 with respect to the routinely used Broken Symmetry approach, indicating that the use of a consistent spin-symmetrised state is a crucial ingredient for an accurate description of vibrational properties, as certified by the comparison with the experimental data for the Fe2S2Cl42- cluster. This journal i
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
New insights into chloromethyl-oxirane and chloromethyl-thiirane in liquid and solid phase from low-temperature infrared spectroscopy and ab initio modeling
Full text linkA detailed study of the conformational landscape of chloromethyl-oxirane and chloromethyl-thiirane is here reported. The equilibrium of the three different conformers of the two molecules was assessed, using a joint approach of experimental and theoretical methods. High quality infrared spectroscopy measurements of the liquid and of the crystalline phases were interpreted with the aid of ab initio Molecular Dynamics (AIMD) simulations, anharmonic frequencies and free energy calculations, obtaining a very good reproduction of the experimental data. The modulation of the conformational equilibrium upon the addition of polar and non-polar solvents was computationally evaluated and results found a confirmation in experimental measures
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