3,680 research outputs found
A new class of electron acceptor for organic solar cells
No full textThe University of Warwick (UK) sponsored the research project 'A new class of electron acceptor for organic solar cells' for Professor Alessandro Troisi in the Department of Chemistry (ref GCHHF0508) and commissioned Prof. Antonella Ciccarese in the Dipartimento DiSTeBA on behalf of the Subcontractor Università del Salento (Lecce,Italy). The design of alternative electron acceptors able to mimic the properties of fullerene derivatives is the aim of the Project. In a recent paper, Liu and Troisi identified the special characteristics of fullerene-based acceptors that makes them so much better as electron acceptors than any other material with otherwise similar characteristics. The subcontracted research is focused on the synthesis and spectroscopic characterization of four lead compounds with a "designed" degeneracy of the LUMO levels, in order to mimic the properties of fullerenes and therefore substitute them in the development of alternative electron acceptors.This research relies on the collaboration of Prof. Luigino Troisi, Dr Catia Granito, Dr Gabriele Giancane and co-workers
Rapid Evaluation of Dynamic Electronic Disorder in Molecular Semiconductors
No full textOne of the key factors limiting the charge mobility of molecular semiconductors is the fluctuation of transfer integrals, also known as dynamic disorder. This is a manifestation of the nonlocal electron-phonon coupling, a property that is computationally expensive to evaluate and, so far, prevented the study of this property on large datasets of molecules. In this article, we describe a methodology for the fast evaluation of the dynamic electronic disorder for molecular semiconductors from their crystalline structure. The computation is accelerated by (i) the evaluation of the Cartesian gradient of transfer integral and (ii) the use of approximate phonons evaluated within the rigid body approximation. The quality of the approximations is checked against less-approximated alternatives. This method is used to study a range of molecular crystals, and some general trends on the behavior of the nonlocal electron-phonon coupling are discussed. A strategy to find the optimal relative position between interacting molecules is proposed
Simulation of organic mixed ionic and electronic conductors with a combined classical and quantum mechanical model
No full textOrganic materials that efficiently couple electronic and ionic charge transport (OMIEC) have been
recognized as essential in a wide range of technologies [1], from energy storage and generation [2] to
nanomedicine and healthcare [3], thanks to their ease of processing, flexibility, low cost, and because
they can be finely tuned, e.g. to ensure perfect integration with cellular tissues for nanomedicine or a light
weight for energy storage.
Theoretical predictions could represent a great help in developing new materials, tailored for any given
application. However, they face the fundamental obstacle that, in these systems, the excess charge is
very mobile, and the dynamics of the polymer chain cannot be accurately described with a model
including only fixed point charges. Ions and polymer are comparatively slower and a methodology to
capture the correlated motions of excess charge and ions is currently unavailable. Considering a
prototypical interface for an archetypal OMIEC (poly-thiophene with glycol side chains), we constructed a
scheme based on the combination of MD and QM/MM to evaluate the classical dynamics of polymer,
water and ions, while allowing the excess charge of the polymer chains to rearrange following the
external electrostatic potential [4]. We find that the location of the excess charge varies substantially
between chains. The excess charge changes across multiple timescales, as a result of fast structural
fluctuations and slow rearrangement of the polymeric chains. Our results indicate that such effects are
likely important to describe the phenomenology of OMIEC, and we are working on the introduction of
additional features in the model to enable the study of processes such as electrochemical doping
Simulation of organic mixed ionic and electronic conductors with a combined classical and quantum mechanical model.
No full textSimulation of organic mixed ionic and electronic conductors with a combined classical and quantum mechanical model
No full textSimulation of organic mixed ionic and electronic conductors with a combined classical and quantum mechanical model
No full text
Diagnostic and Therapeutic Advancements in the Field of Animal Reproduction
No full textReproductive physiology and breeding have fascinated scientist since ancient times, and it is not surprising that explorations in these fields are included among the oldest and most well-documented branches of veterinary medicine [...
Quantitative Prediction of the Electro-Mechanical Response in Organic Crystals
No full textOrganic semiconductors’ inherent flexibility makes them appealing for advanced applications such as wearable electronics, e-skins, or pressure sensors, and can even be used to enhance their intrinsic electronic properties. Unfortunately, these applications for organic materials are currently hindered by the lack of a quantitative understanding of the interplay between their electrical and mechanical properties. In this work, this gap is filled by presenting an accurate methodology able to predict quantitatively the effects of external deformation on the charge transport properties of any organic semiconductors. Three prototypical materials are investigated, showing that the experimental variation of charge carrier mobility with strain is fully reproduced, even in a wide range of deformations applied along different crystal axes. The results indicate that the intrinsic electro-mechanical response of the materials varies by orders of magnitude within the class of organic semiconductors, a difference rationalized observing that the mobility trend is primarily influenced by the transfer integrals’ variation, rather than by a modification of the crystal phonons. In light of its robustness, accuracy, and low computational cost, this protocol represents an ideal tool to quantify the electro-mechanical response in new organic compounds, thus establishing a reliable route for a full exploitation of strain engineering in advanced technologies
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