scholarly journals Revisiting the Charge-Transfer States at Pentacene/C60 Interfaces with the GW/Bethe–Salpeter Equation Approach

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2728
Author(s):  
Takatoshi Fujita ◽  
Yoshifumi Noguchi ◽  
Takeo Hoshi
Keyword(s):  
Charge Transfer ◽  
Energy Levels ◽  
Absorption Peak ◽  
Model Systems ◽  
Equation Approach ◽  
Charge Delocalization ◽  
The Face ◽  
Donor Acceptor ◽  
The Impact ◽  
Main Absorption Peak

Molecular orientations and interfacial morphologies have critical effects on the electronic states of donor/acceptor interfaces and thus on the performance of organic photovoltaic devices. In this study, we explore the energy levels and charge-transfer states at the organic donor/acceptor interfaces on the basis of the fragment-based GW and Bethe–Salpeter equation approach. The face-on and edge-on orientations of pentacene/C60 bilayer heterojunctions have employed as model systems. GW+Bethe–Salpeter equation calculations were performed for the local interface structures in the face-on and edge-on bilayer heterojunctions, which contain approximately 2000 atoms. Calculated energy levels and charge-transfer state absorption spectra are in reasonable agreements with those obtained from experimental measurements. We found that the dependence of the energy levels on interfacial morphology is predominantly determined by the electrostatic contribution of polarization energy, while the effects of induction contribution in the edge-on interface are similar to those in the face-on. Moreover, the delocalized charge-transfer states contribute to the main absorption peak in the edge-on interface, while the face-on interface features relatively localized charge-transfer states in the main absorption peak. The impact of the interfacial morphologies on the polarization and charge delocalization effects is analyzed in detail.

Synthesis of a new W-type of functional polymer for improving intermolecular charge transfer processes at donor/acceptor interfaces

2019 ◽  
Vol 31 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Yun-Fan Zhang ◽  
Fawen Wu
Keyword(s):  
Charge Transfer ◽  
Energy Gap ◽  
Energy Levels ◽  
Coupling Reaction ◽  
Photocurrent Density ◽  
Orbital Energy ◽  
Functional Polymer ◽  
Suzuki Coupling Reaction ◽  
Donor Acceptor ◽  
Lowest Unoccupied Molecular Orbital

Optimizing charge transfer (CT) processes at donor/acceptor interfaces is an important subject to improving photocurrent density. Geometries of functional polymers play important roles in design of new types of polymers, which were used as electron donor to improve effective separation of electron-hole pairs at donor/acceptor interfaces. In this article, a novel W-type of polymer, poly(1-[4-(9-(2-ethylhexyl)carbazole-3-yl)]phenylazo-2-phenylazoacenaphthylene), was synthesized by a Suzuki coupling reaction for improving interaction between polymers and electron acceptors to enhance intermolecular CT. Geometry of combination of the polymer and C60 shows that main-chain of the polymer could sufficiently touch C60 derivatives. The polymer exhibited a broadband light absorption at the wavelength range from 250 to 650 nm. Ultraviolet–visible spectra and cyclic voltammetry curve suggest that the highest occupied, lowest unoccupied molecular orbital energy levels, and energy gap values are −5.09, −3.18 and 1.91 eV. Fluorescence quenching experiments shows that 99.9% of emission fluorescence of the polymer was quenched by added C60. Therefore, excited electrons at the polymer would be completely transferred to C60 molecules. This article suggests a new W-type functional polymer for improving intermolecular CT processes at donor/acceptor interfaces.

A Method for Assessing the Overall Impact Performance of Riot Helmets

2003 ◽  
Vol 19 (3) ◽  
pp. 246-254 ◽  
Author(s):  
Jean-Philippe Dionne ◽  
Ismail El Maach ◽  
Ahmed Shalabi ◽  
Aris Makris
Keyword(s):  
Comparative Study ◽  
Impact Energy ◽  
Energy Levels ◽  
Performance Impact ◽  
Impact Performance ◽  
Frontal Impacts ◽  
National Institute Of Justice ◽  
Crowd Control ◽  
The Face ◽  
The Impact

The objective of the present paper is to investigate the overall impact performance of various riot helmets in a comparative study. The National Institute of Justice (NIJ-0104.02) and the Canadian Standards Association (CSA-Z611-02) standards regulate the use of riot helmets in North America. Both sets of standards have a number of requirements for impact performance. Impact tests carried out with the use of a drop tower apparatus compliant with NIJ test protocols demonstrated large differences in impact attenuation level among the helmets from six manufacturers in terms of frontal and lateral impacts to the shell, and face-shield deflection. For instance, the impact energy yielding a head form acceleration of 300 g’s was measured for each helmet for frontal impacts on the helmet shell. Values ranging from 69 J up to 171 J were obtained. The energy levels of typical crowd-control threats, e.g., baton blows and projectiles, were quantified and compared with the impact energy values used in the standards. It is observed that the NIJ face-shield deflection requirement is low as compared to actual riot threats, whereas the CSA requirements are more in line with these threats. A novel method was devised to objectively assign a global impact performance score to each helmet. This method takes into account the frontal and lateral impacts to the shell as well as the face-shield deflection tests. It is based on the directional origin of the threat and the geometry of the helmets (frontal percentage area of the visor). From these global performance scores, it is possible to obtain a ranking of the various riot helmets used in the present comparative study. Based on the analysis of the global scores, it was found that appropriate protection of the face (through an impact resistant visor) is the key feature for a helmet that will be used in riot environments.

scholarly journals The Impact of Local Morphology on Organic Donor/Acceptor Charge Transfer States

2018 ◽  
Vol 8 (28) ◽  
pp. 1702816 ◽  
Author(s):  
YunHui L. Lin ◽  
Michael A. Fusella ◽  
Barry P. Rand
Keyword(s):  
Charge Transfer ◽  
Donor Acceptor ◽  
The Impact

scholarly journals Optical, Electrochemical, Thermal, and Structural Properties of Synthesized Fluorene/Dibenzosilole-Benzothiadiazole Dicarboxylic Imide Alternating Organic Copolymers for Photovoltaic Applications

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1147 ◽  
Author(s):  
Ary R. Murad ◽  
A. Iraqi ◽  
Shujahadeen B. Aziz ◽  
Sozan N. Abdullah ◽  
Rebar T. Abdulwahid ◽  
...  
Keyword(s):  
Structural Properties ◽  
Energy Levels ◽  
Average Molecular Weight ◽  
Excellent Thermal Stability ◽  
Alkyl Chains ◽  
Molecular Weights ◽  
Photovoltaic Applications ◽  
Amorphous Nature ◽  
Donor Acceptor ◽  
The Impact

In this work, four donor–acceptor copolymers, PFDTBTDI-DMO, PFDTBTDI-8, PDBSDTBTDI-DMO, and PDBSDTBTDI-8, based on alternating 2,7-fluorene or 2,7-dibenzosilole flanked by thienyl units, as electron-donor moieties and benzothiadiazole dicarboxylic imide (BTDI) as electron-accepting units, have been designed and synthesized for photovoltaic applications. All polymers were synthesized in good yields via Suzuki polymerization. The impact of attaching two different alkyl chains (3,7-dimethyloctyl vs. n-octyl) to the BTDI units upon the solubilities, molecular weights, optical and electrochemical properties, and thermal and structural properties of the resulting polymers was investigated. PFDTBTDI-8 has the highest number average molecular weight (Mn = 24,900 g·mol−1) among all polymers prepared. Dibenzosilole-based polymers have slightly lower optical band gaps relative to their fluorene-based analogues. All polymers displayed deep-lying HOMO levels. Their HOMO energy levels are unaffected by the nature of either the alkyl substituents or the donor moieties. Similarly, the LUMO levels are almost identical for all polymers. All polymers exhibit excellent thermal stability with Td exceeding 350 °C. X-ray powder diffraction (XRD) studies have shown that all polymers have an amorphous nature in the solid state.

scholarly journals Effect of Electronic Acceptor Segments on Photophysical Properties of Low-Band-Gap Ambipolar Polymers

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Yuanzuo Li ◽  
Jingang Cui ◽  
Jianing Zhao ◽  
Jinglin Liu ◽  
Peng Song ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Photophysical Properties ◽  
Energy Levels ◽  
Quantum Chemistry Calculation ◽  
Difference Density ◽  
Charge Difference Density ◽  
Chemistry Calculation ◽  
Donor Acceptor ◽  
The Relationship

Stimulated by a recent experimental report, charge transfer and photophysical properties of donor-acceptor ambipolar polymer were studied with the quantum chemistry calculation and the developed 3D charge difference density method. The effects of electronic acceptor strength on the structure, energy levels, electron density distribution, ionization potentials, and electron affinities were also obtained to estimate the transporting ability of hole and electron. With the developed 3D charge difference density, one visualizes the charge transfer process, distinguishes the role of molecular units, and finds the relationship between the role of DPP and excitation energy for the three polymers during photo-excitation.

Impact resistance of Z-pin-reinforced sandwich composites

2019 ◽  
Vol 53 (26-27) ◽  
pp. 3681-3699 ◽  
Author(s):  
Gaye Kaya ◽  
Erdem Selver
Keyword(s):  
Distribution Density ◽  
Impact Test ◽  
Sheet Material ◽  
Energy Levels ◽  
Impact Resistance ◽  
Great Influence ◽  
Sandwich Composites ◽  
The Face ◽  
The Impact ◽  
Core Part

This study investigates the effect of face materials, Z-pin types and distribution densities on drop-weight impact properties of foam core sandwich composites. The novelty of this study is to eliminate damage of face part by only reinforcing the core part of sandwich structures. Impact test was performed at different energy levels (20–50 J). The addition of Z-pins into the sandwich composites decreased the elasticity and ductility while it increased the stiffness of sandwich composites. The Z-pin reinforcement increased the peak forces, but decreased the peak deformations of the sandwich composites. However, higher energy absorption was only observed at the higher Z-pin distribution density. The results showed that Z-pin distribution density, bonding between the face sheets/pins, and the face sheet material have a great influence on the impact behaviour of the Z-pin-reinforced sandwich composites besides the Z-pin types.

scholarly journals Resolving Donor-Acceptor Interfaces and Charge Carrier Energy Levels of Organic Semiconductors with Polar Side Chains

2020 ◽  
Author(s):  
Riccardo Alessandri ◽  
Selim Sami ◽  
Jonathan Barnoud ◽  
Alex H. de Vries ◽  
Siewert-Jan Marrink ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Organic Semiconductors ◽  
Large Scale ◽  
Energy Levels ◽  
Acid Methyl Ester ◽  
Side Chains ◽  
Organic Thin Film ◽  
Carrier Energy ◽  
Donor Acceptor ◽  
The Impact

<div> <div> <div> <p>Organic semiconductors consisting of molecules bearing polar side chains have been proposed as potential candidates to overcome the limitations of organic photovoltaics owing to their enhanced dielectric constant. However, introducing such polar molecules in photovoltaic devices has not yet resulted in higher efficiencies. A microscopic understanding of the impact of polar side chains on electronic and structural properties of organic semiconductors is paramount to rationalize their effect. Here, we investigate the impact of such side chains on bulk heterojunction overall morphology, molecular configurations at donor-acceptor (DA) interfaces, and charge carrier energy levels. The multiscale modeling approach used allows to resolve DA interfaces with atomistic resolution while taking into account the large-scale self-organization process which takes place during the processing of an organic thin film. The polar fullerene-based blends are compared to the well-studied reference system, poly(3-hexyl-thiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM). Introduction of polar side chains on a similar molecular scaffold does not affect molecular orientations at the DA interfaces; such orientations are however found to be affected by processing conditions and polymer molecular weight. Polar side chains, instead, are found to impact considerably the charge carrier energy levels of the organic blend, causing electrostatic-induced broadening of these levels. </p> </div> </div> </div>

scholarly journals The impact of the lung environment on macrophage development, activation and function: diversity in the face of adversity

2022 ◽  
Author(s):  
Calum C. Bain ◽  
Andrew S. MacDonald
Keyword(s):  
New Technologies ◽  
Model Systems ◽  
Lung Macrophage ◽  
Renaissance Period ◽  
Recent Developments ◽  
The Face ◽  
Health And Disease ◽  
And Function ◽  
The Impact ◽  
Novel Model

AbstractThe last decade has been somewhat of a renaissance period for the field of macrophage biology. This renewed interest, combined with the advent of new technologies and development of novel model systems to assess different facets of macrophage biology, has led to major advances in our understanding of the diverse roles macrophages play in health, inflammation, infection and repair, and the dominance of tissue environments in influencing all of these areas. Here, we discuss recent developments in our understanding of lung macrophage heterogeneity, ontogeny, metabolism and function in the context of health and disease, and highlight core conceptual advances and key unanswered questions that we believe should be focus of work in the coming years.

scholarly journals A molecular roadmap towards organic donor-acceptor complexes with high-performance thermoelectric response

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wen Shi ◽  
Tianqi Deng ◽  
Zicong Marvin Wong ◽  
Gang Wu ◽  
Shuo-Wang Yang
Keyword(s):  
Charge Transfer ◽  
Molecular Orbital ◽  
High Performance ◽  
Molecular Design ◽  
Electronic Materials ◽  
Energy Levels ◽  
Transport Processes ◽  
Chemical Structures ◽  
Donor And Acceptor ◽  
Donor Acceptor

AbstractAs a unique class of molecular electronic materials, organic donor–acceptor complexes now exhibit tantalizing prospect for heat–electricity interconversion. Over the past decades, in design of these materials for thermoelectric applications, consistent efforts have been made to synthesize a wide variety of structures and to characterize their properties. However, hitherto, one of the paramount conundrums, namely lack of systematic molecular design principles, has not been addressed yet. Here, based on ab initio calculations, and by comprehensively examining the underlying correlation among thermoelectric power factors, non-intuitive transport processes, and fundamental chemical structures for 13 prototypical organic donor–acceptor complexes, we establish a unified roadmap for rational development of these materials with increased thermoelectric response. We corroborate that the energy levels of frontier molecular orbitals in the isolated donor and acceptor molecules control the charge transfer, electronic property, charge transport, and thermoelectric performance in the solid-state complexes. Our results demonstrate that tailoring a suitable energy-level difference between donor’s highest occupied molecular orbital and acceptor’s lowest unoccupied molecular orbital holds the key to achieving an outstanding power factor. Moreover, we reveal that the charge-transfer-caused Coulomb scattering governs the charge and thermoelectric transport in organic donor–acceptor complexes.

scholarly journals Resolving Donor-Acceptor Interfaces and Charge Carrier Energy Levels of Organic Semiconductors with Polar Side Chains

2020 ◽  
Author(s):  
Riccardo Alessandri ◽  
Selim Sami ◽  
Jonathan Barnoud ◽  
Alex H. de Vries ◽  
Siewert-Jan Marrink ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Organic Semiconductors ◽  
Large Scale ◽  
Energy Levels ◽  
Acid Methyl Ester ◽  
Side Chains ◽  
Organic Thin Film ◽  
Carrier Energy ◽  
Donor Acceptor ◽  
The Impact

<div> <div> <div> <p>Organic semiconductors consisting of molecules bearing polar side chains have been proposed as potential candidates to overcome the limitations of organic photovoltaics owing to their enhanced dielectric constant. However, introducing such polar molecules in photovoltaic devices has not yet resulted in higher efficiencies. A microscopic understanding of the impact of polar side chains on electronic and structural properties of organic semiconductors is paramount to rationalize their effect. Here, we investigate the impact of such side chains on bulk heterojunction overall morphology, molecular configurations at donor-acceptor (DA) interfaces, and charge carrier energy levels. The multiscale modeling approach used allows to resolve DA interfaces with atomistic resolution while taking into account the large-scale self-organization process which takes place during the processing of an organic thin film. The polar fullerene-based blends are compared to the well-studied reference system, poly(3-hexyl-thiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM). Introduction of polar side chains on a similar molecular scaffold does not affect molecular orientations at the DA interfaces; such orientations are however found to be affected by processing conditions and polymer molecular weight. Polar side chains, instead, are found to impact considerably the charge carrier energy levels of the organic blend, causing electrostatic-induced broadening of these levels. </p> </div> </div> </div>

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