Mechanism of charge transport in organic semiconductors and carbon nanomaterials

2015 ◽  
Vol 1733 ◽  
Author(s):  
Yuqian Jiang ◽  
Jinyang Xi ◽  
Zhigang Shuai
Keyword(s):  
Charge Transport ◽  
Organic Semiconductors ◽  
Carbon Nanomaterials ◽  
Quantum Effect ◽  
Reorganization Energy ◽  
Tunneling Effect ◽  
Interaction Matrix ◽  
Electron Phonon Interaction ◽  
Wide Range ◽  
Nuclear Tunneling

ABSTRACTWe develop theoretical descriptions for charge transport in organic semiconductors and carbon nanomaterials. For the localized charges, we found the quantum nuclear tunneling effect is essential which could manifest isotope effect for mobility as well as exotic optical feature. Because the nuclear tunneling tends to favor electron transfer while heavier nuclei decrease the quantum effect, isotopic substitution should reduce carrier mobility. Moreover, the isotopic effect only occurs when the substituted nuclei contribute actively to vibrations with appreciable charge reorganization energy and coupling with carrier motion. For the band-like transport, we propose a Wannier extrapolation scheme for computing the electron-phonon interaction matrix for the Boltzmann equation. Our calculation indicates that the intrinsic electron-phonon scatterings in two-dimensional carbon materials are dominated by low-energy longitudinal-acoustic phonon scatterings over a wide range of temperatures, while by high-frequency optical phonons at high temperature. The electron mobilities of α- and γ-graphynes are predicted to be ca.104 cm2V-1s-1 at room temperature.

Theoretical design of benzo[1,2-b:3,4-b′:5,6-b′′]tristhianaphthene and its derivatives as high performance organic semiconductors

2015 ◽  
Vol 14 (07) ◽  
pp. 1550058 ◽  
Author(s):  
Jun Yin ◽  
Kadali Chaitanya ◽  
Xue-Hai Ju
Keyword(s):  
Charge Carrier ◽  
Charge Transport ◽  
Transport Properties ◽  
Organic Semiconductors ◽  
High Performance ◽  
Reorganization Energy ◽  
Molecular Structures ◽  
Geometrical Structures ◽  
Subtle Change ◽  
Cyano Groups

In order to probe the effects of substituents (F and CN) attached to benzo[1,2-b:3,4-[Formula: see text]:5,6-[Formula: see text]]tristhianaphthene (BTTP) on their charge carrier transport properties, we investigated the characteristics of molecular structures and charge transport properties of BTTP and its derivatives (BTTP1, BTTP2, BTTP3, BTTP4, and BTTP5). Six crystal structures were predicted by the Monte Carlo-simulated annealing method with the embedded electrostatic potential charges method. Even a subtle change of geometrical structures may result in a great change of the reorganization energy. With increasing numbers of substituted fluorine atoms, the reorganization energy of the BTTP derivative increases, which is disadvantageous to the electron transport. In contrast, the attachment of the electron-withdrawing cyano groups to BTTP decreases the reorganization energy and raises the electron affinity, which is beneficial to electron injection and charge carrier stabilization. The introduction of cyano groups also results in an enhancement of [Formula: see text]–[Formula: see text] interaction and leads to an increase in the transfer integrals. Among the six compounds, the novel compound BTTP4 has the largest electron mobility (1.154[Formula: see text]cm[Formula: see text]) on account of its larger transfer integral and smaller reorganization energy, indicating that BTTP4 is a promising high-performance n-type organic semiconductor and worth to synthesize. The analysis of angular-resolution anisotropic mobilities for the BTTP and BTTP4 shows that it is helpful to control the orientations of the conducting channels for a better charge transport efficiency. This work provides a rational strategy for the design of high-performance n-type organic semiconductors from molecule to crystal structure.

Theoretical study on the charge transport in single crystals of TCNQ, F2-TCNQ and F4-TCNQ

2018 ◽  
Vol 20 (5) ◽  
pp. 3784-3794 ◽  
Author(s):  
Li-Fei Ji ◽  
Jian-Xun Fan ◽  
Shou-Feng Zhang ◽  
Ai-Min Ren
Keyword(s):  
Electron Transport ◽  
Charge Transport ◽  
Transport Properties ◽  
Single Crystals ◽  
Theoretical Study ◽  
Close Packing ◽  
Tunneling Effect ◽  
The Poor ◽  
Thermal Disorder ◽  
Nuclear Tunneling

The outstanding electron transport behavior of F2-TCNQ arises from its 3D close-packing motif and the nuclear tunneling effect; meanwhile, the poor transport properties of TCNQ and F4-TCNQ stem from their poor packing and strong thermal disorder.

scholarly journals Machine Learning to Accelerate Screening for Marcus Reorganization Energies

2021 ◽  
Author(s):  
Omri Abaarbanel ◽  
Geoffrey Hutchison
Keyword(s):  
Machine Learning ◽  
Charge Transport ◽  
Density Functional ◽  
Activation Barrier ◽  
Reorganization Energy ◽  
Transport Parameters ◽  
Light Emitting Devices ◽  
Wide Range ◽  
Important Challenge ◽  
Reorganization Energies

Understanding and predicting the charge transport properties of π-conjugated materials is an important challenge for designing new organic electronic applications, including solar cells, plastic transistors, light-emitting devices, and chemical sensors. A key component of the hopping mechanism of charge transfer in these materials is the Marcus reorganization energy, which serves as an activation barrier to hole or electron transfer. While modern density functional methods have proven to accurately predict trends in intramolecular reorganization energy, such calculations are computationally expensive. In this work, we outline active machine learning methods to predict computed intramolecular reorganization energies of a wide range of polythiophenes and their use towards screening new compounds with low internal reorganization energies. Our models have an overall root mean square error of ±0.113 eV, but a much smaller RMSE of only ±0.036 eV on the new screening set. Since the larger error derives from high-reorganization energy compounds, the new method is highly effective to screen for compounds with potentially efficient charge transport parameters.

scholarly journals Machine Learning to Accelerate Screening for Marcus Reorganization Energies

2021 ◽  
Author(s):  
Omri Abaarbanel ◽  
Geoffrey Hutchison
Keyword(s):  
Machine Learning ◽  
Charge Transport ◽  
Density Functional ◽  
Activation Barrier ◽  
Reorganization Energy ◽  
Transport Parameters ◽  
Light Emitting Devices ◽  
Wide Range ◽  
Important Challenge ◽  
Reorganization Energies

Understanding and predicting the charge transport properties of π-conjugated materials is an important challenge for designing new organic electronic applications, including solar cells, plastic transistors, light-emitting devices, and chemical sensors. A key component of the hopping mechanism of charge transfer in these materials is the Marcus reorganization energy, which serves as an activation barrier to hole or electron transfer. While modern density functional methods have proven to accurately predict trends in intramolecular reorganization energy, such calculations are computationally expensive. In this work, we outline active machine learning methods to predict computed intramolecular reorganization energies of a wide range of polythiophenes and their use towards screening new compounds with low internal reorganization energies. Our models have an overall root mean square error of ±0.113 eV, but a much smaller RMSE of only ±0.036 eV on the new screening set. Since the larger error derives from high-reorganization energy compounds, the new method is highly effective to screen for compounds with potentially efficient charge transport parameters.

scholarly journals Role of the reorganization energy for charge transport in disordered organic semiconductors

2021 ◽  
Vol 103 (16) ◽  
Author(s):  
R. Saxena ◽  
V. R. Nikitenko ◽  
I. I. Fishchuk ◽  
Ya. V. Burdakov ◽  
Yu. V. Metel ◽  
...  
Keyword(s):  
Charge Transport ◽  
Organic Semiconductors ◽  
Reorganization Energy

Design and Synthesis of Two-Dimensional Covalent Organic Frameworks with Four-Arm Cores: Prediction of Remarkable Ambipolar Charge-Transport Properties

2019 ◽  
Author(s):  
Simil Thomas ◽  
Hong Li ◽  
Raghunath R. Dasari ◽  
Austin Evans ◽  
William Dichtel ◽  
...  
Keyword(s):  
Charge Transport ◽  
Organic Semiconductors ◽  
Density Functional ◽  
Polymer Networks ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
X Ray Diffraction ◽  
Zinc Porphyrin ◽  
Design And Synthesis ◽  
Predicted Values

<p>We have considered three two-dimensional (2D) π-conjugated polymer networks (i.e., covalent organic frameworks, COFs) materials based on pyrene, porphyrin, and zinc-porphyrin cores connected <i>via</i> diacetylenic linkers. Their electronic structures, investigated at the density functional theory global-hybrid level, are indicative of valence and conduction bands that have large widths, ranging between 1 and 2 eV. Using a molecular approach to derive the electronic couplings between adjacent core units and the electron-vibration couplings, the three π-conjugated 2D COFs are predicted to have ambipolar charge-transport characteristics with electron and hole mobilities in the range of 65-95 cm<sup>2</sup>V<sup>-1</sup>s<sup>-1</sup>. Such predicted values rank these 2D COFs among the highest-mobility organic semiconductors. In addition, we have synthesized the zinc-porphyrin based 2D COF and carried out structural characterization via powder X-ray diffraction and surface area analysis, which demonstrates the feasability of these electroactive networks.</p>

Rational design and crystal structure prediction of ring-fused double-PDI compounds as n-channel organic semiconductors: a DFT study

2021 ◽  
Author(s):  
Suryakanti Debata ◽  
Smruti R. Sahoo ◽  
Rudranarayan Khatua ◽  
Sridhar Sahu
Keyword(s):  
Crystal Structure ◽  
Charge Transport ◽  
Organic Semiconductors ◽  
Structure Prediction ◽  
Rational Design ◽  
Molecular Design ◽  
Design Strategy ◽  
Dft Study ◽  
Crystal Structure Prediction ◽  
Model Compounds

In this study, we present an effective molecular design strategy to develop the n-type charge transport characteristics in organic semiconductors, using ring-fused double perylene diimides (DPDIs) as the model compounds.

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