Theoretical Investigation of Structural Effects on the Charge Transfer Properties in Modified Phthalocyanines

MRS Advances ◽  
2015 ◽  
Vol 1 (7) ◽  
pp. 453-458 ◽  
Author(s):  
Patrick J. Dwyer ◽  
Stephen P. Kelty
Keyword(s):  
Organic Semiconductors ◽  
Electron Affinity ◽  
Density Functional ◽  
Reorganization Energy ◽  
High Electron ◽  
Optoelectronic Materials ◽  
Research Attention ◽  
Efficient Charge ◽  
Reorganization Energies ◽  
P Type

ABSTRACTFor efficient charge separation and charge transport in optoelectronic materials, small internal reorganization energies are desired. While many p-type organic semiconductors have been reported with low internal reorganization energies, few n-type materials with low reorganization energy are known. Metal phthalocyanines have long received extensive research attention in the field of organic device electronics due to their highly tunable electronic properties through modification of the molecular periphery. In this study, density functional theory (DFT) calculations are performed on a series of zinc-phthalocyanines (ZnPc) with various degrees of peripheral per-fluoroalkyl (-C3F7) modification. Introduction of the highly electron withdrawing groups on the periphery leads to a lowering in the energy of the molecular frontier orbitals as well as an increase in the electron affinity. Additionally, all molecules studies are found to be most stable in their anionic form, demonstrating their potential as n-type materials. However, the calculated internal reorganization energy slightly increases as a function of peripheral modification. By varying the degree of modification we develop a strategy for obtaining an optimal balance between low reorganization energy and high electron affinity for the development of novel n-type optoelectronic materials.

The Electron Affinities of the Alkyldithio Radicals and their Anions

2012 ◽  
Vol 512-515 ◽  
pp. 2059-2063 ◽  
Author(s):  
Hui Yi Pei ◽  
Ai Fang Gao
Keyword(s):  
Electron Affinity ◽  
Density Functional ◽  
Basis Set ◽  
Electron Affinities ◽  
Hartree Fock ◽  
Functional Methods ◽  
Different Types ◽  
Vertical Detachment Energy ◽  
Vertical Electron Affinity ◽  
P Type

The electron affinities of the CnH2n+1SS/CnH2n+1SS- (n=1-5) species have been determined using four different density functional or hybrid Hartree-Fock density functional methods. The basis set used in this work is of double- plus polarization quality with additional diffuse s- and p-type functions, denoted DZP++. Three different types of the neutral-anion energy separations reported in this work are the adiabatic electron affinity (EAad), the vertical electron affinity (EAvert), and the vertical detachment energy (VDE). The most reliable adiabatic electron affinities, obtained at the DZP++ BP86 level of theory, are 1.794 eV (for CH3SS), 1.777 eV (for C2H5SS), 1.778 eV (a) and 1.809 eV (b) for the two isomers of C3H7SS, 1.782 eV (a), 1.825 eV (b) and 1.778 eV (c) for the three isomers of C4H9SS, and 1.784 eV (a), 1.875 eV (b), 1.805 eV (c) and 1.835 eV (d) for the three isomers of C5H11SS, respectively.

scholarly journals Reorganization energies of flexible organic molecules as a challenging target for machine learning enhanced virtual screening

2021 ◽  
Author(s):  
Ke Chen ◽  
Christian Kunkel ◽  
Karsten Reuter ◽  
Johannes T. Margraf
Keyword(s):  
Machine Learning ◽  
Virtual Screening ◽  
Organic Semiconductors ◽  
Organic Molecules ◽  
Predictive Accuracy ◽  
Molecular Design ◽  
Reorganization Energy ◽  
Charge Carrier Mobility ◽  
Design Rule ◽  
Reorganization Energies

The molecular reorganization energy $\lambda$ strongly influences the charge carrier mobility of organic semiconductors and is therefore an important target for molecular design. Machine learning (ML) models generally have the potential to strongly accelerate this design process (e.g. in virtual screening studies) by providing fast and accurate estimates of molecular properties. While such models are well established for simple properties (e.g. the atomization energy), $\lambda$ poses a significant challenge in this context. In this paper, we address the questions of how ML models for $\lambda$ can be improved and what their benefit is in high-throughput virtual screening (HTVS) studies. We find that, while improved predictive accuracy can be obtained relative to a semiempirical baseline model, the improvement in molecular discovery is somewhat marginal. In particular, the ML enhanced screenings are more effective in identifying promising candidates but lead to a less diverse sample. We further use substructure analysis to derive a general design rule for organic molecules with low $\lambda$ from the HTVS results.

scholarly journals Electron Transport in Naphthalene Diimide Derivatives

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4026
Author(s):  
Jaroslaw Jung ◽  
Arkadiusz Selerowicz ◽  
Paulina Maczugowska ◽  
Krzysztof Halagan ◽  
Renata Rybakiewicz-Sekita ◽  
...  
Keyword(s):  
Electron Transport ◽  
Organic Semiconductors ◽  
Density Functional ◽  
Low Voltage ◽  
Operating Conditions ◽  
High Electron ◽  
Voltage Range ◽  
Light Emitting ◽  
Naphthalene Diimide ◽  
Naphthalene Diimides

Two naphthalene diimides derivatives containing two different (alkyl and alkoxyphenyl) N-substituents were studied, namely, N,N′-bis(sec-butyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide (NDI-s-Bu) and N,N′-bis(4-n-hexyloxyphenyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide (NDI-4-n-OHePh). These compounds are known to exhibit electron transport due to their electron-deficient character evidenced by high electron affinity (EA) values, determined by electrochemical methods and a low-lying lowest unoccupied molecular orbital (LUMO) level, predicted by density functional theory (DFT) calculations. These parameters make the studied organic semiconductors stable in operating conditions and resistant to electron trapping, facilitating, in this manner, electron transport in thin solid layers. Current–voltage characteristics, obtained for the manufactured electron-only devices operating in the low voltage range, yielded mobilities of 4.3 × 10−4 cm2V−1s−1 and 4.6 × 10−6 cm2V−1s−1 for (NDI-s-Bu) and (NDI-4-n-OHePh), respectively. Their electron transport characteristics were described using the drift–diffusion model. The studied organic semiconductors can be considered as excellent candidates for the electron transporting layers in organic photovoltaic cells and light-emitting diodes

scholarly journals Exciton transport in molecular organic semiconductors boosted by transient quantum delocalization

2022 ◽  
Author(s):  
Samuele Giannini ◽  
Wei-Tao Peng ◽  
Lorenzo Cupellini ◽  
Daniele Padula ◽  
Antoine Carof ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Diffusion Constant ◽  
Reorganization Energy ◽  
Clear Correlation ◽  
Optoelectronic Materials ◽  
Surface Hopping ◽  
Exciton Transport ◽  
Organic Optoelectronic Devices ◽  
Organic Optoelectronic ◽  
Quantum Delocalization

Abstract Designing molecular materials with very large exciton diffusion lengths would remove some of the intrinsic limitations of present-day organic optoelectronic devices. Yet, the nature of excitons in these materials is still not sufficiently well understood. Here we present Frenkel exciton surface hopping, a highly efficient method to propagate excitons through truly nano-scale materials by solving the time-dependent Schrödinger equation coupled to nuclear motion. We find a clear correlation between diffusion constant and quantum delocalization of the exciton. In materials featuring some of the highest diffusion lengths to date, e.g. the non-fullerene acceptor Y6, the exciton propagates via a transient delocalization mechanism, reminiscent to what was recently proposed for charge transport. Yet, the extent of delocalization is rather modest, even in Y6, and found to be limited by the relatively large exciton reorganization energy. On this basis we chart out a path for rationally improving exciton transport in organic optoelectronic materials.

scholarly journals Remarkable charge-transfer mobility from [6] to [10]phenacene as a high performance p-type organic semiconductor

2018 ◽  
Vol 20 (13) ◽  
pp. 8658-8667 ◽  
Author(s):  
Thao P. Nguyen ◽  
P. Roy ◽  
Ji Hoon Shim
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Organic Semiconductors ◽  
High Performance ◽  
Density Functional ◽  
Dft Calculation ◽  
High Efficiency ◽  
Electronic Devices ◽  
Functional Theory ◽  
P Type

A density functional theory (DFT) calculation predicts phenacene as one of the most promising organic semiconductors for high efficiency electronic devices.

The influence of external electric fields on charge reorganization energy in organic semiconductors

2019 ◽  
Vol 55 (16) ◽  
pp. 2384-2387 ◽  
Author(s):  
Weicong Huang ◽  
Hu Shi ◽  
Hongguang Liu ◽  
Clémence Corminboeuf
Keyword(s):  
Electric Field ◽  
Organic Semiconductors ◽  
Electric Fields ◽  
Reorganization Energy ◽  
Ring Carbon ◽  
External Electric Fields ◽  
Anisotropic Character ◽  
Reorganization Energies

Charge reorganization energies (λ) of inter-ring carbon–carbon (IRCC) bond connected conjugated polycyclics are shown to exhibit an electric-field-driven anisotropic character.

scholarly journals Molecular orbital analysis of selected organic p-type and n-type conducting small molecules

2017 ◽  
Vol 10 (1) ◽  
pp. 6-16
Author(s):  
Denisa Cagardová ◽  
Vladimír Lukeš
Keyword(s):  
Small Molecules ◽  
Density Functional ◽  
Basis Set ◽  
Hybrid Functional ◽  
Electronic Band ◽  
Functional Theory ◽  
Reorganization Energies ◽  
Molecular Orbital Analysis ◽  
P Type ◽  
Orbital Analysis

Abstract In this article, the selected series of commercially available p-type and n-type semiconducting small molecules are systematically studied by density functional theory using the B3LYP hybrid functional and 6-311G(2d,p) basis set. The optimal geometries of each molecule in the electronic neutral and corresponding charged states are calculated. The evaluated energies of frontier molecular orbitals and electronic band gaps are mutually compared together with adiabatic electronic intramolecular reorganization energies. The chemical accuracy of the evaluated theoretical quantities is estimated from the comparison with available experimental data.

Synthesis of Unsymmetrically Functionalized Violanthrenes by Reductive Aromatization of Violanthrone 79

Synlett ◽  
2021 ◽  
Author(s):  
Simon Werner ◽  
Jörg Sundermeyer
Keyword(s):  
Organic Semiconductors ◽  
Density Functional ◽  
Low Cost ◽  
Sodium Dithionite ◽  
Frontier Molecular Orbital ◽  
Molecular Characteristics ◽  
Available N ◽  
Molecular Precursors ◽  
High Yields ◽  
P Type

The commercially available n-type semiconductive dye Violanthrone 79 is used as starting material to synthesize via a reductive aromatization and functionalization strategy so far unexplored substituted violanthrenes. Using the low-cost reducing agents zinc and sodium dithionite in combination with suitable electrophilic trapping reagents, three violanthrenes functionalized with two pivalyloxy, trimethylsiloxy or methoxy groups are selectively obtained in high yields. Due to their octyl ether moieties, these new red dyes are highly soluble. They are characterized by means of UV-Vis and fluorescence spectroscopy and their redox properties are studied via cyclic voltammetry. The spectroscopically determined frontier molecular orbital energies are compared to those calculated by density functional theory and suggest, that electron-poor Violanthrone 79 was transformed into electron-rich violonthrenes VE1-VE3 with molecular characteristics typically observed in molecular precursors for p-type organic semiconductors.

Theoretical investigations of charge carrier transport in organic semiconductors of naphthalene bisimides N-substituted with alkoxyphenyl groups

2015 ◽  
Vol 93 (7) ◽  
pp. 740-748 ◽  
Author(s):  
Jun Yin ◽  
Kadali Chaitanya ◽  
Xue-Hai Ju
Keyword(s):  
Density Functional Theory ◽  
Charge Carrier ◽  
Organic Semiconductors ◽  
Carrier Mobility ◽  
Density Functional ◽  
Reorganization Energy ◽  
Charge Carrier Mobility ◽  
Transport Processes ◽  
Functional Theory ◽  
Transfer Integral

Three novel alkoxyphenyl N-substituted naphthalene bisimide derivatives, N,N′-bis(4-n-butoxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI1), N,N′-bis(4-n-hexyloxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI2), and N,N′-bis(4-n-octyloxyphenyl)-1,8:4,5-naphthalenetetracarboxylic (NBI3) as potential organic semiconductors, have been investigated using density functional theory calculations coupled with the incoherent charge-hopping model at the molecular and crystal levels. The calculated results demonstrate that the low-lying and delocalized LUMOs and larger adiabatic electron affinities of these compounds are beneficial to their stability when acting as n-type organic semiconductors. The reorganization energy and transfer integral can significantly influence the charge carrier mobility. The compounds featured with the small reorganization energy and large transfer integral have relatively high charge mobilities. The electron coupling among the dominant hopping pathways indicates that the charge-transport processes happen in the parallel dimer of neighboring molecules with π–π interaction. The investigation of the angle dependence of charge carrier mobility showed that both NBI1 and NBI3 crystals exhibit remarkable anisotropic charge transporting behaviors. The calculated absorption spectra by the time-dependent density functional theory revealed that the strongest absorption peaks in the visible region are assigned to the π → π* transition and these peaks are regulated by the transitions of HOMO → LUMO. The calculated electron mobilities of NBI1, NBI2, and NBI3 are 0.0365, 0.0312, and 0.0801 cm2 V–1 s–1, respectively, indicating that these compounds are suitable for n-type organic semiconductors.

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.

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