Influence of the Halogenated Substituent on Charge Transfer Mobility

Article pubs.acs.org/JPCC

Influence of the Halogenated Substituent on Charge Transfer Mobility of Aniline Tetramer and Derivatives: Remarkable Anisotropic Mobilities Yahong Zhang,† Yuping Duan,*,† Jia Liu,† Daoyuan Zheng,§ Mingxing Zhang,‡,§ and Guangjiu Zhao*,‡,§ †

Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116085, P. R. China ‡ Tianjin Key Laboratory of Molecular Optoelectr-onic Science, Institute of Chemistry, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, P. R. China § State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian 116023, P. R. China ABSTRACT: The halogen-substituted derivatives and the parent aniline tetramer as organic semiconductors have been theoretically investigated with a focus on the electronic properties and charge transport properties through density functional theory and Marcus−Hush theory methods. The study on the transport properties of holes and electrons can obtain insight into the effect of halogenation substitution on injection of charge carriers and transport character. The equilibrium geometries, reorganization energies, frontier molecular orbitals, intermolecular electronic couplings, electrostatic potential isosurfaces, and angular resolution anisotropic mobilities were calculated. The calculated results revealed that perfluorination and perchlorination can induce stronger structure relaxation and effectively lower the highest occupied molecular orbital and lowest unoccupied molecular orbital levels. The angle dependence mobilities of the three crystals show remarkable anisotropic character. The carrier mobility curves for both electron and hole transport of the parent aniline tetramer and halogen-substituted derivatives all show a remarkable anisotropic feature. Furthermore, the ANIH and ANICl crystals show higher electron-transfer mobilities than hole-transfer mobilities and, hence, perform better as an n-type organic semiconductor. The ANIH crystal possesses a low reorganization energy combined with a high electronic coupling and electron-transfer mobility, which indicates that the ANIH crystal might be a more ideal candidate as an n-type organic semiconductor material.

■

semiconductor materials.8−22 For example, adding electronwithdrawing groups or substituents is the general idea to design an n-type organic semiconductor. The addition of fluorine, bromine, and imide moieties will lower the lowest unoccupied molecular orbital (LUMO) energy and further heighten electron affinities.23,24 There have been some theoretical studies about the halogenated effect on oligoacenes.25−32 Some electronic devices based on partly halogenated pentacene show an ambipolar feature.13 For the purpose of getting the n-type pentacene semiconductor, the usual way is to involve a full halogenated pentacene backbone, especially for fluorine atoms. The effects of perfluorination on the charge-transport properties of organic semiconductors was studied systematacially.25−28 The perfluorinated oligothiophenes are more difficult to oxidize and show a larger band gap compared with their nonsubstituted parent compounds.25−27 Zhang et al. have studied the effects of

INTRODUCTION Organic semiconductor materials based on π-conjugated characteristics are of increasing attractiveness in recent years for their wide applications in optoelectronic and microelectronic devices, for example, organic field-effect transistors,1 organic light-emitting diodes,2 organic solar cells, and organic photovoltaic devices.3,4 For these applications, to explore the crucial electronic properties of organic semiconductor materials would be especially important, and the charge-transport property is the key factor for the performance of an electronic device. The charge-hopping rate is mainly related to the intermolecular electronic couplings which are dependent on crystal packing patterns.5 The research of the relationship between the structure properties and carrier mobility is extremely important.6,7 Up to now, many investigations have been widely carried out based on modified organic semiconductor materials which possess both high carrier mobility and excellent stability in ambient atmosphere. The proper molecular structure designs were proven to be an effective way to enhance the intermolecular interaction and increase the charge mobility of © XXXX American Chemical Society

Received: May 23, 2017 Revised: July 18, 2017 Published: August 8, 2017 A

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C introducing fluorine into aryl substituted tetracene. The research demonstrated that, compared with the nonfluorinated structure, the fluorinated derivative showed the improved charge mobility which can be attributed to the favorable molecular packing caused by the increased π−π interaction.28 Tang et al. studied the chlorination on electron transport in organic semiconductors, and the results show that adding chlorine atoms to conjugated cores is an effective way to design n-type air-stable organic semiconductors. The LUMO energy and the charge injection barrier for electrons were lowered by the introduction of electron-withdrawing halogen groups, which benefits the electron and hole transport simultaneously.10 Polyaniline (PANI) as a conjugated organic semiconductor material has gained enormous attention and wide application due to excellent properties.33−39 There have been many theoretical calculations devoted to investigate the geometric structure, doping mechanism, hydrogen bonding effect, band structure, conductivity, etc.40−43 To the best of our knowledge, theoretical investigations on charge transport properties of halogenated PANI derivatives and the performance of PANI as conjugated organic semiconductors have not been thoroughly performed to date. In this work, the charge transport properties of phenyl-endcapped tetramer of aniline (ANIH) and halogenated PANI derivatives, i.e., perfluorinated tetramer (ANIF) as well as perchlorinate tetramer (ANICl), were fully investigated through first-principles quantum mechanics calculation. The crystal structure of ANIH was acquired from the online Cambridge Crystallographic Data Centre based on ref 44. Crystal structures of ANIF and ANICl were optimized using Materials Studio software. As is well-known, the charge mobilities are strongly dependent on two parameters, reorganization energy and intermolecular electronic coupling.45−47 The large electronic coupling and low reorganization energy are desired for high mobility. The transport properties of ANIH, ANIF, and ANICl were calculated, and the influences of halogenation substitution on the charge mobility were assessed. The theoretical prediction of the relationship between the molecular modification and charge mobility is a promising way to design organic semiconductors with high performance.

spatial dimensionality, i is the ith pathway, ri represents the hopping distance of the dimer, W is the hopping rate, t is the time, and P is the intermolecular hopping probability which is calculated from Pi = Wi /∑i Wi . The band-like model and the hopping model have been put forward to explore the charge transport performance in organic semiconductor materials. Taking into consideration that charge carriers are localized on a single molecule due to the weak van der Waals forces, the thermally activated hopping model has been confirmed to be the preferred mechanism for the carrier mobilities prediction in semiconductor crystals. Based on the Marcus−Hush theory,49,50 the hopping rate W can be described as 2 ⎛ λ ⎞ V2 ⎛ π ⎞ W= ⎜ ⎟ exp⎜ − ⎟ ℏ ⎝ λkBT ⎠ ⎝ 4kBT ⎠

where ℏ is the Planck constant, λ is the reorganization energy, and V is the intermolecular electronic coupling. As shown above, the reorganization energy λ and the effective electronic coupling V are the crucial importance parameters for the charge hopping rate evaluation; therefore, broad scale research has been done to improve the charge mobilities in organic semiconductor materials through optimization of these two parameters.51−53 The reorganization energy usually contains two parts, i.e., the inner and outer contributions. The external reorganization energy arises from the nuclear and electronic relaxation or polarization of the surrounding medium. In our calculation, only the internal reorganization energy is taken into account, and the outer reorganization energy could be neglected due to the weak contribution from the surrounding molecules.54,55 However, the neglect of the outer reorganization energy will overestimate the hopping rate as well as the carrier mobility for organic semiconductors. The adiabatic potential energy surface method is the most common way to calculate the reorganization energy λ in the solid state:56−58 λ = λ1 + λ 2 = (E0* − E0) + (E+*/ − − E+ / −)

where E0 is the energy of neutral state in lowest energy geometry, E± is the energy of cation/anion state in lowest energy geometries, E*0 is the energy of the neutral monomer with the cation geometry, E±* the energy of the cation/anion monomers with the neutral geometries, and λ1 and λ2 represent the relaxation energies. The adiabatic ionization potential (IP) and the electron affinity (EA) can be evaluated from the following equations:

■

THEORETICAL AND COMPUTATIONAL METHOD The charge mobility in molecule indicates their transport ability, which is one of the most important criteria for evaluating the transport type of the organic semiconductor material. In most conjugated organic oligomer crystals, the orientation and stacking patten of organic molecules will be affected by the weak van der Waals forces, and as a result, the charge carriers on the single molecule will be slightly limited by the weak electronic coupling. The assumption is made that the charge hopping processes are uncorrelated and the hopping motions are homogeneous random walk,21,45−48 and the hopping drift mobility μ is calculated based on the Einstein relation μ=

e e 1 x(t 2) e D= lim ≈ kBT kBT n →∞ 2n t 2nkBT

IP = E+ − E0

EA = E0 − E− The monomer molecules in their charged states or neutral states are all optimized, and the corresponding reorganization energies are also calculated. The density functional theory (DFT) with B3LYP functional, which has been proved to perform rather well in the study of conjugated organic models including PANI oligomer,59−61 was used throughout the calculation, and 6-31G(d, p) was the basis set in the whole process. The total calculations are supported by the Gaussian 09 program. The intermolecular electronic coupling represents the strength of electronic coupling between the adjacent molecules, which is evaluated from the site-energy correction method

∑ ri 2WP i i i

2

where D is the diffusion coefficient, x denotes the mean-square displacement of charges, T is the temperature (298 K in our calculation), kB is the Boltzmann constant, n represents the B

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C based on the molecular orbitals of the conjugated molecules.62−64 The site energies (HPP and HRR), charge transfer integrals (JRP), and spatial overlap (SRP) for each dimer are the crucial parameters for electronic coupling calculation, which can be computed directly using density functional theory (DFT) by Amsterdam density functional (ADF) program. The electronic coupling V was finally calculated from the following equation: V=

JRP − SRP(HRP + HPP)/2 1 − SRP 2

In the calculation, the local density functional VWN in conjunction with PW91 gradient corrections are used for the electronic coupling evaluation, and the TZ2P was set as the basis set in the whole process.63,64 The field-effect mobility in a particular transistor channel is affected by the specific surface of the organic crystal. The anisotropic character verified that the angles of the hopping pathway between adjacent molecules are interrelated to the carrier mobility for each surface. The mobilities of different hopping pathways have been predicted by the anisotropic mobility simulation,21,46,47 and the angular resolution anisotropic mobility μϕ can be calculated from the following equation: μϕ =

e 2kBT

Figure 1. Optimized molecular structures of ANIH, ANIF, and ANICl.

2 2 ∑ ri 2WP i i cos γi cos (θi − ϕ) i

where θi is the conducting channel relative to the reference axis, γi is the angle of the hopping pathway relative to the transport plane in the crystal molecular stacking layer, and Φ is the orientation angle of the projected electronic coupling pathways.

■

RESULTS AND DISCUSSION As is well-known, the molecular structure can influence the intermolecular interaction significantly and then affect the molecular packing in the crystal.22,65,66 The ground-state geometries for ANIH, ANIF, and ANICl molecules were optimized. Afterward, the frequency analysis was taken into account, and no imaginary frequency was found. The singlepoint calculations were carried out based on the optimized geometries for further analysis of the reorganization energy. The optimized structures in neutral states are shown in Figure 1. It can be found that the three molecules with planar rings are both hexacyclic conjugated. In molecules of ANIF and ANICl, the planar structures were destroyed by the substitution of hydrogen atoms with fluorine or chlorine atoms. THe ANIH molecule possesses the largest π-conjugation compared with ANIF and ANICl molecules, due to its planar strcture. The bond characteristics of ANIH, ANIF, and ANICl molecules are shown in Figure 2. The main diagram shows the characteristic bond lengths of the molecules. Taking into account the symmetry properties of the molecules, only the selected 20 chemical bonds are listed and labeled in the molecular skeleton. It is obvious that the C−C bonds in the conjugated rings and the N−H bonds almost remain unchanged. To compare the geometrical relaxations for three molecules, the changes of bond length (ΔR) are shown in the inserted diagram in Figure 2 which were calculated as follow: ΔR i =

|R icharged − R ineutral| R ineutral

Figure 2. Bond lengths and bond length change values of key chemical bond for ANIH, ANIF, and ANICl.

where Rcharged and Rneutral refer to bond lengths of charged and i i neutral molecules, respectively. The similar structural relaxation on the aromatic rings can be seen, and the bond length changes of C−C bonds are quite small. However, the bond length changes of C−F bonds and C−Cl bonds are obviously larger than those of C−H bonds which means that the halogenated derivatives possess the stronger relaxation and the higher reorganization energies. To quantitatively describe the geometric variation in the charge process, the average values of bond length changes for all C−C bonds in the molecule skeletons are calculated. The results show that the substitutions of fluorine atoms with strong electron-withdrawing ability lead to the reduction of the C−C bond lengths of about 0.0049 Å. However, the chlorine substitutions with weak electrondonating ability induce an elongation of about 0.0026 Å. This phenomenon is due to the conjugated effect of the vacant 3d orbitals in Cl atoms which has been mentioned in a previous report.10,13,66 The reorganization energies (λ), ionization potentials (IP), and electron affinities (EA) are obtained from the single-point energies through the adiabatic potential energy surface method.

× 100% C

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C The general regulation is accepted that lower reorganization energy is favorable for achieving higher carrier mobility.53,67,68 As is shown in Table 1, the reorganization energies for electron

The molecular packing motif of the organic crystal is the determining factor for the intermolecular electronic coupling and carrier mobility. For the purpose of understanding the halogenated substituent effects on charge transport properties, the molecular packing styles of crystals ANIH, ANIF, and ANICl are shown in Figure 4. The hopping distances and the angles between the hopping pathways and the reference axis of the dimers are also listed in Figure 4. It is clear that all of the packing structures show a herringbone characteristic, and there are two packing modes: face-to-edge style for T1 and T2 dimers and face-to-face stacking for the P dimer. The coupling area of the conjugated planes significantly influence the mobility, and the larger effective coupling and smaller distance of conjugated center are beneficial to molecular design and performance improvement. The intermolecular electronic couplings for the nearest neighbor dimers as the crucial parameter are listed in Table 2. The phenomenon can be found that the electronic couplings of different channels in ANIF and ANICl crystals are generally smaller than that in the ANIH crystal. The smaller electronic couplings may be due to the increased hopping distance of ANIF and ANICl crystals. For the ANIH crystal, the hole-transport electronic couplings Vh of all of the channels are much smaller than the electron-transport electronic couplings Ve. The pathway P shows the largest electronic coupling, and parallel cofacial stacking is usually expected to offer a much larger coupling and more efficient orbital overlap. The larger Ve combined with the lower electron reorganization energy indicates that the ANIH crystal may function as n-type organic semiconductor materials. The electron-transport electronic couplings of ANIF are larger than the hole-transport electronic couplings which indicates that the ANIF tends to be an n-type organic semiconductor material. It is well-known that the molecular solid-state arrangements could be sensitive to various intermolecular interactions and strongly influence the charge transport behavior. The electrostatic potential (ESP)69−72 which could be used to analyze the noncovalent interactions has been studied in detail. The electrostatic potential isosurfaces of the investigated molecules in the neutral, cation, and anion states are shown in Figure 5. The visible results show that, for the neutral state, the most negative areas of the electrostatic potentials are located on the skeleton of the π-conjugated core of AHIH; however, the electrostatic potentials on the conjugated aromatic rings of AHIF and AHICl turn out to be positive due to the strong electron-withdrawing feature of the introduced halogen atoms. The uniform conclusion for the neutral states is that the maximum positive potentials of AHIH, AHIF, and AHICl are mainly concentrated on the hydrogen atoms involved in N−H bonds. The cation and anion states of the three moleculars show their corresponding positive and negative characteristics. The main positive and negative areas distribute on the conjugated core. The partial charge difference value of ΔCC on the conjugated aromatic rings is defined as70

Table 1. Reorganization Energy (λh and λe), Ionization Potentials (IP), and Electron Affinities (EA) of ANIH, ANIF, and ANICl molecule

λh (eV)

λe (eV)

IP (eV)

EA (eV)

ANIH ANIF ANICl

0.2946 0.2765 0.3352

0.1339 0.1996 0.4238

5.2458 6.4310 6.7287

−0.6870 0.3372 1.1471

transfer λe of ANIH and ANIF are all much smaller than the hole transfer λh; therefore, ANIH and ANIF are proposed to be more efficient n-type than p-type organic semiconductors. Meanwhile, the reorganization energies of ANICl shows the opposite trend that the electron transfer λe is much larger than hole transfer λh which means that the ANICl crystal might prefer the p-type character. The ANIH possessing the smallest electron transfer λe is expected to function as a more efficient ntype organic semiconductor. The ionization potential (IP) and electron affinity (EA) of organic compounds are the important parameters to characterize their oxidation and reduction stabilities and have been approved to be significant factors to evaluate the charge-transfer efficiency of semiconductor materials. The ANIH monomer shows the lowest IP, which could facilitate the injection of charge carriers. The large EA value can improve the stability of the anions in ambient atmosphere, which is beneficial to the performance as n-type organic semiconductor materials. The frontier molecular orbitals of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are all shown in Figure 3. It can be observed

Figure 3. Frontier molecular orbitals of ANIH, ANIF, and ANICl monomers.

that the three systems keep a quite similar electron density distribution, and large conjugated systems are more inclined to delocalize on the middle aromatic rings due to the chain terminal effect. It is obvious that the HOMO and LUMO energies are all decreased when the halogen atoms are introduced to the parent aniline tetramer. Additionally, the chlorine substituted derivative slightly further reduces orbital energies, which is attributed to the enhanced overlap between the vacant 3d orbitals in chlorines.10,13

ΔCC =

∑ CCcharged − ∑ CCneutral i

i

i

i

where the Ccharged and Cneutral represent the charges of the ith Ci Ci carbon atom on the conjugated chain for the charged and neutral states, respectively. The partial charge difference values of other main atoms on the chain are also calculated based on D

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C

Figure 4. Charge hopping pathway schemes in the a−b plane of ANIH, ANIF, and ANICl crystals.

Table 2. Calculated Hole-Transport Electronic Couplings Vh and Electron-Transport Electronic Couplings Ve for Different Hopping Pathways in ANIH, ANIF, and ANICl Crystals ANIH

ANIF

ANICl

pathway

Vh (meV)

Ve (meV)

Vh (meV)

Ve (meV)

Vh (meV)

Ve (meV)

P T1 T2

23.6469 5.7864 5.5379

52.4503 24.4207 35.6352

0.2349 0.9452 0.1611

3.7911 22.0478 24.3068

3.5587 7.5031 9.2565

1.4603 3.6713 6.6132

Figure 5. Molecular surface electrostatic potentials of ANIH, ANIF, and ANICl in the neutral, cation, and anion states (scale bar: |e| in atomic unit).

the same method, and in order to facilitate comparison, only the hydrogen atoms involved in N−H bonds are taken into consideration. Figure 6 shows the total charge values (neutral, cation, and anion) and the charge difference values (cation− neutral and anion−neutral) of the key atoms on the conjugated skeletons. For all molecules, similar total charge distribution characteristics of neutral and charged states can be found that the total charges of nitrogen atoms remain unchanged during the halogen atoms replacing process, and the total charges of the carbon atoms change from negative to positive due to the electron-withdrawing substituent. The inset in the figure of partial charge difference values indicates that the substituent effect can be revealed in the charge difference values between the charged and neutral states. The multiple linear regression is used to describe the relationship between the partial charge difference values and reorganization energy.73−75 It is has been illustrated that the decrease of the reorganization energy due to the extension of the electron delocalization in a nonbonding fashion will result in a greater partial charge difference distributed on the conjugate backbone.74 The presumption can be made that the reorganization energies for hole transfer λh should be larger than the reorganization energies for electron transfer λe which results in smaller charge differences between the cation and neutral states than the corresponding charge differences between the anion and neutral states.

Figure 6. Partial charge difference values between the cation and neutral states (cation−neutral) as well as partial charge difference values between the anion and neutral states (anion−neutral) for the ANIH, ANIF, and ANICl molecules on the conjugated backbone. The total charge of the atoms for the neutral, cation, and anion states are also shown.

E

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C

Figure 7. Simulated angular resolution anisotropic mobility of ANIH, ANIF, and ANICl crystals.

ANIF and ANICl crystals, and the electron-transport electronic couplings of all of the channels are much larger than the holetransport electronic couplings; that is to say, ANIH should be more favorable to function as an n-type organic semiconductor than ANICl. In addition, electrostatic potentials on the πconjugated core change from negative to positive with substitution of halogen atoms with strong electron-withdrawing character. Moreover, the carrier mobility curves of ANIH, ANIF, and ANICl all show the remarkable anisotropic feature, and ANIH possesses the largest carrier mobility. Results show that the halogenated substituent plays an important role in determining the electronic properties and molecular stacking. A theoretical study on the charge transport behaviors of organic semiconductors is helpful for designing higher performance electronic materials.

The individual molecular packing styles and the differences of electronic couplings in various charge hopping directions lead to the mobility anisotropy, which has been described in Figure 7. The carrier mobility curves for both electron and hole transport of ANIH, ANIF, and ANICl all show the remarkable anisotropic feature. The maximum mobility μmax of ANIH crystal is 1.3893 cm2 V−1 s−1 which appears at near 176/356°, and the maximum value μmax of electron transfer mobility is extremely close to the pathway μP, which may due to the largest electron-transport electronic couplings Ve. It is can be observed that the ANIH crystal shows the largest carrier mobility, and both the parent ANIH and fluorinated ANIF have the inherent transfer mobility for electron transport that is larger than that for the corresponding hole transport, which further confirms that both the ANIH and ANIF crystals prefer to be n-type organic semiconductor materials, and the ANIH crystal should be the more ideal candidate. The conclusions are consistent with the previous predictions based on electronic couplings and reorganization energies. Theoretical simulations will provide a more reasonable analysis of the intrinsic charge transport properties by ignoring the details of the experimental conditions, and the understanding of the angular resolution anisotropic characteristic will provide the guidance for the improvement of organic semiconductor materials and design of the organic electronic devices.

■

AUTHOR INFORMATION

Corresponding Authors

*Tel: +8641184708446. Fax: +86411 84708446. E-mail: [email protected]. *E-mail: [email protected]. ORCID

Yuping Duan: 0000-0001-5599-7168 Notes

■

The authors declare no competing financial interest.

■ ■

CONCLUSION The charge transfer mobility characteristics of the parent ANIH tetramer and halogen substituted derivatives ANIF and ANICl are theoretically investigated in this study. Based upon DFT calculation results, the introduction of fluorine atoms and chlorine atoms will induce a structural twist on the conjugated skeleton, and meanwhile, the F-substitution and Cl-substitution show the larger bond length changes than that for the aniline tetramer which means that the substituted derivatives possess a stronger relaxation and, hence, the higher reorganization energies. The HOMO and LUMO energies are all decreased with the introduction of halogen atoms especially for the chlorine substituted derivative. The electronic couplings of different channels in ANIH are generally larger than that in

ACKNOWLEDGMENTS The authors acknowledge support from the Program for the National Natural Science Foundation of China (No. 51577021) REFERENCES

(1) Madison, T. A.; Gagorik, A. G.; Hutchison, G. R. Charge Transport in Imperfect Organic Field Effect Transistors: Effects of Charge Traps. J. Phys. Chem. C 2012, 116, 11852−11858. (2) Di, B.; Meng, Y.; Wang, Y. D.; Liu, X. J.; An, Z. An, Z. Electroluminescence Enhancement in Polymer Light-emitting Diodes Through Inelastic Scattering of Oppositely Charged Bipolarons. J. Phys. Chem. B 2011, 115, 9339−9344. (3) Tamayo, A. B.; Walker, B.; Nguyen, T. Q. A Low Band Gap, Solution Processable Oligothiophene with a Diketopyrrolopyrrole

F

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C Core for Use in Organic Solar Cells. J. Phys. Chem. C 2008, 112, 11545−11551. (4) Leclerc, N.; Chávez, P.; Ibraikulov, O. A.; Heiser, T.; Lévêque, P. Impact of Backbone Fluorination on π-conjugated Polymers in Organic Photovoltaic Devices: A Review. Polymers 2016, 8, 11. (5) Yang, X.; Wang, L.; Wang, C.; Long, W.; Shuai, Z. Influences of Crystal Structures and Molecular Sizes on the Charge Mobility of Organic Semiconductors: Oligothiophenes. Chem. Mater. 2008, 20, 3205−3211. (6) Yin, J.; Chaitanya, K.; Ju, X. H. Theoretical Study on Charge Mobilities of Pentafluorophenyl-appended Bisthiazole Derivatives. Comput. Theor. Chem. 2015, 1062, 56−64. (7) Zhao, C.; Wang, W.; Ma, Y. Molecular Design toward Good Hole Transport Materials Based on Anthra [2, 3-c] thiophene: A Theoretical Investigation. Comput. Theor. Chem. 2013, 1010, 25−31. (8) Wang, X.; Lau, K. C. Theoretical Investigations on Chargetransfer Properties of Novel High Mobility n-Channel Organic Semiconductors−diazapentacene Derivatives. J. Phys. Chem. C 2012, 116, 22749−22758. (9) Jones, B. A.; Facchetti, A.; Wasielewski, M. R.; Marks, T. J. Tuning Orbital Energetics in Arylene Diimide Semiconductors. Materials Design for Ambient Stability of n-Type Charge Transport. J. Am. Chem. Soc. 2007, 129, 15259−15278. (10) Tang, M. L.; Oh, J. H.; Reichardt, A. D.; Bao, Z. Chlorination: A General Route toward Electron Transport in Organic Semiconductors. J. Am. Chem. Soc. 2009, 131, 3733−3740. (11) Zhang, M. X.; Zhao, G. J. Heteroatomic Effects on ChargeTransfer Mobility of Dianthra [2, 3-b: 2′, 3′-f] thieno [3, 2-b] thiophene (DATT) and Its Derivatives. J. Phys. Chem. C 2012, 116, 19197−19202. (12) Zhang, X. Y.; Huang, J. D.; Yu, J. J.; Li, P.; Zhang, W. P.; Frauenheim, T. Anisotropic Electron-Transfer Mobilities in Diethynylindenofluorene-diones Crystals as High-Performance n-Type Organic Semiconductor Materials: Remarkable Enhancement by Varying Substituents. Phys. Chem. Chem. Phys. 2015, 17, 25463−25470. (13) Fan, J. X.; Chen, X. K.; Zhang, S. F.; Ren, A. M. Theoretical Study on Charge Transport Properties of Intra-and Extra-Ring Substituted Pentacene Derivatives. J. Phys. Chem. A 2016, 120, 2390−2400. (14) Zhao, G. J.; Yu, F.; Zhang, M. X.; Northrop, B. H.; Yang, H.; Han, K. L.; Stang, P. J. Substituent Effects on the Intramolecular Charge Transfer and Fluorescence of Bimetallic Platinum Complexes. J. Phys. Chem. A 2011, 115, 6390−6393. (15) Chai, S.; Wen, S. H.; Han, K. L. Understanding Electronwithdrawing Substituenteffect on Structural, Electronic and Charge Transport Properties of Perylenebisimide Derivatives. Org. Electron. 2011, 12, 1806−1814. (16) Lin, L.; Geng, H.; Shuai, Z.; Luo, Y. Theoretical Insights into the Charge Transport in Perylene Diimides Based n-Type Organic Semiconductors. Org. Electron. 2012, 13, 2763−2772. (17) Zhao, C.; Guo, Y.; Guan, L.; Ge, H.; Yin, S.; Wang, W. Theoretical Investigation on Charge Transport Parameters of Two Novel Heterotetracenes as Ambipolar Organic Semiconductors. Synth. Met. 2014, 188, 146−155. (18) Chai, S.; Wen, S. H.; Huang, J. D.; Han, K. L. Density Functional Theory Study on Electron and Hole Transport Properties of Organic Pentacene Derivatives with Electron-Withdrawing Substituent. J. Comput. Chem. 2011, 32, 3218−3225. (19) Zhang, S. F.; Chen, X. K.; Fan, J. X.; Ren, A. M. Charge Transport Properties in a Series of Five-ring-fused Thienoacenes: a Quantum Chemistry and Molecular Mechanic Study. Org. Electron. 2013, 14, 607−620. (20) Zhang, S. F.; Chen, X. K.; Fan, J. X.; Ren, A. M. Rational Design of Bio-inspired High-Performance Ambipolar Organic Semiconductor Materials Based on Indigo and its Derivatives. Org. Electron. 2015, 24, 12−25. (21) Huang, J. D.; Wen, S. H.; Deng, W. Q.; Han, K. L. Simulation of Hole Mobility in α-Oligofuran Crystals. J. Phys. Chem. B 2011, 115, 2140−2147.

(22) Zhang, X. Y.; Zhao, G. J. Anisotropic Charge Transport in Bisindenoanthrazoline-based n-Type Organic Semiconductors. J. Phys. Chem. C 2012, 116, 13858−13864. (23) Zhang, W. W.; Zhong, X. X.; Zhao, Y. Electron Mobilities of nType Organic Semiconductors from Time-Dependent Wavepacket Diffusion Method: Pentacenequinone Derivatives. J. Phys. Chem. A 2012, 116, 11075−11082. (24) Kitamura, C. In Methods and Applications of Cycloaddition Reactions in Organic Syntheses; Nishiwaki, N., Eds.; John Wiley & Sons: Hoboken, NJ, 2013; Chapter 14, pp 407−428. (25) Raya, A.; Mora, M. A. Theoretical Study of Perfluorinated Oligothiophenes: Electronic and Structural Properties. Polymer 2004, 45, 6391−6397. (26) Chen, H. Y.; Chao, I. Effect of Perfluorination on the ChargeTransport Properties of Organic Semiconductors: Density Functional Theory Study of Perfluorinated Pentacene and Sexithiophene. Chem. Phys. Lett. 2005, 401, 539−545. (27) Tang, M. L.; Reichardt, A. D.; Wei, P.; Bao, Z. Correlating Carrier Type with Frontier Molecular Orbital Energy Levels in Organic Thin Film Transistors of Functionalized Acene Derivatives. J. Am. Chem. Soc. 2009, 131, 5264−5273. (28) Zhang, B.; Kan, Y. H.; Geng, Y.; Duan, Y. A.; Li, H. B.; Hua, J.; Su, Z. M. An Efficient Strategy for Improving Carrier Transport Performance−Introducing Fluorine into Aryl Substituted Tetracene. Org. Electron. 2013, 14, 1359−1369. (29) Okamoto, K.; Nakahara, K.; Saeki, A.; Seki, S.; Oh, J. H.; Akkerman, H. B.; Bao, Z.; Matsuo, Y. Ary-Perfluoroaryl Substituted Tetracene: Induction of Face-to-Face π-π Stacking and Enhancement of Charge Carrier Properties. Chem. Mater. 2011, 23, 1646−1649. (30) Chai, S.; Huang, J. D. Impact of the Halogenated Substituent on Electronic and Charge Transport Properties of Organic Semiconductors: A Theoretical Study. Comput. Theor. Chem. 2015, 1069, 48−55. (31) Dou, J. H.; Zheng, Y. Q.; Yao, Z. F.; Yu, Z. A.; Lei, T.; Shen, X.; Luo, X.; Sun, J.; Zhang, S. D.; Ding, Y. F.; et al. Fine-Tuning of Crystal Packing and Charge Transport Properties of BDOPV Derivatives through Fluorine Substitution. J. Am. Chem. Soc. 2015, 137, 15947− 15956. (32) Guo, Y.; Wang, W.; Shao, R.; Yin, S. Theoretical Study on The Electron Transport Properties of Chlorinated Pentacene Derivatives. Comput. Theor. Chem. 2015, 1057, 67−73. (33) Jaymand, M. Recent Progress in Chemical Modification of Polyaniline. Prog. Polym. Sci. 2013, 38, 1287−1306. (34) Qazi, T. H.; Rai, R.; Boccaccini, A. R. Tissue Engineering of Electrically Responsive Tissues Using Polyaniline Based Polymers: A Review. Biomaterials 2014, 35, 9068−9086. (35) Choi, I. Y.; Lee, J.; Ahn, H.; Lee, J.; Choi, H. C.; Park, M. J. High-Conductivity Two-Dimensional Polyaniline Nanosheets Developed on Ice Surfaces. Angew. Chem., Int. Ed. 2015, 54, 10497−10501. (36) Jiang, J. K.; Liang, Q. H.; Meng, R. S.; Yang, Q.; Sun, X.; Yang, D. G.; Zhang, G. Q.; Chen, X. P. The Influence of Tensile Stress on Polyaniline as Strain Sensor. IEEE Electron Device Lett. 2016, 37, 1636−1638. (37) Malik, M. S.; Qaiser, A. A.; Arif, M. A. Structural and Electrochemical Studies of Heterogeneous Ion Exchange Membranes Based on Polyaniline-Coated Cation Exchange Resin Particles. RSC Adv. 2016, 6, 115046−115054. (38) Liang, Q. H.; Jiang, J. K.; Ye, H. Y.; Yang, N.; Cai, M.; Xiao, J.; Chen, X. P. Sorption and Diffusion of Water Vapor and Carbon Dioxide in Sulfonated Polyaniline as Shemical Eensing Materials. Sensors 2016, 16, 606. (39) Baker, C. O.; Huang, X.; Nelson, W.; Kaner, R. B. Polyaniline Nanofibers: Broadening Applications for Conducting Polymers. Chem. Soc. Rev. 2017, 46, 1510−1525. (40) Laabd, M.; El Jaouhari, A.; Chafai, H.; Bazzaoui, M.; Kabli, H.; Albourine, A. Experimental and Theoretical Studies on the Removal of Polycarboxy-Benzoic Acids by Adsorption onto Polyaniline from Aqueous Solution. Desalin. Water Treat. 2016, 57, 15176−15189. G

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C

versus Bipolaronic Configuration. J. Phys. Chem. B 2011, 115, 3765− 3776. (62) Valeev, E. F.; Coropceanu, V.; da Silva Filho, D. A.; Salman, S.; Bredas, J. L. Effect of Electronic Polarization on Charge-Transport Parameters in Molecular Organic Semiconductors. J. Am. Chem. Soc. 2006, 128, 9882−9886. (63) Te Velde, G.; Bickelhaupt, F. M.; Baerends, E. J.; Fonseca Guerra, C.; Van Gisbergen, S. J. A.; Snijders, J. G.; Ziegler, T. Chemistry with ADF. J. Comput. Chem. 2001, 22, 931−967. (64) Senthilkumar, K.; Grozema, F. C.; Bickelhaupt, F. M.; Siebbeles, L. D. A. J. Charge Transport in Columnar Stacked Triphenylenes: Effects of Conformational Fluctuations on Charge Transfer Integrals and Site Energies. J. Chem. Phys. 2003, 119, 9809−9817. (65) Huang, J. D.; Chai, S.; Ma, H.; Dong, B. Impact of Edge-Core Structures and Substituent Effects on the Electronic and ChargeTransport Properties of Heteroaromatic Ring-Fused Oligomers. J. Phys. Chem. C 2015, 119, 33−44. (66) Liu, K.; Song, C. L.; Zhou, Y. C.; Zhou, X. Y.; Pan, X. J.; Cao, L. Y.; Zhang, C.; Liu, Y.; Gong, X.; Zhang, H. L. Tuning the Ambipolar Charge Transport Properties of N-Heteropentacenes by Their FrontierMolecular Orbital Energy Levels. J. Mater. Chem. C 2015, 3, 4188−4196. (67) Mohakud, S.; Alex, A. P.; Pati, S. K. Ambipolar Charge Transport in α-Oligofurans: A Theoretical Study. J. Phys. Chem. C 2010, 114, 20436−20442. (68) Chandekar, A.; Whitten, J. E. Ultraviolet Photoemission and Electron Loss Spectroscopy of Oligothiophene Films. Synth. Met. 2005, 150, 259−264. (69) Politzer, P.; Murray, J. S.; Clark, T. Halogen Bonding: An Electrostatically-Driven Highly Directional Noncovalent Interaction. Phys. Chem. Chem. Phys. 2010, 12, 7748−7757. (70) Lee, H.; Yi, Y.; Cho, S. W.; Choi, W. K. Theoretical Investigation on the Electronic and Charge Transport Characteristics of Push-Pull Molecules for Organic Photovoltaic Cells. Synth. Met. 2014, 194, 118−125. (71) Murray, J. S.; Politzer, P. The Electrostatic Potential: An Overview. Wiley Interdiscip. Rev.: Comput. Mol. Sci. 2011, 1, 153−163. (72) Duan, Y. A.; Li, H. B.; Geng, Y.; Wu, Y.; Wang, G. Y.; Su, Z. M. Theoretical Studies on the Hole Transport Property of Tetrathienoarene Derivatives: The Influence of the Position of Sulfur Atom, Substituent and π-Conjugated Core. Org. Electron. 2014, 15, 602−613. (73) Zhang, X. Y.; Zhao, G. J.; Huang, J. D.; Zhang, W. P. Effects of Carbon Chain on Hole-Transport Properties in Naphtho [2, 1-b: 6, 5b′] Difuran Derivatives: Remarkable Anisotropic Mobilities. Org. Electron. 2014, 15, 3341−3348. (74) Wen, S. H.; Deng, W. Q.; Han, K. L. Revealing Quantitative Structure-Activity Relationships of Transport Properties in Acene and Acene Derivative Organic Materials. Phys. Chem. Chem. Phys. 2010, 12, 9267−9275. (75) Ihaka, R.; Gentleman, R. R: A Language for Data Analysis and Graphics. J. Comput. Graph. Stat. 1996, 5, 299−314.

(41) Chen, X. P.; Jiang, J. K.; Liang, Q. H.; Yang, N.; Ye, H. Y.; Cai, M.; Shen, L.; Yang, D. G.; Ren, T. L. First-Principles Study of the Effect of Functional Groups on Polyaniline Backbone. Sci. Rep. 2015, 5, 16907. (42) Chen, X. P.; Liang, Q. H.; Jiang, J. K.; Wong, C. K. Y.; Leung, S. Y. Y.; Ye, H. Y.; Yang, D. G.; Ren, T. L. Functionalization-Induced Changes in the Structural and Physical Properties of Amorphous Polyaniline: A First-Principles and Molecular Dynamics Study. Sci. Rep. 2016, 6, 20621. (43) Shokuhi Rad, A.; Valipour, P. Interaction of Methanol with Some Aniline and Pyrrole Derivatives: DFT Calculations. Synth. Met. 2015, 209, 502−511. (44) Evain, M.; Quillard, S.; Corraze, B.; Wang, W.; MacDiarmid, A. G. A. Phenyl-end-capped Tetramer of Aniline. Acta Crystallogr., Sect. E: Struct. Rep. Online 2002, 58, o343−o344. (45) Deng, W. Q.; Goddard, W. A., III Predictions of Hole Mobilities in Oligoacene Organic Semiconductors from Quantum Mechanical Calculations. J. Phys. Chem. B 2004, 108, 8614−8621. (46) Wen, S. H.; Li, A.; Song, J. L.; Deng, W. Q.; Han, K. L.; Goddard, W. A., III First-Principles Investigation of Anistropic Hole Mobilities in Organic Semiconductors. J. Phys. Chem. B 2009, 113, 8813−8819. (47) Han, K.; Huang, J. D.; Chai, S.; Wen, S. H.; Deng, W. Q.; Han, K. Anisotropic Mobilities in Organic Semiconductors. Nat. Protoc. Exch. 2013, DOI: 10.1038/protex.2013.070. (48) Coropceanu, V.; Cornil, J.; da Silva Filho, D. A.; Olivier, Y.; Silbey, R.; Brédas, J. L. Charge Transport in Organic Semiconductors. Chem. Rev. 2007, 107, 926−952. (49) Marcus, R. A. On the Theory of Oxidation-Reduction Reactions Involving Electron Transfer. J. Chem. Phys. 1956, 24, 966−978. (50) Hush, N. S. Adiabatic Rate Processes at Electrodes. I. EnergyCharge Relationships. J. Chem. Phys. 1958, 28, 962−972. (51) Moon, H.; Zeis, R.; Borkent, E. J.; Besnard, C.; Lovinger, A. J.; Siegrist, T.; Kloc, C.; Bao, Z. N. Synthesis, Crystal Structure, and Transistor Performance of Tetracene Derivatives. J. Am. Chem. Soc. 2004, 126, 15322−15323. (52) Wang, C. L.; Wang, F. H.; Yang, X. D.; Li, Q. K.; Shuai, Z. G. Theoretical Comparative Studies of Charge Mobilities for Molecular Materials: Pet Versus Bnpery. Org. Electron. 2008, 9, 635−640. (53) Kuo, M. Y.; Chen, H. Y.; Chao, I. Cyanation: Providing a Threein-One Advantage for the Design of n-Type Organic Field-Effect Transistors. Chem. - Eur. J. 2007, 13, 4750−4758. (54) Kwiatkowski, J. J.; Nelson, J.; Li, H.; Bredas, J. L.; Wenzel, W.; Lennartz, C. Simulating Charge Transport in Tris (8-hydroxyquinoline) Aluminium (Alq 3). Phys. Chem. Chem. Phys. 2008, 10, 1852− 1858. (55) Yamada, T.; Sato, T.; Tanaka, K.; Kaji, H. Percolation paths for charge transports in N,N′-diphenyl-N,N′-di(m-tolyl) Benzidine (TPD). Org. Electron. 2010, 11, 255−265. (56) Coropceanu, V.; Nakano, T.; Gruhn, N. E.; Kwon, O.; Yade, T.; Katsukawa, K i.; Bredas, J. L. Probing Charge Transport in π-Stacked Fluorene-Based Systems. J. Phys. Chem. B 2006, 110, 9482−9487. (57) Bredas, J. L.; Beljonne, D.; Coropceanu, V.; Cornil, J. ChargeTransfer and Energy-Transfer Processes in π-Conjugated Oligomers and Polymers: A Molecular Picture. Chem. Rev. 2004, 104, 4971− 5004. (58) Hutchison, G. R.; Ratner, M. A.; Marks, T. J. Hopping Transport in Conductive Heterocyclic Oligomers: Reorganization Energies and Substituent Effects. J. Am. Chem. Soc. 2005, 127, 2339− 2350. (59) Varela-Á lvarez, A.; Sordo, J. A.; Scuseria, G. E. Doping of Polyaniline by Acid- Base Chemistry: Density Functional Calculations with Periodic Boundary Conditions. J. Am. Chem. Soc. 2005, 127, 11318−11327. (60) Romanova, J.; Petrova, J.; Ivanova, A.; Tadjer, A.; Gospodinova, N. Theoretical study on the emeraldine salt-impact of the computational protocol. J. Mol. Struct.: THEOCHEM 2010, 954, 36−44. (61) Petrova, J. N.; Romanova, J. R.; Madjarova, G. K.; Ivanova, A. N.; Tadjer, A. V. Fully Doped Oligomers of Emeraldine Salt: Polaronic H

DOI: 10.1021/acs.jpcc.7b04942 J. Phys. Chem. C XXXX, XXX, XXX−XXX