Letter Cite This: J. Phys. Chem. Lett. 2019, 10, 3376−3380
pubs.acs.org/JPCL
Impact of Stoichiometry and Fluorine Atoms on the Charge Transport of Perylene−F4TCNQ Yishan Wang,† Chengzhi Zheng,‡ Wei Hao,§ Hu Zhao,∥ Shuzhou Li,§ Lin Shen,† Jia Zhu,*,† and Chong-An Di‡
Downloaded via NOTTINGHAM TRENT UNIV on August 13, 2019 at 10:50:17 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
†
College of Chemistry, Key Laboratory of Theoretical & Computational Photochemistry of Ministry of Education, Beijing Normal University, Beijing 100875, P. R. China ‡ Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China § School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore ∥ Department of Physics, Beijing Normal University, Beijing 100875, P. R. China S Supporting Information *
ABSTRACT: The charge-transport properties of charge-transfer complexes (CTCs) play a key role in the potential applications toward novel optoelectronic devices. We have systematically studied the charge-transport properties of perylene−F4TCNQ CTCs with different stoichiometric ratios by first-principles calculations. Our calculated results showed that 1P1F4 (perylene−F4TCNQ 1:1) exhibits a higher charge-carrier mobility than 3P2F4 (perylene−F4TCNQ 3:2) due to the strong interlayer interactions in 3P2F4. Compared with the perylene−TCNQ CTC, the higher charge-carrier mobility in perylene−F4TCNQ CTC indicates that introducing fluorine atoms can enhance the charge-carrier mobility due to stronger intermolecular interactions. More importantly, the experimental measurements carried out with 1P1F4- and 3P2F4-based field-effect transistors are consistent with the theoretical predictions. Our study reveals that tuning the charge-transport properties in CTCs by controlling the stoichiometry between the donor and acceptor is a promising strategy in accelerating the development of high-performance organic electronic materials. rganic field-effect transistors (OFETs) have broad application prospects in the next generation of organic circuits such as radio-frequency identification (RFID) tags, smart cards, and organic active matrix displays.1−5 As the key element in an OFET, high-mobility organic semiconductors have received focused attention in the past three decades. Although many p-type semiconductors with prominent chargetransport properties have been widely studied, the development of n-type and ambipolar materials with good stability and high mobility is still far from satisfactory. Because of the unique feature of tunable molecular energy levels, charge-transfer complexes (CTCs) have become promising candidates for high-performance n-type and even ambipolar devices.6,7 Ideally, the incorporation of donor and acceptor molecules into one material by cocrystallization can manipulate the charge-transport properties in a facile approach. As a clear example, Zhang et al. found that 2,7-di-tert-butyl-10,14di(thiophen-2-yl)phenanthro[4,5-abc][1,2,5]thiadiazolo[3,4i]phenazine (DTPTP) could be switched from a typical p-type semiconductor to an n-type semiconductor through tetracyanoquinodimethane (TCNQ) doping.8 More interestingly, Zhu et al. first reported meso-diphenyl tetrathia[22]annulene[2,1,2,1] DPTTA-TCNQ based ambipolar OFETs with mobility of 0.04 cm2 V−1 s−1 for holes and 0.03 cm2 V−1 s−1 for electrons, respectively.9 Despite these achievements, CTCs
O
© 2019 American Chemical Society
still suffer from relatively lower mobility than that of singlecomponent materials, which greatly limits their application in high-performance OFETs.10 Hence the design of high-mobility CTCs requires an in-depth study of the relationship between the molecular structure and the charge-transport property at the molecular level. Fine-tuning the donor (D) and acceptor (A) is a powerful strategy to manipulate the electric properties of CTCs, which is indicated by increased mobility and obviously enhanced electrical conductivity along with changed donors and fluorine atoms introduced to the lower lowest unoccupied molecular orbital (LUMO) energy level of acceptors.9,11−18 The influence of stoichiometry is also an important factor to affect charge transport but is often overlooked. In this regard, CTCs based on perylene and Fx TCNQ (TCNQ = 7,7,8,8tetracyanoquinodimethane; x = 0, 1, 2, 4) have aroused broad interest due to their excellent π-conjugated structures. By increasing the number of fluorine atoms to reduce the acceptor LUMO energy level from −4.23 (TCNQ) to −5.24 eV (F4TCNQ)19 or changing the stoichiometric ratio between the donor and acceptor, the electronic properties of CTC can Received: May 6, 2019 Accepted: June 3, 2019 Published: June 3, 2019 3376
DOI: 10.1021/acs.jpclett.9b01299 J. Phys. Chem. Lett. 2019, 10, 3376−3380
Letter
The Journal of Physical Chemistry Letters
axis as α-layer and molecules with a −DADDAD−-oriented c axis as γ-layer. Therefore, different layers dominate the charge transport in distinct directions, and we can further study the interaction between layers and the charge-transport properties in these two layers. Moreover, the mean distances between the adjacent donor and acceptor layers in these two kinds of packing motifs of 3P2F4 are 3.21 and 3.06 Å, respectively, which indicates that tailoring the stoichiometric ratio between the donor and acceptor can change the packing mode and thus slightly tune the distance between molecular layers. Large valence band (VB) or conduction band (CB) width is the characteristic of high hole or electron mobility. Hence, band structures of 1P1F4 and 3P2F4 are calculated (Figure S1). In 1P1F4, VB and CB are almost equally dispersive with large bandwidths of 512 and 461 meV, respectively. This quasimirror symmetry suggests that the transfer capacity for holes and electrons is expected to be comparable.13,22,23 By contrast, the band structure of 3P2F4 exhibits asymmetric images due to its herringbone packing model with two alternating stacks. The CB width is 389 meV, which is greatly larger than the VB width of 156 meV, suggesting that 3P2F4 is more expected to exhibit the n-type transport property. Comparing 3P2F4 and 1P1F4, bandwidths of VB and CB in 3P2F4 are much smaller than those in 1P1F4, which means the charge-carrier mobility of 3P2F4 is lower. Charge-carrier mobility can also be evaluated by the results of effective masses.24,25 Table 1 shows that 1P1F4 has smaller hole and electron effective masses along the stacking direction, which suggests more excellent charge-carrier mobility. Besides, the effective masses of holes and electrons of 1P1F4 are comparable, which agrees with the band structure results, but in the case of 3P2F4, the hole effective mass along the stacking direction is significantly heavier than that of the electron, which leads to a lower hole mobility. In addition, we can also find that the hole transport of 3P2F4 exhibits 1D whereas others exhibit 2D transport properties. To analyze the interaction between perpendicular stacks of 3P2F4, its isolated-layer band structures are considered, as shown in Figure 2. Bands from the α-layer are colored red, and those from γ-layer are colored blue. Isolated-layer band structures overlay on the full 3P2F4 complex band structure (colored gray). First, by analyzing band shapes between isolated layers and the full 3P2F4 crystal, we can find that the CB of the α-layer (red 1) is similar to that of 3P2F4 crystal (gray 1), whereas the VB of the γ-layer (blue 2) is similar to that of 3P2F4 crystal (gray 2). Therefore, we can conclude that the CB and VB of 3P2F4 come from the α-layer and γ-layer, respectively. Hence, the α-layer mainly controls the electron
be easily modulated.20,21 Although the critical role of the stoichiometric ratio and fluorine atoms in affecting the chargetransfer degree of this family of materials has been previously investigated,16 the influence of these two factors on the chargecarrier mobility is not well understood. In this work, we chose perylene−F4TCNQ CTCs with 1:1 (1P1F4) and 3:2 (3P2F4) ratios to study the influence of stoichiometry on their chargetransport properties. In addition, the influence of fluorine atoms on the charge-transport of this material is also considered by comparing to their performance with that of perylene−TCNQ. Both 1P1F4 crystal and 3P2F4 crystal are grown by the Htube solution process, where F4TCNQ and perylene were dissolved in acetonitrile and placed at two opposite sides of an H tube, respectively (Figure 1, left). The experimental details
Figure 1. Left: Schematic illustration of the crystal growth process of H-tube solution CTCs. Middle and right: Crystal morphology and crystal packing of (top) 1P1F4 and (bottom) 3P2F4..
can be found in the Supporting Information. The crystal morphology and crystal packing are also diagrammed in Figure 1. Both 1P1F4 and 3P2F4 exhibit a mixed-stack mode in stacking directions. 1P1F4 shows a layer-by-layer packing motif and stacks along the a axis with −DADA−. The mean distance between the adjacent donor and acceptor layers is 3.12 Å. In the case of 3P2F4, the crystal exhibits a herringbone-packing model that has two perpendicular stacking directions: One is stacking with −DADA− along the a axis; another is stacking with −DADDAD− along the c axis. In this regard, an alternating layered structure stacking along the b axis can be described. We defined molecules with a −DADA−-oriented a
Table 1. Effective Masses for Hole (mh) and Electron (me) at the Valence Band and Conduction Band Edges of Perylene− F4TCNQa hole mh/m0 1P1F4
3P2F4
0.283 2.829 18.97 1.549 12.37 143.5
electron parallel to
a− b+ c+ a− c− b−
0.0072b 0.1014a 0.2805a 0.0011b 0.3414a 0.3910a
+ 0.0248c + 0.0100c + 0.3622b + 0.0536c − 0.4518b + 0.1126c
me/m0
parallel to
0.259 3.105 5.853 0.274 2.542 17.56
a − 0.0486b − 0.0180c b + 0.2440a + 0.5239c −0.9641c + b − 0.2905a a − 0.0126b + 0.0058c c + 0.0082a − 0.1750b b − 0.2379a − 0.0745c
a
m0 represents the free-electron rest mass. m in bold means that the effective mass is small, so the corresponding direction allows significant charge transport. 3377
DOI: 10.1021/acs.jpclett.9b01299 J. Phys. Chem. Lett. 2019, 10, 3376−3380
Letter
The Journal of Physical Chemistry Letters
larger than those of the isolated-layer (0.472m0), but the electron effective mass of full 3P2F4 is smaller (0.274m0 compared with 0.455m0). This reveals that the interaction between layers makes the transport of holes less active but promotes the transport of electrons. As can be seen, the interaction between layers in this orthometric packing model would play an important role in charge transport. The analysis of electronic couplings (t) for important charge-transport pathways contributes to the understanding of the intrinsic interaction between molecules. It can also help us explain the results of band structures and effective masses from a more microscopic perspective. In mixed-stack CTCs, the electronic couplings come from contributions of the superexchange mechanism (tSE) and direct interactions (td).26,27 The calculated results are listed in Tables S1 and S2, and the involved molecules are shown in Figure 3. For 1P1F4 in Figure
Figure 2. Band structures of α-layer (red) and γ-layer (blue) overlay on the full 3P2F4 band structure (gray). The zero of energy is given at the Fermi energy. The points of high symmetry in the first Brillouin zone are labeled as the Figure S1 caption shows.
transport and the γ-layer controls the hole transport. The αlayer also contributes to VB-2, whereas the γ-layer contributes to VB-1 and CB-1. Additionally, the VB and CB of the α-layer almost exhibit an equal dispersion, but the CB of the γ-layer is very flat. By comparing the difference between isolated-layer and full 3P2F4 band structures, we found that the band gap of the full complex is smaller than the gap between the isolatedlayer CB (red 1) and VB (blue 2), which implies significant interactions between two layers. Interestingly, considering the shift of isolated-layer bands, the CB from the α-layer (red 1) is almost consistent with the CB of the full 3P2F4 (gray 1), but the VB from the γ-layer (blue 2) obviously shifts compared with gray band 2, which reveals that the interaction between layers has a greater impact on the transport of holes. As a result, it is the γ-layer that mainly contributed to the VB of full 3P2F4, but the position of the VB of the isolated α-layer (red 3) is higher than that of the γ-layer. This means that the hole mobility in the α-layer should have been stronger but was limited by the interaction between layers. The isolated-layer effective masses listed in Table 2 benefit our understanding of this point. In the first place, smaller hole and electron effective masses of the α-layer suggest that the layer-by-layer packing motif of the α-layer with a particular overlap can allow more efficient charge transport. Next, removing another layer is beneficial for crystals to exhibit an ambipolar charge-transport property: In the 3P2F4, the electron effective mass is smaller than hole effective mass by a factor of ∼6, but after the removal of the γlayer, the hole and electron effective masses are nearly equal. More importantly, we found that the interaction between layers has an opposite effect on the transport of holes and electrons; the interaction between layers can weaken the hole transport along the stacking direction but facilitate the electron transport. It can be concluded by the results that hole effective masses of full 3P2F4 along the stacking direction (1.549m0) are
Figure 3. Most important transport pairs of the (a) hole and (b) electron of 1P1F4 and (c) hole and (d) electron of 3P2F4. In 3P2F4, molecules in the α-layer are red and molecules in the γ-layer are blue.
3a,b, tSE is along the stacking direction (pair 12), whereas td is generated between two adjacent molecules belonging to different stacks (pairs 13 and 14). Intrastack tSE values of electrons and holes are comparable, which leads to a quasimirror-symmetric band structure as well as almost equal hole and electron effective masses. The largest tSE indicates that the stacking direction is the most dominant transport channel. In addition, significant interstack electronic coupling (pair 14) helps 1P1F4 exhibit 2D hole- and electron-transport properties, which agree with the results of effective masses. For 3P2F4 in Figure 3c,d, electronic couplings of the α-layer, γ-layer, and interlayer pathways are considered, respectively. Interlayer electronic couplings can help us to evaluate the impact of the interaction between layers on the charge
Table 2. Effective Masses for Hole (mh) and Electron (me) at the Valence Band and Conduction Band Edges in Isolated Layers of 3P2F4a α-layer γ-layer
mh/m0
parallel to
me/m0
parallel to
0.472 8.410 1.514 19.73
a − 0.0006b − 0.0004c c + 0.0098a − 0.0175b a + 0.0010b + 0.0760c c − 0.7577a + 0.0722b
0.455 2.767 7.839 17.11
a − 0.0003b − 0.0035c c + 0.0313a + 0.0062b c + 0.5987a − 0.0021b a − 0.0084b − 0.0612c
a
m0 represents the free-electron rest mass. Only the two smallest effective masses are listed in the table. 3378
DOI: 10.1021/acs.jpclett.9b01299 J. Phys. Chem. Lett. 2019, 10, 3376−3380
Letter
The Journal of Physical Chemistry Letters transport of 3P2F4. tSE values of holes and electrons in the αlayer (pair 12) are almost equal, whereas there is a certain gap in the γ-layer (pair 45), in agreement with isolated-layer band structure and effective mass results. Except for pairs 12, 45, and 89, the rest of the molecular pairs correspond to direct electronic couplings for interstack pathways. Considering hole electronic couplings in the α-layer and γ-layer, significant values can be found not only along stacking directions but also along interstack pathways (pairs 56, 57, and 58), but electrons only have one effective direct electronic coupling along the pair 47 direction. Besides, when it comes to direct electronic couplings of interlayer pathways, there are more significant interlayer electronic couplings of holes than those of electrons. Hence these interstack and interlayer hole electronic couplings are the most possible reasons that lead to the flat VB shape and large hole effective mass of 3P2F4. Furthermore, the significant interlayer electronic couplings of holes that suggest a strong interaction between layers ultimately have a negative influence on the hole transport along the stacking directions of 3P2F4. To explore the impact of fluorine atoms on the charge transport of perylene−F4TCNQ, the charge-transport parameters of perylene−TCNQ with 1:1 (1P1F0) and 3:1 (3P1F0) stoichiometry were calculated (Part 3 in the Supporting Information). The results indicate that the incorporation of fluorine atoms facilitates a stronger tSE of hole and electron, larger VB and CB width, and smaller hole and electron effective masses. Thus we can conclude that the charge transport of perylene−F4TCNQ is more efficient than that of perylene−TCNQ. Furthermore, comparing 1P1F0 and 3P1F0, 1P1F0 exhibits a larger band dispersion and smaller effective masses, suggesting that 1:1 stoichiometry with layer-by-layer packing mode contributes to charge transport, which agrees with the conclusions mentioned above. To verify our theoretical predictions, OFETs based on 1P1F4 and 3P2F4 were fabricated for the mobility measurement. The experimental details are in Part 4 of the Supporting Information. The FET based on 1P1F4 and 3P2F4 exhibits n-type semiconducting behavior with electron mobilities of 0.171 and 0.083 cm2 V−1 s−1, respectively, which are higher than those of devices with 1P1F0 and 3P1F0.20 Besides, the chargecarrier mobility of the FET with 1P1F4 is larger than that with 3P2F4. Both theoretical and experimental results indicate that studied 1:1 CTCs with a layer-by-layer packing motif and fluorinated acceptor conduce to higher mobility. However, the FET with 1P1F4 does not exhibit an ambipolar chargetransport property. The absence of p-type behavior may result from the deep and shallow trap states in crystals.20,22 To summarize, we found that the stoichiometry has a great influence on the molecular packing mode, thereby affecting the charge-transport properties. The layer-by-layer packing motif is expected with 1:1 stoichiometry, but when the ratio of donor and acceptor is unequal, the complex tends to exhibit a herringbone stacking mode, which exhibits different chargetransport layers. The interaction between layers plays an important role in the charge transport. In our work, theoretical and experimental results suggest that 1P1F4 and 1P1F0 with a layer-by-layer motif exhibit a higher transport efficiency than 3P2F4 and 3P1F0 with a herringbone motif. More importantly, in 3P2F4, the interaction between perpendicular stacks can reduce the hole transport but facilitate electron transport along the stacking directions due to interstack and interlayer electronic couplings. Additionally, the incorporation of fluorine atoms helps to strengthen superexchange electronic couplings,
enlarge bandwidths, and reduce effective masses, thus leading to high mobility. Our results provide an excellent example to show that the charge-transport properties of CTCs can be promoted by introducing fluorine atoms and tailoring the stoichiometric ratio between the donor and acceptor. Moreover, there are still some worthy studies in the field of CTCs, such as the role of the charge-transfer degree and radicals caused by charge transfer in affecting the mobility, that require further efforts to solve and thus contribute to obtaining highperformance OFETs.
■
COMPUTATIONAL METHODS The lattice optimization and band-structure calculations were performed by using the vdW-DF2 exchange-correlation functional28,29 and projector-augmented wave (PAW) basis sets in VASP 5.3 code.30 The cutoff energy of the planewave was 450 eV. The Monkhorst−Pack scheme was selected to generate k meshes. The convergence criterion of the total energy was set to 10−5 eV in the self-consistent field loop. The experimental methods of crystal growth and mobility measurement are provided in the Supporting Information.
■
ASSOCIATED CONTENT
* Supporting Information S
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpclett.9b01299. Computational methods; details of additional DFT results, including calculated electronic couplings of perylene−F4TCNQ and charge-transport parameters of perylene−TCNQ; and experimental details (PDF)
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Shuzhou Li: 0000-0002-2159-2602 Jia Zhu: 0000-0002-4938-2850 Chong-An Di: 0000-0002-6183-1321 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS We are grateful to Prof. Zhigang Shuai, Prof. Yuanping Yi and Prof. Hua Geng for providing helpful ideas and thoughts about the computation. This work was supported by the National Natural Science Foundation of China, grant no. 21773016 and the Ministry of Education Singapore (Tier 1 RG104/18).
■
REFERENCES
(1) Dimitrakopoulos, C. D.; Malenfant, P. R. L. Organic Thin Film Transistors for Large Area Electronics. Adv. Mater. 2002, 14, 99−117. (2) Tsao, H. N.; Cho, D. M.; Park, I.; Hansen, M. R.; Mavrinskiy, A.; Yoon, D. Y.; Graf, R.; Pisula, W.; Spiess, H. W.; Müllen, K. Ultrahigh Mobility in Polymer Field-Effect Transistors by Design. J. Am. Chem. Soc. 2011, 133, 2605−2612. (3) Baude, P. F.; Ender, D. A.; Haase, M. A.; Kelley, T. W.; Muyres, D. V.; Theiss, S. D. Pentacene-Based Radio-Frequency Identification Circuitry. Appl. Phys. Lett. 2003, 82, 3964−3966. (4) Huitema, H. E. A.; Gelinck, G. H.; van der Putten, J. B. P. H.; Kuijk, K. E.; Hart, C. M.; Cantatore, E.; Herwig, P. T.; van Breemen,
3379
DOI: 10.1021/acs.jpclett.9b01299 J. Phys. Chem. Lett. 2019, 10, 3376−3380
Letter
The Journal of Physical Chemistry Letters A. J. J. M.; de Leeuw, D. M. Plastic Transistors in Active-Matrix Displays. Nature 2001, 414, 599−599. (5) Sheraw, C. D.; Zhou, L.; Huang, J. R.; Gundlach, D. J.; Jackson, T. N.; Kane, M. G.; Hill, I. G.; Hammond, M. S.; Campi, J.; Greening, B. K.; Francl, J.; West, J. Organic Thin-Film Transistor-Driven Polymer-Dispersed Liquid Crystal Displays on Flexible Polymeric Substrates. Appl. Phys. Lett. 2002, 80, 1088−1090. (6) Zhang, J.; Jin, J.; Xu, H.; Zhang, Q.; Huang, W. Recent Progress on Organic Donor−Acceptor Complexes as Active Elements in Organic Field-Effect Transistors. J. Mater. Chem. C 2018, 6, 3485− 3498. (7) Sato, R.; Dogishi, M.; Higashino, T.; Kadoya, T.; Kawamoto, T.; Mori, T. Charge-Transfer Complexes of Benzothienobenzothiophene with Tetracyanoquinodimethane and the N-Channel Organic FieldEffect Transistors. J. Phys. Chem. C 2017, 121, 6561−6568. (8) Zhang, J.; Gu, P.; Long, G.; Ganguly, R.; Li, Y.; Aratani, N.; Yamada, H.; Zhang, Q. Switching Charge-Transfer Characteristics from P-Type to N-Type through Molecular “Doping” (CoCrystallization). Chem. Sci. 2016, 7, 3851−3856. (9) Zhang, J.; Geng, H.; Virk, T. S.; Zhao, Y.; Tan, J.; Di, C. A.; Xu, W.; Singh, K.; Hu, W.; Shuai, Z.; Liu, Y.; Zhu, D. Sulfur-Bridged Annulene-TCNQ Co-Crystal: A Self-Assembled ’’Molecular Level Heterojunction’’ with Air Stable Ambipolar Charge Transport Behavior. Adv. Mater. 2012, 24, 2603−2607. (10) Zhang, J.; Xu, W.; Sheng, P.; Zhao, G.; Zhu, D. Organic DonorAcceptor Complexes as Novel Organic Semiconductors. Acc. Chem. Res. 2017, 50, 1654−1662. (11) Dobrowolski, M. A.; Garbarino, G.; Mezouar, M.; Ciesielski, A.; Cyrański, M. K. Structural Diversities of Charge Transfer Organic Complexes. Focus on Benzenoid Hydrocarbons and 7,7,8,8Tetracyanoquinodimethane. CrystEngComm 2014, 16, 415−429. (12) Yang, C.-Y.; Jin, W.-L.; Wang, J.; Ding, Y.-F.; Nong, S.; Shi, K.; Lu, Y.; Dai, Y.-Z.; Zhuang, F.-D.; Lei, T.; Di, C.-A.; Zhu, D.; Wang, J.Y.; Pei, J. Enhancing the N-Type Conductivity and Thermoelectric Performance of Donor−Acceptor Copolymers through Donor Engineering. Adv. Mater. 2018, 30, 1802850. (13) Qin, Y.; Cheng, C.; Geng, H.; Wang, C.; Hu, W.; Xu, W.; Shuai, Z.; Zhu, D. Efficient Ambipolar Transport Properties in Alternate Stacking Donor-Acceptor Complexes: From Experiment to Theory. Phys. Chem. Chem. Phys. 2016, 18, 14094−14103. (14) Wu, H.-D.; Wang, F.-X.; Zhang, M.; Pan, G.-B. Investigation of Transport Properties of Coronene·TCNQ Cocrystal Microrods with Coronene Microrods and TCNQ Microsheets. Nanoscale 2015, 7, 12839−12842. (15) Zhang, J.; Liu, G.; Zhou, Y.; Long, G.; Gu, P.; Zhang, Q. Solvent Accommodation: Functionalities Can Be Tailored through Co-Crystallization Based on 1:1 Coronene-F4TCNQ Charge-Transfer Complex. ACS Appl. Mater. Interfaces 2017, 9, 1183−1188. (16) Jiang, H.; Hu, P.; Ye, J.; Zhang, K. K.; Long, Y.; Hu, W.; Kloc, C. Tuning of the Degree of Charge Transfer and the Electronic Properties in Organic Binary Compounds by Crystal Engineering: A Perspective. J. Mater. Chem. C 2018, 6, 1884−1902. (17) Iijima, K.; Sanada, R.; Yoo, D.; Sato, R.; Kawamoto, T.; Mori, T. Carrier Charge Polarity in Mixed-Stack Charge-Transfer Crystals Containing Dithienobenzodithiophene. ACS Appl. Mater. Interfaces 2018, 10, 10262−10269. (18) Yang, Y.; Liu, G.; Liu, J.; Wei, M.; Wang, Z.; Hao, X.; Maheswar Repaka, D. V.; Ramanujan, R. V.; Tao, X.; Qin, W.; Zhang, Q. Anisotropic Magnetoelectric Coupling and Cotton−Mouton Effects in the Organic Magnetic Charge-Transfer Complex Pyrene− F4TCNQ. ACS Appl. Mater. Interfaces 2018, 10, 44654−44659. (19) Hu, P.; Du, K.; Wei, F.; Jiang, H.; Kloc, C. Crystal Growth, Homo−Lumo Engineering, and Charge Transfer Degree in PeryleneFxTCNQ (X = 1, 2, 4) Organic Charge Transfer Binary Compounds. Cryst. Growth Des. 2016, 16, 3019−3027. (20) Zhu, W.; Yi, Y.; Zhen, Y.; Hu, W. Precisely Tailoring the Stoichiometric Stacking of Perylene-TCNQ Co-Crystals Towards Different Nano and Microstructures with Varied Optoelectronic Performances. Small 2015, 11, 2150−2156.
(21) Salzillo, T.; Masino, M.; Kociok-Köhn, G.; Di Nuzzo, D.; Venuti, E.; Della Valle, R. G.; Vanossi, D.; Fontanesi, C.; Girlando, A.; Brillante, A.; Da Como, E. Structure, Stoichiometry, and Charge Transfer in Cocrystals of Perylene with TCNQ-Fx. Cryst. Growth Des. 2016, 16, 3028−3036. (22) Shokaryev, I.; Buurma, A. J. C.; Jurchescu, O. D.; Uijttewaal, M. A.; de Wijs, G. A.; Palstra, T. T. M.; de Groot, R. A. Electronic Band Structure of Tetracene−TCNQ and Perylene−TCNQ Compounds. J. Phys. Chem. A 2008, 112, 2497−2502. (23) Vermeulen, D.; Zhu, L. Y.; Goetz, K. P.; Hu, P.; Jiang, H.; Day, C. S.; Jurchescu, O. D.; Coropceanu, V.; Kloc, C.; McNeil, L. E. Charge Transport Properties of Perylene−TCNQ Crystals: The Effect of Stoichiometry. J. Phys. Chem. C 2014, 118, 24688−24696. (24) Zhu, L.; Coropceanu, V.; Yi, Y.; Chilukuri, B.; Cundari, T. R.; Brédas, J.-L. Electronic and Charge-Transport Properties of the Au3(CH3N = COCH3)3 Crystal: A Density Functional Theory Study. J. Phys. Chem. Lett. 2013, 4, 2186−2189. (25) Ai, Q.; Getmanenko, Y. A.; Jarolimek, K.; Castaneda, R.; Timofeeva, T. V.; Risko, C. Unusual Electronic Structure of the Donor-Acceptor Cocrystal Formed by Dithieno[3,2-A:2’,3′-C]Phenazine and 7,7,8,8-Tetracyanoquinodimethane. J. Phys. Chem. Lett. 2017, 8, 4510−4515. (26) Zhu, L.; Yi, Y.; Li, Y.; Kim, E. G.; Coropceanu, V.; Bredas, J. L. Prediction of Remarkable Ambipolar Charge-Transport Characteristics in Organic Mixed-Stack Charge-Transfer Crystals. J. Am. Chem. Soc. 2012, 134, 2340−2347. (27) Geng, H.; Zheng, X.; Shuai, Z.; Zhu, L.; Yi, Y. Understanding the Charge Transport and Polarities in Organic Donor−Acceptor Mixed-Stack Crystals: Molecular Insights from the Super-Exchange Couplings. Adv. Mater. 2015, 27, 1443−1449. (28) Lee, K.; Murray, É . D.; Kong, L.; Lundqvist, B. I.; Langreth, D. C. Higher-Accuracy Van Der Waals Density Functional. Phys. Rev. B: Condens. Matter Mater. Phys. 2010, 82, 081101. (29) Klimeš, J.; Bowler, D. R.; Michaelides, A. Van Der Waals Density Functionals Applied to Solids. Phys. Rev. B: Condens. Matter Mater. Phys. 2011, 83, 195131. (30) Kresse, G.; Furthmüller, J. Efficiency of Ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Comput. Mater. Sci. 1996, 6, 15−50.
3380
DOI: 10.1021/acs.jpclett.9b01299 J. Phys. Chem. Lett. 2019, 10, 3376−3380
