Second-Order Nonlinear Optical Switch Manipulation of

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A: Kinetics, Dynamics, Photochemistry, and Excited States

Second-Order Nonlinear Optical Switch Manipulation of Photosensitive Layer by an External Electric Field Coupled with Graphene Quantum Dots Xiaofei Wang, Yuanzuo Li, Peng Song, Feng-Cai Ma, and Yanhui Yang J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.9b05249 • Publication Date (Web): 01 Aug 2019 Downloaded from pubs.acs.org on August 5, 2019

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The Journal of Physical Chemistry

Second-Order Nonlinear Optical Switch Manipulation of Photosensitive Layer by an External Electric Field Coupled with Graphene Quantum Dots

Xiaofei Wang,[a] Yuanzuo Li,*[a] Peng Song,[b] Fengcai Ma,[b] Yanhui Yang,*[c] aCollege

of Science, Northeast Forestry University, Harbin 150040, Heilongjiang, China; bDepartment of Physics, Liaoning University Shenyang 110036, Liaoning, China; c Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, 211816 Nanjing, China;

-----------------------------------Corresponding author: Tel.: +86 451 82192245 8211; E-mail: [email protected], [email protected]

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The Journal of Physical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract The main purpose of this work is to explore the effect of graphene quantum dots (GR) filling the photosensitive layer. The Multi-branches dye JH-1 as the photoactive layer material was used to analyze the non-negligible role of graphene quantum dots from the perspectives of optimized structure, electrochemical parameters, optical properties, non-linear optical (NLO) switch and external electric field. The results demonstrated that the graphene quantum dots not only improve the optical properties of solar cells, but also control the electron transfer in the photosensitive layer molecules under the manipulation of a specific external electric field. When the external electric field intensity is below 20 × 10-4 au, the excess electron orbital does not change. When the external electric field reaches 25 × 10-4 au, the excess electron orbital on the graphene quantum dots crop up response. This discovery allows the electrons transfer from the photosensitive layer, which should be controlled by the NLO switch. In addition, the optical properties of sensitizers showed regular evolution in the external electric field, which provides an effective way to improve the performance. Comprehensive analysis indicated that the doping of graphene quantum dots with the photosensitive layer can be used as a new alternative way to improve the photoelectric conversion efficiency of solar cells.


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1. Introduction A dye-sensitized solar cell (DSSC) has become one of the most popular solar cells in the world, and its performance has been continuously improved in the past few decades because of its low cost and the wide variety of molecules that can be used as dyes, so it has unlimited development potential.1-4 A typical DSSC must have the following components: conductive glass, dye adsorbed TiO2 nanocrystalline film, electrolyte between the poles and Pt counter electrode set.5-8 The wide band gap of TiO2 nanocrystalline film (3.2eV) result in the fact that visible light cannot directly make it respond. After adsorbing a layer of dyes on the surface, the sensitizers can absorb sunlight and generate electrons transfer. Since the excited state energy levels of dyes are higher than that of conduction band edge, electrons can be rapidly injected into the semiconductor.9-11 The electrons are enriched on the conduction band substrate and then flow to the counter electrode through the external circuit. The dye outputs electrons to the semiconductor and then becomes an oxidation state, which is then reduced by I- in the electrolyte to realize dye regeneration. The oxidized electrolyte (I3-) is replenished with electrons on the Pt counter electrode to complete a photoelectric chemical reaction cycle. It can be seen from above principle that the sensitizer is connected with each electron transfer process; so the characteristics of the sensitizer have a crucial influence on the photoelectric performance of DSSC. At present, researchers have carried out extensive research and development on high-performance sensitizers and found that the configuration of sensitizers can directly affect the performance of DSSC.12-14 In the course of constant explorations, sensitizers with D-π-A structure had the characteristics of high performance. Based on this structure, a series of sensitizers of similar configurations were developed, such as D-A-π-A type and D-D-π-A type. Carella et al.15 synthesized three carbazole-based sensitizers with different receptor groups and D-π-A type, and the results showed that using malononitrile as the molecular acceptor group could provide the strongest of hole injection capacity for DSSC, which was more conducive to the photoelectric conversion efficiency (PCE) performance. Xu and his cooperators16 synthesized abenzothiadiazole sensitizer with D-π-A type, and its photoelectric conversion efficiency reached about 8.7%. By doping silicon oxide in the semiconductor substrate and making the 3D inverse opal structure with mesoporous structure, its photoelectric conversion efficiency was improved to about 10.3%. It can be seen that after years of development, the research focus of DSSC has shifted from sensitizer materials to semiconductor substrates and counter electrode (CE), etc. in order to



maximize the performance of DSSC. Areerob and his co-workers17 synthesized a graphene-La6W2O15 doped NiCoSe quantum dot nanosheet as the counter electrode of the device. The results of electrochemical impedance showed that the nanosheet had excellent electrocatalytic properties and low resistance to charge transfer at the interface. In addition to the research breakthrough in the experimental aspect, the theoretical calculation of quantum chemistry has also been deeply explored.18-25 Recently, Xie et al.26 simulated the photochemical and photophysical parameters of two sensitizers with different bridging parts by theoretical means, and found that the structure of the bridging part between the electron donor and the π-spacer had a great influence on the performance of the sensitizer, and the bridging part with a coplanar structure was more beneficial to the optical performance of DSSC. He and collaborators27 used Zn-porphyrin as a building block to explore the effect of Zn-porphyrin' insertion position on the performance of sensitizer, and the results showed that Zn-porphyrin close to the acceptor group was more conducive to the electron transfer of DSSC, and could significantly increase the short-circuit current density. Song et al.28 modified the molecular donor, acceptor and porphyrin core parts to improve the performance of porphyrin-based sensitizer, and the results showed that the insertion of alkyl chain or bulky units could effectively inhibit the rigidity-induced π-π aggregation, thus achieving the effect of improving the performance of DSSC. In this work, based on the research work of Kimand his co-workers,29 the optical properties and electrochemical parameters of the sensitizer JH-1were simulated by quantum chemistry method. In addition, the hybridization of graphene quantum dots was also introduced into the DSSC model to explore the important role of graphene quantum dots in electrons transfer and nonlinear optics (NLO). We also deeply analyzed the effects of graphene quantum dots on electrons transfer and incident light absorption in the external electric field, and introduced the concept of the non-linear optical switch of sensitizer. The microscopic control of the optical properties of sensitizer by the electric field was described by the linear fitting. 2. Computational Details Electronic structure optimization of sensitizer and its hybridization of graphene quantum dot were obtained at the B3LYP/6-31G(d) level using DFT.30-34 The detailed data of ground state and excited state sensitizers molecular orbitals were simulated by Gaussian series software35 and then processed by Multiwfn36 VMD37 program. In order to make the results of theoretical simulation convincing, five representative


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different

functionals

(M062X,

Cam-B3LYP,

PBEPBE,

ωB97X,

and

MPW1PW91)38-42 were used to perform TDDFT43 calculation on the optical properties of sensitizer, so as to screen out which functional is the most successful fitting of the experimental UV-Visible spectrum. It can be seen from the data in Table 1 that the result simulated by ωB97X is the closest value to the experimental spectra. Therefore, the functional ωB97X can be used for the subsequent calculation of the parameters of the excited state. 3. Results and Discussion 3.1. Geometrical Structures The sensitizer and its hybridization of graphene quantum dots (GR) complex are fully optimized in ethanol solution without any structural constraints. The cir-coronene graphene quantum dots with planar reticular structures have been extensively investigated for their excellent electron transport properties and ability to inhibit intramolecular charge recombination.44 The optimized electronic structure of JH-1 is available in Figure 1. Molecular donor part is triphenylamine (TPA), and the π-bridge

section

is

composed

of

the

symmetry

of

2,5-di(thiophen-2-yl)thieno[3,2-b]thiophene (DTT), and molecular acceptor moiety is traditional cyanoacrylic acid group (CAA). In addition, the linked part between the rings was explored, and the microscopic deformation of dihedral angle caused by the doping of quantum dot was discussed, and relevant data were collected in Table 2. The interfacial angles (𝜃1) between the donor portion and π-conjugation of JH-1 and JH-1/GR are 39.57° and 41.22° respectively, which means that the donor portion of the sensitizer was further distorted by cir-coronene graphene quantum dot, and it was more conducive to inhibiting intermolecular rigidity-induced π-π aggregation. The twisted angles 𝜃2 and 𝜃3 in π-conjugation increased slightly after anchoring the quantum dot. Although the linear π-conjugation part is more conducive to electron transport, the increase of the dihedral angle also promotes intermolecular π-π aggregation, both of which cannot be ignored. The dihedral angle (𝜃4) between the π-bridge region and the acceptor group becomes smaller after the graphene is anchored, which helps to reduce the resistance of electron transfer. In addition, the stability of graphene quantum dot for anchored dye system was investigated by analysis of bond length. The length of the C-C single bond between the JH-1 and graphene quantum dot is 1.502 Å. Compared with the length range of C-C single bonds for intra-molecule (1.416-1.542 Å), the bond length at the junction is acceptable, and thus the anchoring of graphene quantum dots can be stable.



3.2. Frontier Molecular Orbitals (FMOs) Analysis The intra-molecular electron transfer can be reflected by the frontier molecular orbitals to some extent. In addition, the energy levels of the frontier molecular orbital scan reflect the stability of the ground state sensitizer and the difficulty of changing into an excited state after being induced by incident light. Table 3 lists the orbital energy levels and energy gaps of the sensitizer before and after the anchoring of the graphene quantum dot. As shown, the HOMO level of JH-1 and JH-1/GR are located at -4.98 and -4.995 eV, respectively, and the HOMO of the sensitizer anchoring graphene quantum dot is slight downshifted about 0.01 eV, indicating that the ground state sensitizer are more stable after anchoring graphene, and this is based on the principle of lowest energy. The simulated LUMOs are -2.86 and -3.00 eV for JH-1 and JH-1/GR, respectively, which indicated that the sensitizer was more easily excited by incident light after anchoring of graphene quantum dot, which was beneficial to control of sensitizer. Therefore, the nonlinear optical switch can be used to control intra-molecular electron transfer. The HOMOs of sensitizers are all lower than the redox potential (-4.8 eV) of electrolyte (I3-/I-), and the LUMOs are all higher than the edge energy of TiO2 semiconductor, therefore, the sensitizers can successfully conduct dye regeneration and interface electron injection. In addition, the decrease of energy gap is conducive to the dye excitation, which is beneficial to absorb radiation of the sensitizer in the long-wavelength region. By comparing the data, it can be found that the energy gap becomes smaller after introduction of graphene quantum dot. Figure 2 shows the electron density distribution of the frontier molecular orbitals after the anchored graphene quantum dot. For JH-1, the electron density on the HOMO is mainly distributed on the TPA and DTT moiety, and the vast number of electron density at LUMO is localized on the CAA and adjacent DTT part. When the graphene quantum dot anchored to the sensitizer, the electron density on the LUMO showed a tendency of electron transfer to the quantum dot, which undoubtedly increased the distance of charge transfer (𝐷𝐶𝑇) and made the charge separation more obvious. Graphene as a material with excellent electron transfer capacity can accelerate electron injection at the interface as long as it is plated on the surface of the semiconductor substrate and anchored by the sensitizer JH-1. 3.3. Ionization Potentials (IP) and Electron Affinities (EA) The ability of the sensitizer to inject electrons into the semiconductor photo-anode can be demonstrated by IP, which can be obtained by subtracting the


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energy of the ground-state neutral sensitizer from that of the cationic sensitizer. The ability of the sensitizer to obtain electrons from the electrolyte can be reflected by EA, which can be obtained by subtracting the energy of the anionic sensitizer from that of the ground-state neutral sensitizer. Both smaller IP and larger EA are conducive to reducing the energy barrier of electron transfer within DSSC. The IP and EA values of the sensitizer and the complex of anchoring quantum dot calculated are listed in Table 4. It can be seen from the calculated results that the ability of losing electrons is unchanged after anchored the graphene quantum dot; but the ability to gain electrons from

the

electrolyte

increases,

which

promotes

the

reduction

rate

of

sensitizer-electrolyte system. 3.4. Reorganization Energy The Reorganization energy can directly reflect the capability of electron transfer. Most electron transfer reactions occur in solution, and the theoretical calculation of reorganization energy of electron transfer in the solvent is still improved due to the complexity of interaction between solute and solvent molecules. According to the Marcus electron transfer theory,45 the charge transfer rate can be expressed in the following formula: κET = Aexp

[ ] ―λ 4κBT

(1)

Where λ represents the reorganization energy, A means electronic coupling, KB stands for the Boltzmann constant and T means the temperature. Reorganization energy consists of intramolecular reorganization energy and solvent reorganization energy,46 and solvent reorganization energy is known as intermolecular recombination energy. Intermolecular recombination energy is affected by the polarization effect of the external environment, so it is not suitable for theoretical simulation.47 However, the intramolecular recombination energies (λe and λh) are relatively small system and can be calculated. Smaller recombination can be more conducive to electronic transfer performance. The λe represents the reorganization energy of the electron, and the λh means the reorganization energy of the hole, which can be formulated as follows:

e   E0  E    E0  E0  h   E0  E    E0  E0 

,

(2)

here, 𝐸0+ (𝐸0― ) means the energy of cation (anion) state under the optimized neutral molecule. 𝐸 + (𝐸 ― ) represents the optimized energy under the cation (anion) state. 𝐸0+ (𝐸0― ) stands for the energy of the neutral formunderthe cation (anion) optimized



state; and E0 is the energy of the optimized neutral structure. The results in Table 4 show that the calculated λe and λh are both in this order: JH-1 < JH-1/GR, which indicates that graphene quantum dots inhibit the electron transport capacity inside the sensitizer, which in turn promotes the interaction between the sensitizer and the quantum dots. 3.5. Optical Properties The performance of the sensitizer can be macroscopically reflected by ultraviolet-visible absorption spectra, and the sensitizer should be able to absorb a large amount of solar photon in the near infrared region. The absorption spectra of the simulated sensitizer and its quantum dots are shown in Figure 3. At the same time, the wavelength of the maximum absorption peak (𝜆𝑎𝑝), the oscillator strength (f), vertical excitation energy (EG-E) and orbital contribution are summarized in Table 5. After the doping of graphene, the strongest excited state of the complex is changed from S1 of the isolated molecule to S2, and the red shift absorption of 𝜆𝑎𝑝 from 450.74 nm to 458.45 nm. In addition, the absorption strength at the 𝜆𝑎𝑝of the sensitizer is increased from 1.988 to 2.563 after doping graphene quantum dots, and the vertical excitation energy is also dropped from 2.75 eV to 2.70 eV. When the absorption spectrum of the visible light region is red-shifted, it is more conducive to improve the light harvesting efficiency (LHE) of the dye, meaning that the more excellent short-circuit current will be generated. At the same time, when the intensity of absorption spectrum is relatively large, it is beneficial to promote the light harvesting efficiency to reach 100% in any visible range. Therefore, the anchoring graphene system theoretically boosts short-circuit current in solar cells. In addition, from the perspective of photo-excited single molecule system, the anchoring graphene has reduced the vertical excitation energy, which makes the energy of exciting dyes lower, indicating that the doping of quantum dots is conducive to the optical transitions. 3.6. Electric Field Controlled NLO Switch The reported material of non-linear optics (NLO) switch contains metal-organic compounds and electride molecules.48-50 However, the application of this property to sensitized material molecules has not been reported. Through preliminary attempts, the non-optical switch effect of the isolated sensitizer in external electric fields is not reflected. But after doped with graphene quantum dot, the idea was confirmed by the interference of a series of the specific external electric fields. In order to verify whether there is NLO switch effect, a stimulation of the external electric field on the sensitizer molecule is required, and the electron density of the sensitizer will change


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significantly, which will result in a very high NLO contrast. Figure 4 shows the molecular orbital (HOMO) evolution of the sensitizer and graphene quantum dot doped complexes under different electric field intensities. The direction of the external electric field is from the molecular donor to the molecular acceptor (TPA→CAA). It can be seen from the evolution of molecular orbital of an isolated molecule that the electron density presents uniform distribution with the increase of the external electric field intensity. When doped with quantum dots, electron density distributions show different characteristics. At an electric field intensity of 20 × 10-4 au, electron density was still distributed in the donor part of the molecule; however, upon electric field intensity F= 25 × 10-4 au, electron density showed polarization, and the graphene quantum dots anchored by CAA will interact with the sensitizer, which was conducive to increase the charge transfer distance (DCT) of the sensitizer. Since the graphene oxide in real conditions contains a large amount of hydroxyl, the graphene quantum dots can be well anchored to the surface of the semiconductor substrate,51 and further accelerating the injection of electrons into the photo-anode. Therefore, electrons transfer can be controlled by NLO switch after sensitizer was doped by graphene quantum dots. 3.7. Electric Field Effects on Optical Property The external electric field will not only affect the electron transfer of the sensitizer molecule, but also affect the optical performance of the sensitizer. The optical properties of dye and its graphene quantum dot complex in the electric field are summarized in Table S1 and Figure 5. The 𝜆𝑎𝑝 of the sensitizer molecule shows a regular red-shifted absorption in the visible region with the increase of the electric field intensity. Therefore, the relationship between 𝜆𝑎𝑝 and the electric field intensity is deeply discussed through the linear fitting, and the results are shown in Figure 6. The coefficient of determination (R2) between 𝜆𝑎𝑝 and the intensity of the external electric field of the two types of photosensitive layers is all greater than 0.9, which indicates that the variation degree of the 𝜆𝑎𝑝, a dependent variable, will be reduced by 90% when the intensity of the electric field is adjusted. Therefore, the results of these two linear fittings are convincing. It can be known from the photon flux curve in the visible region that the intensity of photon flux near 700nm is the strongest,52 and thus the electric field can be regulated to make 𝜆𝑎𝑝 at 700nm. According to the linear fitting results of the isolated sensitizer (y=3.41x+441), the intensity of the external electric field can be controlled around 76 × 10-4 au, and for the fitting curve of the doped quantum dots (y=3.15x+452), the intensity of the external electric field should



be controlled around 79 × 10-4 au. In addition, it was found from the data that the anchoring graphene into dye can increase the determination coefficient, which makes it easier for the applied external electric field to control the bathochromic-shift of the absorption spectrum. 4. Conclusion Summarizing the above analysis, the optimization structures, FMOs, ionization potentials, electron affinities, recombination energies, optical properties, NLO switch and the influence of electric field on optical properties of sensitizer molecule and its complexes doped with graphene quantum dots were systematically and theoretically investigated. The results showed that the HOMO-LUMO gap was significantly reduced after the doping of graphene quantum dots in the photosensitive layer, and it was easier for the photosensitive layer to capture electrons from the electrolyte, which accelerated the redox cycle of the whole system. After the doping of graphene quantum dots, the absorption spectrum of the sensitizer showed a red-shift, which indicates that the doping of graphene quantum dots is conducive to the short-circuit current of DSSC. Through the control analysis of the applied external electric field, it can be found that the electron transfer of the photosensitive layer can be controlled by the electric field after the doping of quantum dots, which makes the external electric field become the NLO switch of the photosensitive layer. When the electric field intensity is in a sensitive range of 20-25 × 10-4 au, the NLO switch is activated, and the electron transfer in the photosensitive layer molecule is controlled by the applied external electric field intensity, which is not available in isolated sensitizers. In addition, the analysis of the optical properties of the sensitizer by the external electric field shows that the absorption spectrum can be regularly red-shifted by adjusting the applied electric field; so the photosensitive layer can be used to capture the solar photon flux to the maximum extent by applying the external electric field. In summary, current work provides theoretical insight into the effects of anchoring graphene quantum dots on DSSC properties, suggesting that doping graphene quantum dots in the photosensitive layer is an alternative approach. Associated Content Supporting Information Calculated Optical Property of JH-1 and JH-1/GR in External Electric Field (×10-4 au), in Which H and L Represent HOMO and LUMO, Respectively. (Table S1) Acknowledgment


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This work was supported by China Postdoctoral Science Foundation (2016M590270),

Heilongjiang

Postdoctoral

Science

Foundation

Grant

(LBH-Z15002), Chengdong Scholar Training Program, National Natural Science Foundation of China (Grant No. 11404055) and the Heilongjiang Province Science Foundation for Youths (QC2013C006) and the Fundamental Research Funds for the Central Universities (2572018BC24). Conflicts of Interest: The authors declare no conflict of interest. References (1) O'Regan, B.; Gratzel, M. A low-Cost, High-Efficiency Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films. Nature 1991, 353, 737-740. (2) Ren, Y.; Sun, D.; Cao, Y.; Tsao, H. N.; Yuan, Y.; Zakeeruddin, S. M.; Wang, P.; Gratzel, M. A Stable Blue Photosensitizer for Color Palette of Dye-Sensitized Solar Cells Reaching 12.6% Efficiency. J. Am. Chem. Soc. 2018, 140, 2405-2408. (3) Jradi, F. M.; Kang, X. W.; O'Neil, D.; Pajares, G.; Getmanenko, Y. A.; Szymanski, P.; Parker, T. C.; El-Sayed, M. A.; Marder, S. R. Near-Infrared Asymmetrical Squaraine Sensitizers for Highly Efficient Dye Sensitized Solar Cells: The Effect of pi-Bridges and Anchoring Groups on Solar Cell Performance. Chem. Mat. 2015, 27, 2480-2487. (4) Freitag, M.; Teuscher, J.; Saygili, Y.; Zhang, X.; Giordano, F.; Liska, P.; Hua, J.; Zakeeruddin, S. M.; Moser, J.-E.; Grätzel, M.; Hagfeldt, A. Dye-Sensitized Solar Cells for Efficient Power Generation under Ambient Lighting. Nat. Photonics 2017, 11, 372-378. (5) Tingare, Y. S.; Vinh, N. S.; Chou, H. H.; Liu, Y. C.; Long, Y. S.; Wu, T. C.; Wei, T. C.; Yeh, C. Y. New Acetylene-Bridged 9,10-Conjugated Anthracene Sensitizers: Application in Outdoor and Indoor Dye-Sensitized Solar Cells. Adv. Energy Mater. 2017, 7, No. 1700032. (6) Yao, Z. Y.; Zhang, M.; Wu, H.; Yang, L.; Li, R. Z.; Wang, P. Donor/Acceptor Indenoperylene Dye for Highly Efficient Organic Dye-Sensitized Solar Cells. J. Am. Chem. Soc. 2015, 137, 3799-3802. (7) Wang, X.; Li, Y.; Song, P.; Ma, F.; Mi, L.; Yang, Y. Molecular Engineering Mechanism of Organic Photoactive Layer by Alkyl Chains, 4-Butoxyphenyl and Cyanogroup. Spectrochim. Acta, Part A 2019, 218, 142-154. (8) Jin, X. Y.; Sun, L. B.; Li, D. Y.; Wang, C. L.; Bai, F. Q. Efficiency Difference Between Furan- and Thiophene-Based D--A Dyes in DSSCs Explained by Theoretical



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benzothiophene

pi-Spacer-Based

D-pi-A

Organic

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for

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Table 1. Experimental and Calculated Maximum Absorption Peaks (nm) of JH-1 in Ethanol by the TD-DFT with Different Functionals at 6-31G(d) Basis Set.

JH-1 a

M062X Cam-B3LYP PBEPBE

ωB97X

MPW1PW91

Exp. a

491.68

450.74

605.14

450

489.50

1021.68

Maximum absorption peak in experiment.


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Table 2. Selected Dihedral Angles (Units in °) of the Sensitizer and Its Graphene Complexes. Dye

θ1

θ2

θ3

θ4

JH-1

39.57

10.83

1.37

1.31

JH-1/GR

41.22

12.36

2.07

1.25



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Table 3. Energy Levels and Energy Gaps (∆𝐇 ― 𝐋) of JH-1 and JH-1/GR in Solvent (eV). JH-1 JH-1/GR

HOMO -4.98 -4.99

LUMO -2.86 -3.00


∆H ― L 2.12 1.99

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Table 4. Ionization Potentials (IP), Electron Affinities (EA) and Reorganization Energy of JH-1 and JH-1/GR (eV). JH-1 JH-1/GR

IP 4.78 4.78

EA 3.10 3.15


𝜆𝑒 0.25 0.26

𝜆ℎ 0.23 0.24


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Table 5. The Calculated Transition Properties of JH-1 and JH-1/GR in Ethanol via TD-DFT//ωB97X/6-31G(d). Dyes JH-1

JH-1/GR

State S1 S2 S3 S1 S2 S3

EG-E (eV) 2.75 3.65 4.29 2.67 2.70 2.90

𝜆𝑎𝑝(nm) 450.74 339.80 288.77 463.98 458.45 427.93

Contribution MO (40.1%)H→L (43.9%)H→L+1 (29.6%)H→L+2 (39.8%)H→L+1 (37.0%)H-3→L (38.2%)H-3→L


Strength f 1.988 0.356 0.547 0.002 2.563 0.015

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Figure Captions: Figure 1. Chemical structure of JH-1. Figure 2. Selected frontier molecular orbitals of JH-1 and JH-1/GR in ethanol. Figure 3. Simulated UV-Vis spectra of JH-1 and JH-1/GR in ethanol. Figure 4. Excess electron orbital (HOMO) evolve with increasing electric field strength. Figure 5. Simulated UV-Vis spectra of JH-1 and JH-1/GR in under different electric field intensities (×10-4 au),a) JH-1, b)JH-1/GR. Figure 6. Linear fitting analyses of the Absorption peak (λabs) evolve with increasing electric field strength, a) JH-1 and b) JH-1/GR.



Figure 1. Chemical structure of JH-1.

S22


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JH-1

JH-1/GR

HOMO

HOMO-3

LUMO

HOMO

LUMO+2

LUMO

Figure 2. Selected frontier molecular orbitals of JH-1 and JH-1/GR in ethanol.

S23



Figure 3. Simulated UV-Vis spectra of JH-1 and JH-1/GR in ethanol.

S24


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Field(10-4au)

JH-1

JH-1/GR

0

5

10

15

20

25

Figure 4. Excess electron orbital (HOMO) evolve with increasing electric field strength.

S25



Figure 5. Simulated UV-Vis spectra of JH-1 and JH-1/GR in under different electric field intensities (×10-4 au),a) JH-1, b)JH-1/GR.

S26


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Figure 6. Linear fitting analyses of the absorption peak (𝜆𝑎𝑝) evolve with increasing electric field strength, a) JH-1 and b) JH-1/GR.

S27



TOC Graphic

S28


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Second-Order Nonlinear Optical Switch Manipulation of

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