Spectroscopic Characterization of Fluorinated Benzylphosphonic Acid

Dec 12, 2016 - Spectroscopic Characterization of Fluorinated Benzylphosphonic Acid Monolayers on AlOx/Al Surfaces. William E. Ford†, Ffion Abraham§...
0 downloads 0 Views 4MB Size
Article pubs.acs.org/JPCC

Spectroscopic Characterization of Fluorinated Benzylphosphonic Acid Monolayers on AlOx/Al Surfaces William E. Ford,*,† Ffion Abraham,§ Frank Scholz,† Gabriele Nelles,† Graham Sandford,§ and Florian von Wrochem*,† †

Sony Europe Limited, Materials Science Laboratory, Hedelfinger Strasse 61, Stuttgart 70327, Germany Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom

§

S Supporting Information *

ABSTRACT: We recently reported on how the surface energy and work function of AlOx/Al substrates can be tuned by selfassembled monolayers of fluorinated and nonfluorinated benzylphosphonic acid derivatives in view of organic electronic applications. In this contribution, we present a thorough investigation of these monolayers by photoemission (XPS) and infrared (PM-IRRAS) spectroscopies, to provide a quantitative understanding of their structural properties (packing density and orientation) and chemical composition. A detailed analysis of XPS chemical shifts makes an assignment of the carbon species present in the SAMs feasible, from the low-binding-energy aromatic carbon (∼284.5 eV) to the highly electronegative fluorine-substituted carbon (∼287.5 eV), whereby an upper limit for the fraction of nonspecific hydrocarbons (1050 cm−1 due to the PMIRRAS background absorption band associated with vibrations of Al−O in the AlOx layer at 955 cm−1, where P−O−H and P− O−Al also occur.71,100 The symmetric and asymmetric stretching bands of the PO32− group are found in the 1200− 1000 cm−1 range, but these tend to be quite broad.100 Therefore, the νPO band is left as the primary vibration within the PO3 moiety to provide information about bonding within the series of SAMs investigated herein. The PO stretching vibration of PA derivatives is found in the 1300−1200 cm−1 range. This band appears in the powder (KBr) spectra of 9, 10, 2, and 11 at 1263, 1253, 1285, and 1267 cm−1, respectively (Table 1). The only SAM spectrum in which the νPO band clearly appears is that of SAM 6 (at 1276 cm−1, Figure S2). This information alone does not distinguish

between the possible binding modes, but it is useful when considered together with the scissoring vibration of the CH2 group. The band for the scissoring vibration, which is found in the powder spectra of all 11 PAs at 1407 ± 7 cm−1 (Figure S3), is absent in all 11 SAM spectra (Figure S2). Ideally, the TDM for this vibration should be parallel to both the methylene H− C−H plane and the P−C−C plane, but there are deviations due to vibronic couplings with adjacent groups. Nearly ideal is the mode at 1401 cm−1 of 9 (Figure S4), where there is only a minor deviation because of contributions from the ring. A larger deviation is seen in the modes at 1413 and 1417 cm−1 for 11 (Figure S7), where the TDM is nearly perpendicular to the plane of the P−C−C group due to strong coupling of the CH2 scissor with the ν15 ring mode. In the tridentate binding mode, the P−C bond is expected to be normal to the AlOx/Al surface, so that the TDM of the scissor vibration is ∼35° from the surface normal, whereas in the bidentate mode the TDM is ∼90° from the surface normal (i.e., parallel to the surface).32 Our IR data thus support the bidentate over the tridentate mode. This conclusion applies to the monodentate configuration as well, where the P−C bond is also expected to be normal to the surface (Figure 9), but the single P−O−Al bond connection makes orientation of the P−C bond subject to alteration by intermolecular interactions, such as hydrogen bonding of the free P−OH or PO groups.85,95,99 Preferential binding through bidentate mode as suggested above is consistent with the absence of the νPO band in the SAMs (except for SAM 6), because the TDMs of the PO and CH2 vibrations have similar directions (Figures S4−S7). However, we note that the protonation of the bonded PO3 group (Figure 9c) or hydrogen bonding of PO with a neighboring Al−OH (Figure 9d) or P−OH (Figure 9e) group might also result in attenuation of the νPO band.85,95,99



CONCLUSIONS We have presented a detailed XPS and PM-IRRAS survey of monolayers of 10 benzylphosphonic acid derivatives on AlOx/ Al. These PAs differ in the number of phenyl rings (1 or 2), the fluorine substitution pattern (2, 4, or 5), and/or in terminal methoxy ring substitution. Dodecylphosphonic acid was included in this study as a reference. From XPS, we conclude that well-defined SAMs were formed with the expected chemical composition. A careful analysis of C 1s chemical shifts enabled us to draw conclusions on the molecular structure within the SAMs as well as on the upper limits to the amount of nonspecific contaminants. IR characterization of all PAs was carried out, both as monolayers and in the bulk, where DFT calculations of four representative PAs made it possible to identify several IR bands that are characteristic for benzylphosphonic acids. In particular, a distinct three-band pattern due to the benzyl CH2 group has been identified involving a Fermi resonance interaction between the symmetric J

DOI: 10.1021/acs.jpcc.6b11089 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C stretching vibration and the first overtone of the CH2 scissoring vibration. We are aware of only one previous example in which the IR signature of the benzyl CH2 group has been unambiguously identified in a SAM.92 Furthermore, absence of the CH2 scissoring and PO stretching bands in the PMIRRAS spectra indicate that the PO3 moiety chemisorbs to the AlOx/Al substrate via a bidentate rather than tridentate or monodentate mode.



Organic Electronic Devices Using Self-Assembled Monolayers. Appl. Phys. Lett. 1997, 71, 3528−3530. (10) de Boer, B.; Hadipour, A.; Mandoc, M. M.; van Woudenbergh, T.; Blom, P. W. M. Tuning of Metal Work Functions with SelfAssembled Monolayers. Adv. Mater. 2005, 17, 621−625. (11) Ford, W. E.; Gao, D.; Knorr, N.; Wirtz, R.; Scholz, F.; Karipidou, Z.; Ogasawara, K; Rosselli, S.; Rodin, V.; Nelles, G.; von Wrochem, F. Organic Dipole Layers for Ultralow Work Function Electrodes. ACS Nano 2014, 8, 9173−9180. (12) Campbell, I. H.; Rubin, S.; Zawodzinski, T. A.; Kress, J. D.; Martin, R. L.; Smith, D. L.; Barashkov, N. N.; Ferraris, J. P. Controlling Schottky Energy Barriers in Organic Electronic Devices Using SelfAssembled Monolayers. Phys. Rev. B: Condens. Matter Mater. Phys. 1996, 54, R14321−R14324. (13) Ulman, A. Formation and Structure of Self-Assembled Monolayers. Chem. Rev. 1996, 96, 1533−1554. (14) Lee, J.; Jung, B. J.; Lee, J. I.; Chu, H. Y.; Do, L. M.; Shim, H. K. Modification of an ITO Anode with a Hole-Transporting SAM for Improved OLED Device Characteristics. J. Mater. Chem. 2002, 12, 3494−3498. (15) Turak, A. Interfacial Degradation in Organic Optoelectronics. RSC Adv. 2013, 3, 6188−6225. (16) Hotchkiss, P. J.; Li, H.; Paramonov, P. B.; Paniagua, S. A.; Jones, S. C.; Armstrong, N. R.; Bredas, J. L.; Marder, S. R. Modification of the Surface Properties of Indium Tin Oxide with Benzylphosphonic Acids: A Joint Experimental and Theoretical Study. Adv. Mater. 2009, 21, 4496−4501. (17) Knesting, K. M.; Hotchkiss, P. J.; MacLeod, B. A.; Marder, S. R.; Ginger, D. S. Spatially Modulating Interfacial Properties of Transparent Conductive Oxides: Patterning Work Function with Phosphonic Acid Self-Assembled Monolayers. Adv. Mater. 2012, 24, 642−646. (18) Wood, C.; Li, H.; Winget, P.; Brédas, J. L. Binding Modes of Fluorinated Benzylphosphonic Acids on the Polar ZnO Surface and Impact on Work Function. J. Phys. Chem. C 2012, 116, 19125−19133. (19) MacLeod, B. A.; Horwitz, N. E.; Ratcliff, E. L.; Jenkins, J. L.; Armstrong, N. R.; Giordano, A. J.; Hotchkiss, P. J.; Marder, S. R.; Campbell, C. T.; Ginger, D. S. Built-In Potential in Conjugated Polymer Diodes with Changing Anode Work Function: Interfacial States and Deviation from the Schottky−Mott Limit. J. Phys. Chem. Lett. 2012, 3, 1202−1207. (20) Ndione, P. F.; Garcia, A.; Widjonarko, N. E.; Sigdel, A. K.; Steirer, K. X.; Olson, D. C.; Parilla, P. A.; Ginley, D. S.; Armstong, N. R.; Richards, R. E.; et al. Highly-Tunable Nickel Cobalt Oxide as a Low-Temperature P-Type Contact in Organic Photovoltaic Devices. Adv. Energy Mater. 2013, 3, 524−531. (21) Bulusu, A.; Paniagua, S. A.; MacLeod, B. A.; Sigdel, A. K.; Berry, J. J.; Olson, D. C.; Marder, S. R.; Graham, S. Efficient Modification of Metal Oxide Surfaces with Phosphonic Acids by Spray Coating. Langmuir 2013, 29, 3935−3942. (22) Knesting, K. M.; Ju, H.; Schlenker, C. W.; Giordano, A. J.; Garcia, A.; Smith, O. N. L.; Olson, D. C.; Marder, S. R.; Ginger, D. S. ITO Interface Modifiers Can Improve VOC in Polymer Solar Cells and Suppress Surface Recombination. J. Phys. Chem. Lett. 2013, 4, 4038−4044. (23) Li, H.; Ratcliff, E. L.; Sigdel, A. K.; Giordano, A. J.; Marder, S. R.; Berry, J. J.; Brédas, J. L. Modification of the Gallium-Doped Zinc Oxide Surface with Self-Assembled Monolayers of Phosphonic Acids: A Joint Theoretical and Experimental Study. Adv. Funct. Mater. 2014, 24, 3593−3603. (24) Lange, I.; Reiter, S.; Pätzel, M.; Zykov, A.; Nefedov, A.; Hildebrandt, J.; Hecht, S.; Kowarik, S.; Wöll, C.; Heimel, G.; et al. Tuning the Work Function of Polar Zinc Oxide Surfaces using Modified Phosphonic Acid Self-Assembled Monolayers. Adv. Funct. Mater. 2014, 24, 7014−7024. (25) Shao, G.; Glaz, M. S.; Ma, F.; Ju, H.; Ginger, D. S. IntensityModulated Scanning Kelvin Probe Microscopy for Probing Recombination in Organic Photovoltaics. ACS Nano 2014, 8, 10799−10807.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpcc.6b11089. Additional XPS and IR data, as well as transition dipole moments and vibrational modes from DFT simulations (PDF)



AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Graham Sandford: 0000-0002-3266-2039 Florian von Wrochem: 0000-0003-2298-9270 Notes

The authors declare no competing financial interest.



ACKNOWLEDGMENTS We thank Josef Michl and Michael Zharnikov for helpful discussions and Felix Hanke from Biovia for his support in the graphical representation of transition dipole moments from DFT calculations.



REFERENCES

(1) Mathijssen, S. G. J.; van Hal, P. A.; van den Biggelaar, T. J. M.; Smits, E. C. P.; de Boer, B.; Kemerink, M.; Janssen, R. A. J.; de Leeuw, D. M. Manipulating the Local Light Emission in Organic LightEmitting Diodes by using Patterned Self-Assembled Monolayers. Adv. Mater. 2008, 20, 2703−2706. (2) Sirringhaus, H. Device Physics of Solution-Processed Organic Field-Effect Transistors. Adv. Mater. 2005, 17, 2411−2425. (3) Klauk, H.; Zschieschang, U.; Pflaum, J.; Halik, M. Ultralow-Power Organic Complementary Circuits. Nature 2007, 445, 745−748. (4) Halik, M.; Klauk, H.; Zschieschang, U.; Schmid, G.; Dehm, C.; Schutz, M.; Maisch, S.; Effenberger, F.; Brunnbauer, M.; Stellacci, F. Low-voltage Organic Transistors with an Amorphous Molecular Gate Dielectric. Nature 2004, 431, 963−966. (5) Gillaizeau-Gauthier, I.; Odobel, F.; Alebbi, M.; Argazzi, R.; Costa, E.; Bignozzi, C. A.; Qu, P.; Meyer, G. J. Phosphonate-Based Bipyridine Dyes for Stable Photovoltaic Devices. Inorg. Chem. 2001, 40, 6073− 6079. (6) Zschieschang, U.; Yamamoto, T.; Takimiya, K.; Kuwabara, H.; Ikeda, M.; Sekitani, T.; Someya, T.; Klauk, H. Organic Electronics on Banknotes. Adv. Mater. 2011, 23, 654−658. (7) Abraham, F.; Ford, W. E.; Scholz, F.; Nelles, G.; Sandford, G.; von Wrochem, F. Surface Energy and Work Function Control of AlOx/Al Surfaces by Fluorinated Benzylphosphonic Acids. ACS Appl. Mater. Interfaces 2016, 8, 11857−11867. (8) Heimel, G.; Romaner, L.; Zojer, E.; Brédas, J.-L. The Interface Energetics of Self-Assembled Monolayers on Metals. Acc. Chem. Res. 2008, 41, 721−729. (9) Campbell, I. H.; Kress, J. D.; Martin, R. L.; Smith, D. L.; Barashkov, N. N.; Ferraris, J. P. Controlling Charge Injection in K

DOI: 10.1021/acs.jpcc.6b11089 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C (26) Sang, L.; Mudalige, A.; Sigdel, A. K.; Giordano, A. J.; Marder, S. R.; Berry, J. J.; Pemberton, J. E. PM-IRRAS Determination of Molecular Orientation of Phosphonic Acid Self-Assembled Monolayers on Indium Zinc Oxide. Langmuir 2015, 31, 5603−5613. (27) Paniagua, S. A.; Hotchkiss, P. J.; Jones, S. C.; Marder, S. R.; Mudalige, A.; Marrikar, F. S.; Pemberton, J. E.; Armstrong, N. R. Phosphonic Acid Modification of Indium − Tin Oxide Electrodes: Combined XPS/UPS/Contact Angle Studies. J. Phys. Chem. C 2008, 112, 7809−7817. (28) Lange, I.; Reiter, S.; Kniepert, J.; Piersimoni, F.; Pätzel, M.; Hildebrandt, J.; Brenner, T.; Hecht, S.; Neher, D. Zinc Oxide Modified with Benzylphosphonic Acids as Transparent Electrodes in Regular and Inverted Organic Solar Cell Structures. Appl. Phys. Lett. 2015, 106, 113302. (29) Hanson, E. L.; Schwartz, J.; Nickel, B.; Koch, N.; Danisman, M. F. Bonding Self-Assembled, Compact Organophosphonate Monolayers to the Native Oxide Surface of Silicon. J. Am. Chem. Soc. 2003, 125, 16074−16080. (30) Goetting, L. B.; Deng, T.; Whitesides, G. M. Microcontact Printing of Alkanephosphonic Acids on Aluminum: Pattern Transfer by Wet Chemical Etching. Langmuir 1999, 15, 1182−1191. (31) Levine, I.; Weber, S. M.; Feldman, Y.; Bendikov, T.; Cohen, H.; Cahen, D.; Vilan, A. Molecular Length, Monolayer Density, and Charge Transport: Lessons from Al-AlOx/Alkyl−Phosphonate/Hg Junctions. Langmuir 2012, 28, 404−415. (32) Pellerite, M. J.; Dunbar, T. D.; Boardman, L. D.; Wood, E. J. Effects of Fluorination on Self-Assembled Monolayer Formation from Alkanephosphonic Acids on Aluminum: Kinetics and Structure. J. Phys. Chem. B 2003, 107, 11726−11736. (33) Foster, T. T.; Alexander, M. R.; Leggett, G. J.; McAlpine, E. Friction Force Microscopy of Alkylphosphonic Acid and Carboxylic Acids Adsorbed on the Native Oxide of Aluminum. Langmuir 2006, 22, 9254−9259. (34) Hoque, E.; DeRose, J. A.; Kulik, G.; Hoffmann, P.; Mathieu, H. J.; Bhushan, B. Alkylphosphonate Modified Aluminum Oxide Surfaces. J. Phys. Chem. B 2006, 110, 10855−10861. (35) Thissen, P.; Valtiner, M.; Grundmeier, G. Stability of Phosphonic Acid Self-Assembled Monolayers on Amorphous and Single-Crystalline Aluminum Oxide Surfaces in Aqueous Solution. Langmuir 2010, 26, 156−164. (36) Liakos, I. L.; Newman, R. C.; McAlpine, E.; Alexander, M. R. Comparative Study of Self-Assembly of a Range of Monofunctional Aliphatic Molecules on Magnetron-Sputtered Aluminium. Surf. Interface Anal. 2004, 36, 347−354. (37) Schreiber, F. Structure and Growth of Self-Assembling Monolayers. Prog. Surf. Sci. 2000, 65, 151−256. (38) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865−3868. (39) Stammer, X.; Tonigold, K.; Bashir, A.; Kafer, D.; Shekhah, O.; Hulsbusch, C.; Kind, M.; Grob, A.; Wöll, C. A Highly Ordered, Aromatic Bidentate Self-Assembled Monolayer on Au(111): a Combined Experimental and Theoretical Study. Phys. Chem. Chem. Phys. 2010, 12, 6445−6454. (40) Lindberg, B. J.; Hamrin, K.; Johansson, G.; Gelius, U.; Fahlman, A.; Nordling, C.; Siegbahn, K. Molecular Spectroscopy by Means of ESCA. Phys. Scr. 1970, 1, 286−298. (41) Love, J. C.; Estroff, L. A.; Kriebel, J. K.; Nuzzo, R. G.; Whitesides, G. M. Self-Assembled Monolayers of Thiolates on Metals as a Form of Nanotechnology. Chem. Rev. 2005, 105, 1103−1169. (42) Bain, C. B.; Troughton, E. B.; Tao, Y.-T.; Evall, J.; Whitesides, G. M.; Nuzzo, R. G. Formation of Monolayer Films by the Spontaneous Assembly of Organic Thiols from Solution onto Gold. J. Am. Chem. Soc. 1989, 111, 321−335. (43) Chesneau, F.; Schupbach, B.; Szelagowska-Kunstman, K.; Ballav, N.; Cyganik, P.; Terfort, A.; Zharnikov, M. Self-Assembled Monolayers of Perfluoroterphenyl-Substituted Alkanethiols: Specific Characteristics and Odd-Even Effects. Phys. Chem. Chem. Phys. 2010, 12, 12123−12137.

(44) Duwez, A.-S. Exploiting Electron Spectroscopies to Probe the Structure and Organization of Self-Assembled Monolayers: a Review. J. Electron Spectrosc. Relat. Phenom. 2004, 134, 97−138. (45) Strohmeier, B. R. An ESCA Method for Determining the Oxide Thickness on Aluminum Alloys. Surf. Interface Anal. 1990, 15, 51−56. (46) Sambe, H.; Ramaker, D. E. X-ray Photoelectron Spectroscopy Study on the Electrical Double Layer at an Al203-Al Interface. J. Vac. Sci. Technol., A 1992, 10, 2991−2995. (47) Baer, D. R.; Engelhard, M. H.; Gaspar, D. J.; Lea, A. S.; Windisch, J. Use and Limitations of Electron Flood Gun Control of Surface Potential During XPS: Two non-Homogeneous Sample Types. Surf. Interface Anal. 2002, 33, 781−790. (48) NIST X-ray Photoelectron Spectroscopy Database 20, Version 4.1, 2012. Available at the following: https://srdata.nist.gov/xps/. (49) Golden, W. G.; Snyder, C. D.; Smith, B. Infrared ReflectionAbsorption Spectra of Ordered and Disordered Arachidate Monolayers on Aluminum. J. Phys. Chem. 1982, 86, 4675−4678. (50) Tao, Y. T.; Hietpas, G. D.; Allara, D. L. HCl Vapor-Induced Structural Rearrangements of n-Alkanoate Self-Assembled Monolayers on Ambient Silver, Copper, and Aluminum Surfaces. J. Am. Chem. Soc. 1996, 118, 6724−6735. (51) Pertays, K. M.; Thompson, G. E.; Alexander, M. R. SelfAssembly of Stearic Acid on Aluminium: the Importance of Oxide Surface Chemistry. Surf. Interface Anal. 2004, 36, 1361−1366. (52) Giza, M.; Thissen, P.; Grundmeier, G. Adsorption Kinetics of Organophosphonic Acids on Plasma-Modified Oxide-Covered Aluminum Surfaces. Langmuir 2008, 24, 8688−8694. (53) Greenler, R. G. Infrared Study of Adsorbed Molecules on Metal Surfaces by Reflection Techniques. J. Chem. Phys. 1966, 44, 310−315. (54) Debe, M. K. Extracting Physical Structure Information from Thin Organic Films with Reflection Absorption Infrared Spectroscopy. J. Appl. Phys. 1984, 55 (9), 3354−3366. (55) Chidsey, C. E. D.; Loiacono, D. N. Chemical Functionality in Self-assembled Monolayers: Structural and Electrochemical Properties. Langmuir 1990, 6, 682−691. (56) Parikh, A. N.; Allara, D. L. Quantitative Determination of Molecular Structure in Multilayered Thin Films of Biaxial and Lower Symmetry from Photon Spectroscopies. I. Reflection Infrared Vibrational Spectroscopy. J. Chem. Phys. 1992, 96, 927−945. (57) Barner, B. J.; Green, M. J.; Saez, E. I.; Corn, R. M. Polarization Modulation Fourier Transform Infrared Reflectance Measurements of Thin Films and Monolayers at Metal Surfaces Utilizing Real-Time Sampling Electronics. Anal. Chem. 1991, 63, 55−60. (58) Han, S. W.; Kim, C. H.; Hong, S. H.; Chung, Y. K.; Kim, K. Azobenzene-Incorporated Alkanethiol Monolayer Film on Au(111): Reflection−Absorption Infrared Spectroscopy and Atomic Force Microscopy Study. Langmuir 1999, 15, 1579−1583. (59) Rong, H. T.; Frey, S.; Yang, Y. J.; Zharnikov, M.; Buck, M.; Wühn, M.; Wöll, C.; Helmchen, G. On the Importance of the Headgroup Substrate Bond in Thiol Monolayers: A Study of BiphenylBased Thiols on Gold and Silver. Langmuir 2001, 17, 1582−1593. (60) Duan, L.; Garrett, S. J. An Investigation of Rigid pMethylterphenyl Thiol Self-Assembled Monolayers on Au(111) Using Reflection−Absorption Infrared Spectroscopy and Scanning Tunneling Microscopy. J. Phys. Chem. B 2001, 105, 9812−9816. (61) Malicki, M.; Guan, Z.; Ha, S. D.; Heimel, G.; Barlow, S.; Rumi, M.; Kahn, A.; Marder, S. R. Preparation and Characterization of 4− Donor Substituted Stilbene-4-thiolate Monolayers and Their Influence on the Work Function of Gold. Langmuir 2009, 25, 7967−7975. (62) Dauselt, J.; Zhao, J.; Kind, M.; Binder, R.; Bashir, A.; Terfort, A.; Zharnikov, M. Compensation of the Odd−Even Effects in Araliphatic Self-Assembled Monolayers by Nonsymmetric Attachment of the Aromatic Part. J. Phys. Chem. C 2011, 115, 2841−2854. (63) Azzam, W.; Bashir, A.; Ulrich Biedermann, P.; Rohwerder, M. Formation of Highly Ordered and Orientated Gold Islands: Effect of Immersion Time on the Molecular Adlayer Structure of Pentafluorobenzenethiols (PFBT) SAMs on Au(111). Langmuir 2012, 28, 10192−10208. L

DOI: 10.1021/acs.jpcc.6b11089 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C (64) Vahlberg, C.; Linares, M.; Norman, P.; Uvdal, K. Phenylboronic Ester- and Phenylboronic Acid-Terminated Alkanethiols on Gold Surfaces. J. Phys. Chem. C 2012, 116, 796−806. (65) Gliboff, M.; Sang, L.; Knesting, K. M.; Schalnat, M. C.; Mudalige, A.; Ratcliff, E. L.; Li, H.; Sigdel, A. K.; Giordano, A. J.; Berry, J. J.; et al. Orientation of Phenylphosphonic Acid Self-Assembled Monolayers on a Transparent Conductive Oxide: A Combined NEXAFS, PM-IRRAS, and DFT Study. Langmuir 2013, 29, 2166− 2174. (66) Abu-Husein, T.; Schuster, S.; Egger, D. A.; Kind, M.; Santowski, T.; Wiesner, A.; Chiechi, R.; Zojer, E.; Terfort, A.; Zharnikov, M. The Effects of Embedded Dipoles in Aromatic Self-Assembled Monolayers. Adv. Funct. Mater. 2015, 25, 3943−3957. (67) Zhang, Z.; Wächter, T.; Kind, M.; Schuster, S.; Bats, J. W.; Nefedov, A.; Zharnikov, M.; Terfort, A. Self-Assembled Monolayers of Perfluoroanthracenylaminoalkane Thiolates on Gold as Potential Electron Injection Layers. ACS Appl. Mater. Interfaces 2016, 8, 7308−7319. (68) Frey, B. L.; Hanken, D. G.; Corn, R. M. Vibrational Spectroscopic Studies of the Attachment Chemistry for Zirconium Phosphonate Multilayers at Gold and Germanium Surfaces. Langmuir 1993, 9, 1815−1820. (69) Schulmeyer, T.; Paniagua, S. A.; Veneman, P. A.; Jones, S. C.; Hotchkiss, P. J.; Mudalige, A.; Pemberton, J. E.; Marder, S. R.; Armstrong, N. R. Modification of BaTiO3 Thin Films: Adjustment of the Effective Surface Work Function. J. Mater. Chem. 2007, 17, 4563− 4570. (70) Pawsey, S.; McCormick, M.; De Paul, S.; Graf, R.; Lee, Y. S.; Reven, L.; Spiess, H. W. 1H Fast MAS NMR Studies of HydrogenBonding Interactions in Self-Assembled Monolayers. J. Am. Chem. Soc. 2003, 125, 4174−4184. (71) Szillies, S.; Thissen, P.; Tabatabai, D.; Feil, F.; Fürbeth, W.; Fink, N.; Grundmeier, G. Formation and Stability of Organic Acid Monolayers on Magnesium Alloy AZ31: The Role of Alkyl Chain Length and Head Group Chemistry. Appl. Surf. Sci. 2013, 283, 339− 347. (72) Quiñones, R.; Rodriguez, K.; Iuliucci, R. J. Investigation of Phosphonic Acid Surface Modifications on Zinc Oxide Nanoparticles Under Ambient Conditions. Thin Solid Films 2014, 565, 155−164. (73) Lewington, T. A.; Alexander, M. R.; Thompson, G. E.; McAlpine, E. bodycote International Prize Paper Competition: Shortlisted Characterisation of Alkyl Phosphonic Acid Monolayers Self Assembled on Hydrated Surface of Aluminium. Surf. Eng. 2002, 18, 228−232. (74) Snyder, R. G.; Hsu, S. L.; Krimm, S. Vibrational Spectra in the C−H Stretching Region and the Structure of the Polymethylene Chain. Spectrochim. Acta, Part A 1978, 34, 395−406. (75) MacPhail, R. A.; Strauss, H. L.; Snyder, R. G.; Elliger, C. A. Carbon-Hydrogen Stretching Modes and the Structure of n-Alkyl Chains. 2. Long, All-Trans Chains. J. Phys. Chem. 1984, 88, 334−341. (76) Nuzzo, R. G.; Fusco, F. A.; Allara, D. L. Spontaneously Organized Molecular Assemblies. 3. Preparation and Properties of Solution Adsorbed Monolayers of Organic Disulfides on Gold Surfaces. J. Am. Chem. Soc. 1987, 109, 2358−2368. (77) Laibinis, P. E.; Whitesides, G. M.; Allara, D. L.; Tao, Y.-T.; Parikh, A. N.; Nuzzo, R. G. Comparison of the Structures and Wetting Properties of Self-Assembled Monolayers of n-Alkanethiols on the Coinage Metal Surfaces, Cu, Ag, Au. J. Am. Chem. Soc. 1991, 113, 7152−7167. (78) Porter, M. D. IR External Reflection Spectroscopy: A Probe for Chemically Modified Surfaces. Anal. Chem. 1988, 60, 1143A−1155A. (79) Porter, M. D.; Bright, T. B.; Allara, D. L.; Chidsey, C. E. D. Spontaneously Organized Molecular Assemblies. 4. Structural Characterization of n-Alkyl Thiol Monolayers on Gold by Optical Ellipsometry, Infrared Spectroscopy, and Electrochemistry. J. Am. Chem. Soc. 1987, 109, 3559−3568. (80) Levine, I.; Weber, S. M.; Feldman, Y.; Bendikov, T.; Cohen, H.; Cahen, D.; Vilan, A. Molecular Length, Monolayer Density, and

Charge Transport: Lessons from Al-AlOx/Alkyl−Phosphonate/Hg Junctions. Langmuir 2012, 28, 404−415. (81) Gao, W.; Dickinson, L.; Grozinger, C.; Morin, F. G.; Reven, L. Self-Assembled Monolayers of Alkylphosphonic Acids on Metal Oxides. Langmuir 1996, 12, 6429−6435. (82) Steiner, G.; Sablinskas, V.; Kitsche, M.; Salzer, R. Polarization Modulation-Infrared Reflection Absorption Spectroscopic Mapping. Anal. Chem. 2006, 78, 2487−2493. (83) Botelho do Rego, A. M.; Ferraria, A. M.; El Beghdadi, J.; Debontridder, F.; Brogueira, P.; Naaman, R.; Rei Vilar, M. Adsorption of Phenylphosphonic Acid on GaAs (100) Surfaces. Langmuir 2005, 21, 8765−8773. (84) Gleskova, H.; Gupta, S.; Šutta, P. Structural Changes in VapourAssembled n-Octylphosphonic Acid Monolayer with Post-Deposition Annealing: Correlation with Bias-Induced Transistor Instability. Org. Electron. 2013, 14, 3000−3006. (85) D’Andre, S. C.; Fadeev, A. Y. Covalent Surface Modification of Calcium Hydroxyapatite Using n-Alkyl- and n-Fluoroalkylphosphonic Acids. Langmuir 2003, 19, 7904−7910. (86) Wilson, J. The Normal Modes and Frequencies of Vibration of the Regular Plane Hexagon Model of the Benzene Molecule. Phys. Rev. 1934, 45, 706−714. (87) Acton, B. O.; Ting, G. G.; Shamberger, P. J.; Ohuchi, F. S.; Ma, H.; Jen, A. K. Y. Dielectric Surface-Controlled Low-Voltage Organic Transistors via n-Alkyl Phosphonic Acid Self-Assembled Monolayers on High-k Metal Oxide. ACS Appl. Mater. Interfaces 2010, 2, 511−520. (88) Gudipati, M. S.; Hamrock, S. J.; Balaji, V.; Michl, J. Infrared Spectra of [n]staffanes. J. Phys. Chem. 1992, 96, 10165−10176. (89) Jordanov, B.; Tsankov, D.; Korte, E. H. Peculiarities in the Stretching Vibrations of the Methylene Groups. J. Mol. Struct. 2003, 651−653, 101−107. (90) Rong, Z.; Lespade, L.; Cavagnat, D. Vibrational Overtones of Some Deuterated Propanes: the Methylene Chromophore. J. Mol. Struct. 2005, 752, 45−53. (91) Sibert, E. L.; Tabor, D. P.; Kidwell, N. M.; Dean, J. C.; Zwier, T. S. Fermi Resonance Effects in the Vibrational Spectroscopy of Methyl and Methoxy Groups. J. Phys. Chem. A 2014, 118, 11272−11281. (92) Rajalingam, K.; Hallmann, L.; Strunskus, T.; Bashir, A.; Wöll, C.; Tuczek, F. Self-Assembled Monolayers of Benzylmercaptan and ParaCyanobenzylmercaptan on Gold: Surface Infrared Spectroscopic Characterization. Phys. Chem. Chem. Phys. 2010, 12, 4390−4399. (93) Niklewski, A.; Azzam, W.; Strunskus, T.; Fischer, R. A.; Wöll, C. Fabrication of Self-Assembled Monolayers Exhibiting a ThiolTerminated Surface. Langmuir 2004, 20, 8620−8624. (94) Balfour, W. J. The Vibrational Spectrum of Anisole. Spectrochim. Acta, Part A 1983, 39, 795−800. (95) Pawsey, S.; Yach, K.; Reven, L. Self-Assembly of Carboxyalkylphosphonic Acids on Metal Oxide Powders. Langmuir 2002, 18, 5205−5212. (96) Luschtinetz, R.; Oliveira, A. F.; Frenzel, J.; Joswig, J. O.; Seifert, G.; Duarte, H. A. Adsorption of Phosphonic and Ethylphosphonic Acid on Aluminum Oxide Surfaces. Surf. Sci. 2008, 602, 1347−1359. (97) Di Valentin, C.; Costa, D. Anatase TiO2 Surface Functionalization by Alkylphosphonic Acid: A DFT+D Study. J. Phys. Chem. C 2012, 116, 2819−2828. (98) Thissen, P.; Vega, A.; Peixoto, T.; Chabal, Y. J. Controlled, LowCoverage Metal Oxide Activation of Silicon for Organic Functionalization: Unraveling the Phosphonate Bond. Langmuir 2012, 28, 17494− 17505. (99) Smecca, E.; Motta, A.; Fragalà, M. E.; Aleeva, Y.; Condorelli, G. G. Spectroscopic and Theoretical Study of the Grafting Modes of Phosphonic Acids on ZnO Nanorods. J. Phys. Chem. C 2013, 117, 5364−5372. (100) Fonder, G.; Delhalle, J.; Essahli, M.; Ameduri, B.; Mekhalif, Z. Anchoring of Sulfur-Containing Alkylphosphonic and Semifluorinated Alkylphosphonic Molecules on a Polycrystalline Aluminum Substrate. Surf. Interface Anal. 2008, 40, 85−96. (101) Paniagua, S. A.; Giordano, A. J.; Smith, O. L.; Barlow, S.; Li, H.; Armstrong, N. R.; Pemberton, J. E.; Brédas, J. L.; Ginger, D.; M

DOI: 10.1021/acs.jpcc.6b11089 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C Marder, S. R. Phosphonic Acids for Interfacial Engineering of Transparent Conductive Oxides. Chem. Rev. 2016, 116, 7117−7158. (102) Wagstaffe, M.; Thomas, A. G.; Jackman, M.; Torres-Molina, M.; Syres, K. L.; Handrup, K. An Experimental Investigation of the Adsorption of a Phosphonic Acid on the Anatase TiO2(101) Surface. J. Phys. Chem. C 2016, 120, 1693−1700. (103) Brodard-Severac, F.; Guerrero, G.; Maquet, J.; Florian, P.; Gervais, C.; Mutin, P. H. High-Field 17O MAS NMR Investigation of Phosphonic Acid Monolayers on Titania. Chem. Mater. 2008, 20, 5191−5196. (104) Guerrero, G.; Mutin, P. H.; Vioux, A. Anchoring of Phosphonate and Phosphinate Coupling Molecules on Titania Particles. Chem. Mater. 2001, 13, 4367−4373.

N

DOI: 10.1021/acs.jpcc.6b11089 J. Phys. Chem. C XXXX, XXX, XXX−XXX