Low-energy electron transmission for the analysis
of the interface barrier formation and the density
of the unoccupied electronic states in the
ultra-thin layers of fluorinated
copper-phthalocyanine

• Authors: A. S. Komolov , E. F. Lazneva , S. N. Akhremtchik , N. B. Gerasimova , S. A. Pshenichnyuk
• Languages of publication: EN

Abstracts

EN

The interfacial structure made from the thermally
deposited 5 – 7 nm thick layers of hexadecafluoro
copper phthalocyanine (F16-CuPc) and of the unsubstituted
copper phthalocyanine (CuPc) was subjected
to the studies. The surface work function and the density
of the unoccupied electron states (DOUS) located 5-
20 eV above the Fermi level (EF) were investigated during
the CuPc/F16-CuPc interface formation using the very
low energy electron diffraction (VLEED) method and the
total current spectroscopy (TCS) measurement scheme.
The DOUS peak structure of the organic films studied obtained
from the TCS results showed a good correspondence
to the main π* and σ* DOUS bands obtained from
the density functional theory (DFT) calculations. The interfacial
barrier was characterized by the negative charge
transfer from the CuPc overlayer to the F16-CuPc underlayer
occurred within the 5 nm thick interfacial region in
the CuPc overlayer which was accompanied by the decrease
of the surface work function from 4.9±0.1 eV to
4.3±0.1 eV. The stabilization of the π* DOUS bands, as
well as restructuring of the low lying σ* bands was observed
in the in the case of the fluorinated film (F16-
CuPc) compared to the case of the unsubstituted CuPc film.

Keywords

EN

Organic semiconducting films; Surface electronicphenomena (work function, surface potential, surfacestates, etc.); interface charge transfer; DFT calculations; Density of states

• Publisher: De Gruyter Open
• Journal: Organic Photonics and Photovoltaics
• Year: 2015
• Volume: 3
• Issue: 1

Dates

received

1 - 9 - 2014

accepted

19 - 12 - 2014

online

29 - 1 - 2015

Contributors

author

A. S. Komolov

author

E. F. Lazneva

author

S. N. Akhremtchik

author

N. B. Gerasimova

author

S. A. Pshenichnyuk

References

• [1] J. Jo, J.-R. Pouliot, D.Wynands, S.D. Collins, J.Y. Kim, T.L. Nguyen,H.Y. Woo, Y. Sun, M. Leclerc and A.J. Heeger, Enhanced Eflciencyof Single and Tandem Organic Solar Cells Incorporating aDiketopyrrolopyrrole-Based Low-Bandgap Polymer by UtilizingCombined ZnO/Polyelectrolyte Electron-Transport Layers, Adv.Mater. 25(34), 2013, 4783.[WoS]
• [2] A.N. Aleshin, I.P. Sherbakov, V.N. Petrov and A.N. Titkov,Solution-processed polyfluorene–ZnOnanoparticlesambipolarlight-emitting field-effect transistor, Organic Electr. 12, 2011,1285.
• [3] S. M. Yoon, S. J. Lou, S. Loser, J. Smith, L. X. Chen, A. Facchettiand T. J. Marks, Fluorinated Copper Phthalocyanine Nanowiresfor Enhancing Interfacial Electron Transport in Organic SolarCells, Nano Lett. 12(12), 2012, 6315.[Crossref][WoS]
• [4] A. Y. Sosorev, O. D. Parashchuk, S. A. Zapunidi, G. S. Kashtanovand D. Y. Paraschuk, Intrachain Aggregation of Charge-Transfer Complexes in Conjugated Polymer: Acceptor Blendsfrom Photoluminescence Quenching, J. Phys. Chem. C, 117(14),2013, 6972.[WoS]
• [5] J. Min, H. Zhang, T. Stubhan, Y.N. Luponosov, M. Kraft, S.A.Ponomarenko, T. Ameri, U. Scherf and C. J. Brabec. A combinationof Al-doped ZnO and a conjugated polyelectrolyte interlayerfor small molecule solution-processed solar cells with aninverted structure, J. Mater. Chem. A 1(37), 2013, 11306.[WoS]
• [6] L. Grządziel, M. Krzywiecki, H. Peisert, T. Chassé and J. Szuber,Photoemission study of the Si(1 1 1)-native SiO2/copperphthalocyanine (CuPc) ultra-thin film interface, Organic Electr.13(10), 2012, 1873.
• [7] Y. Gao, Surface analytical studies of interfaces in organic semiconductordevices, Materials Science and Engineering R: Reports68(3), 2010, 39.
• [8] J. L. Brédas and A. J. Heeger, Influence of Donor andAcceptor Substituents on the Electronic Characteristics ofPoly(Paraphenylene Vinylene) and Poly(Paraphenylene), Chem.Phys. Lett. 217, 1994, 507.
• [9] F. Babudri, G. M. Farinola, F. Naso and R. Ragni, Fluorinated OrganicMaterials for Electronic and Optoelectronic Applications:The Role of the Fluorine Atom, Chem. Comm. 10, 2007, 1003.[Crossref]
• [10] J. Cornil, D. A. Dos Santos, D. Beljonne and J. L. Bredas, ElectronicStructure of Phenylene Vinylene Oligomers: Influence ofDonor/Acceptor Substitutions, J. Phys. Chem. 99, 1995, 5604.
• [11] Y. Fu, W. Shen and M Li, Theoretical Analysis on the ElectronicStructures and Properties of PPV Fused with Electron-Withdrawing Unit: Monomer, Oligomer and Polymer, Polymer49, 2008, 2614.[WoS]
• [12] A. P. Hitchcock, P. Fischer, A. Gedanken and M. B. Robin, AntibondingSigma* ValenceMOs in the Inner-Shell and Outer-ShellSpectra of the Fluorobenzenes, J. Phys. Chem. 91, 1987, 531.
• [13] R. Dudde, B. Reihl and A. Otto, π* and σ* molecular orbitalsof condensed films of chlorobenzenes and hexafluorobenzeneobserved by inverse photoemission J. Chem. Phys. 92(6), 1990,3930.
• [14] A. Modelli, Electron Attachment and Intramolecular ElectronTransfer in Unsaturated Chloroderivatives, Phys. Chem. Chem.Phys. 5, 2003, 2923.[Crossref]
• [15] S. A. Pshenichnyuk, N. L. Asfandiarov and P. D. Burrow, A RelationBetween Energies of the Short-Lived Negative Ion Statesand Energies of Unfilled Molecular Orbitals for a Series of Bromoalkanes,Russ. Chem. Bull., Int. Ed. 56, 2007, 1268.[WoS]
• [16] A. S. Komolov, P. J. Møller and E. F. Lazneva, Interface FormationBetween Oligo(Phenylele–Vinylene) Films and Highly OrderedPyrolytic Graphite and Ge(1 1 1) Surfaces, J. Electron Spectr. Rel.Phenom. 131-132, 2003, 67.
• [17] A. S. Komolov, E. F. Lazneva, S. N. Akhremtchik, N. S. Chepilkoand A. A. Gavrikov, Unoccupied Electronic States at the Interfaceof Oligo(phenylene-vinylene) Films with Oxidized Silicon,J. Phys. Chem. C, 117(24), 2013, 12633.
• [18] J. Ren, Sh. Meng, Y-L. Wang, X-C. Ma, Q-K. Xue and E. Kaxiras,Properties of Copper (Fluoro) Phthalocyanine Layers Depositedon Epitaxial Graphene, J. Chem. Phys. 134, 2011, 194706.
• [19] S. Godlewski, A. Tekiel, J.S. Prauzner-Bechcicki, J. Budzioch, A.Gourdon and M. Szymonski, Adsorption of organicmolecules onthe TiO2(011) surface: STM study, J. Chem. Phys. 134(22), 2011,224701.
• [20] A. Opitz, B. Ecker, J. Wagner, A. Hinderhofer, F. Schreiber, J.Manara, J. Pflaum and W. Brütting, Mixed crystalline films ofco-evaporated hydrogen- and fluorine-terminated phthalocyaninesand their application in photovoltaic devices, OrganicElectr. 10, 2009, 1259.
• [21] A. S. Komolov, P. J. Møller, J. Mortensen, S. A. Komolov and E. F.Lazneva, Modification of the electronic properties of the TiO2 (11 0) surface upon deposition of the ultrathin conjugated organiclayers, Appl. Surf. Sci. 253, 2007, 7376.
• [22] A. S. Komolov, S. A. Komolov, E. F. Lazneva, A. A. Gavrikov and A.M. Turiev, Electronic properties of the polycrystalline tin dioxideinterface with conjugated organic layers, Surf. Sci. 605, 2011,1449.
• [23] A. S. Komolov, E. F. Lazneva, S. A. Pshenichnyuk, A. A. Gavrikov,N. S. Chepilko, A. A. Tomilov, N. B. Gerasimova, A. A. Lezov andP. S. Repin, Electronic properties of the interface between hexadecafluorocopper phthalocyanine and unsubstituted copperphthalocyanine films, Semiconductors 47(7), 2013, 956.[WoS][Crossref]
• [24] I. Bartos, Electronic structure of crystals via VLEED, Progr. Surf.Sci. 59, 1998, 197.
• [25] S.A. Pshenichnyuk and A.S.Komolov, Relation between ElectronScattering Resonances of Isolated NTCDA Molecules and Maximain the Density of Unoccupied States of Condensed NTCDALayers, J. Phys. Chem. A 116 (1), 2012, 761.[WoS]
• [26] M. J. Frisch, G.W. Trucks, H. B. Schlegel et al., Gaussian 03.D.01,Gaussian Inc. Wallingford CT, 2004.
• [27] A. D. Becke, Density functional thermochemistry. III. The role ofexact exchange, J. Chem. Phys. 98, 1993, 5648.
• [28] I. G. Hill, A. Kahn, J. Cornil, D.A. dos Santos and J.L. Bredas,Occupied and unoccupied electronic levels in organic piconjugatedmolecules: comparison between experiment andtheory, Chem. Phys. Lett. 317, 2000, 444.
• [29] P. D. Burrow and A. Modelli, On the treatment of LUMO energiesfor their use as descriptors, SAR and QSAR in Env. Res. 24(8),2013, 647.[WoS]
• [30] A. Modelli and S.A. Pshenichnyuk, Empty-Level Structure andReactive Species Produced by Dissociative Electron Attachmentto Tert -Butyl Peroxybenzoate, J. Phys. Chem. A 116(14), 2012,3585.
• [31] A. M. Scheer and P. D. Burrow, π* Orbital System of AlternatingPhenyl and Ethynyl Groups: Measurements and Calculations, J.Phys. Chem. B 110(36), 2006, 17751.
• [32] S. A. Pshenichnyuk, A. V. Kukhto, I.N. Kukhto and A. S. Komolov,Spectroscopic States of PTCDA Negative Ions and Their Relationto the Maxima of Unoccupied State Density in the ConductionBand, Technical Phys. 56, 2011, 754.[WoS]
• [33] A. S. Komolov, S. N. Akhremtchik and E. F. Lazneva, Spectrochim.Acta A 798, 2011, 708.
• [34] H. Yoshida, K. Tsutsumi and N. Sato, Unoccupied electronicstates of 3d-transition metal phthalocyanines (MPc: M=Mn, Fe,Co, Ni, Cu and Zn) studied by inverse photoemission spectroscopy,J. El. Spectr. Rel. Phen. 121, 2001, 83.
• [35] H. Peisert, T. Schwieger, J. M. Auerhammer, M. Knupfer, M. S.Golden, J. Fink, P. R. Bressler and M. Mast, Order on disorder:Copper phthalocyanine thin films on technical substrates, J.Appl. Phys. 90(1) 2001, 466.[Crossref]
• [36] M. Rocco, K. Frank, P. Yannoulis and E. Koch, Unoccupied electronicstructure of phthalocyanine films. J. Chem. Phys. 93(9),1990, 6859.

Identifiers

DOI

10.1515/oph-2015-0002