TY - JOUR

T1 - Unoccupied Electron States of Ultrathin Films of Thiophene–Phenylene Cooligomers on the Surface of Polycrystalline Gold

AU - Komolov, A. S.

AU - Lazneva, E. F.

AU - Gerasimova, N. B.

AU - Sobolev, V. S.

AU - Pshenichnyuk, S. A.

AU - Borshchev, O. V.

AU - Ponomarenko, S. A.

AU - Handke, B.

N1 - Funding Information: This work was supported by the Russian Foundation for Basic Research, projects nos. 18-03-00020 and 18-03-00179. The synthesis of CH–PTTP–CH was supported by the Ministry of Science and Higher Education of the Russian federation in the framework of state task to the Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences. The studies of ZnO layers were supported by the Russian Foundation for Basic Research, project no. 20-03-00026. 3 3 ACKNOWLEDGMENTS Publisher Copyright: © 2020, Pleiades Publishing, Ltd. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/10/1

Y1 - 2020/10/1

N2 - Unoccupied electronic states in the energy range from 5 to 20 eV above the Fermi level have been studied in ultrathin films of dimethyl-substituted thiophene-phenylene cooligomers CH3-phenylene-thiophene-thiophene-phenylene-CH3 (CH3-PTTP-CH3) on polycrystalline gold surfaces of two types: the ex situ Au layer thermally deposited in a special chamber and the in situ Au surface prepared inside an analytical chamber. The film structure is studied by the X-ray diffraction (XRD) method. The formation of a superposition of the amorphous phase and the crystalline phase with period 3.8 nm is discussed. The energy positions of the maxima of the unoccupied electronic states and the character of formation of the boundary potential barrier have been studied by the total current spectroscopy (TCS). The structures of the FSTCS maxima of the 5-7-nm-thick CH3-PTTP-CH3 films are not different when using various types of Au substrates and the ZnO semiconductor surface prepared by atomic layer deposition (ALD). As a CH3-PTTP-CH3 layer is deposited on the ex situ Au and in situ Au surfaces, the electron work function increases insignificantly (by similar to 0.1 eV) as the coating thickness increases to 5-7 nm. At such thicknesses of the CH3-PTTP-CH3 films, the electron work function is 4.7 +/- 0.1 eV in the case of the ex situ Au substrate and 4.9 +/- 0.1 eV in the case of the in situ Au substrate. A possible influence of the processes of physicochemical interaction at the boundary between the film and the substrate on the formation of the boundary potential barrier in the structures under study is discussed.

AB - Unoccupied electronic states in the energy range from 5 to 20 eV above the Fermi level have been studied in ultrathin films of dimethyl-substituted thiophene-phenylene cooligomers CH3-phenylene-thiophene-thiophene-phenylene-CH3 (CH3-PTTP-CH3) on polycrystalline gold surfaces of two types: the ex situ Au layer thermally deposited in a special chamber and the in situ Au surface prepared inside an analytical chamber. The film structure is studied by the X-ray diffraction (XRD) method. The formation of a superposition of the amorphous phase and the crystalline phase with period 3.8 nm is discussed. The energy positions of the maxima of the unoccupied electronic states and the character of formation of the boundary potential barrier have been studied by the total current spectroscopy (TCS). The structures of the FSTCS maxima of the 5-7-nm-thick CH3-PTTP-CH3 films are not different when using various types of Au substrates and the ZnO semiconductor surface prepared by atomic layer deposition (ALD). As a CH3-PTTP-CH3 layer is deposited on the ex situ Au and in situ Au surfaces, the electron work function increases insignificantly (by similar to 0.1 eV) as the coating thickness increases to 5-7 nm. At such thicknesses of the CH3-PTTP-CH3 films, the electron work function is 4.7 +/- 0.1 eV in the case of the ex situ Au substrate and 4.9 +/- 0.1 eV in the case of the in situ Au substrate. A possible influence of the processes of physicochemical interaction at the boundary between the film and the substrate on the formation of the boundary potential barrier in the structures under study is discussed.

KW - atomic layer deposition method

KW - electronic properties

KW - low-energy electron spectroscopy

KW - polycrystalline Au surface

KW - thiophene–phenylene cooligomers

KW - ultrathin films

KW - X-ray diffraction method

KW - ZnO

KW - OXIDE

KW - DEPOSITION

KW - GRAPHENE

KW - MONOLAYERS

KW - COMPOSITE FILMS

KW - PERYLENE

KW - thiophene-phenylene cooligomers

KW - INTERFACE

KW - THIOPHENE/PHENYLENE CO-OLIGOMERS

KW - ENERGY-LEVEL ALIGNMENT

UR - http://www.scopus.com/inward/record.url?scp=85092396992&partnerID=8YFLogxK

U2 - 10.1134/S1063783420100170

DO - 10.1134/S1063783420100170

M3 - Article

AN - SCOPUS:85092396992

VL - 62

SP - 1960

EP - 1966

JO - Physics of the Solid State

JF - Physics of the Solid State

SN - 1063-7834

IS - 10

ER -