PhD Thesis Defence Presentations - Charalampos Drivas

Presentation Title (Τίτλος Παρουσίασης): Study of the interfaces of organic semiconductors and layered materials with surface sensitive techniques for applications in organic electronics
Presentation Type (Τύπος Παρουσίασης): PhD Thesis Defence Presentations
Speakers Full Name (Ονοματεπώνυμο): Charalampos Drivas
Speakers Affiliation (Προέλευση Ομιλητή): University of Patras, Department of Chemical Engineering
Seminar Room (Αίθουσα): Webinar Only
Event Date: Wed, Jun 11 2025, Time: 14:00 - 16:00
Live webConference Link: https://upatras-gr.zoom.us/j/92691299058?pwd=tg5gUT89C4Tv0eEMSxsRbYL2sjc4Xe.1
Abstract (Περίληψη)

This dissertation focuses on the study of interfaces between organic semiconductors and transition metal dichalcogenides (TMDs), with the aim of understanding their electronic properties for applications in organic electronics. The research is based on surface-sensitive spectroscopic techniques — X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS) — to investigate energy level alignment and charge transfer at the interfaces.

The dissertation begins with a theoretical introduction to the properties of TMDs, their structure, and some of their electronic characteristics. In parallel, the properties of organic semiconductors and the importance of their molecular structure for energy level alignment and efficient charge transport at the interfaces with TMDs are examined.

The experimental section includes the in-situ deposition of organic molecules P3HT, H₂Pc, MnPc, and CuPc on 2H-MoS₂(0001), 2H-TaS₂(0001), and CVD-grown 2H-MoS₂ substrates. For the P3HT/MoS₂ interface, in addition to the electronic properties, the effect of substrate treatment on these properties is studied. It was found that thermal treatment of the MoS₂ single crystal affects the Fermi level of the material, which in turn influences the potential barriers with P3HT.

Regarding the metal phthalocyanines, a significant part of the research focuses on the role of the metal centre in facilitating charge transfer to and from the substrate. Experimental results show that the central metal atom in the molecule acts as a channel for charge transfer, with this effect being most pronounced in copper, even influencing the molecular ring. Differences were observed between single-crystal and CVD-MoS₂ in terms of charge transfer to the substrate. Although electron transfer phenomena were strong in the single crystal, the presence of defects and S-rich edges reduces these effects. The results from the deposition of phthalocyanines on the 2H-TaS₂ substrate showed similar behaviour to that observed on 2H-MoS₂, despite significant differences in the electronic properties of the two materials. Additionally, no chemical bond formation or structural alteration of the phthalocyanine molecule was observed, as is often the case with conventional metals, which supports the use of metallic TMDs as electrodes in metal–organic contacts.

Finally, the energy level diagrams of all studied interfaces were determined, which are essential for applying these systems in microelectronic devices. From the energy diagrams, the electron and hole barriers were calculated, as these define the performance of a device.

Overall, the dissertation provides clear evidence that the targeted design of organic–TMD heterostructures with desirable electronic properties is feasible without the need for chemical modification of the TMDs. These findings are particularly important for the development of new low-cost, flexible, and functional electronic and optoelectronic devices, such as organic field-effect transistors, photodetectors, and memory elements.

 

The advisory committee:

Georgios Kyriakou (Supervisor), Professor, Department of Chemical Engineering, University of Patras
Dimitris Kouzoudis, Professor, Department of Chemical Engineering, University of Patras
Leonidas Palilis, Professor, Department of  Physics, University of Patras

Speakers Short CV (Σύντομο Βιογραφικό Ομιλητή)

Work experience:

  • Postdoctoral Research Associate, Cardiff University - UK Catalysis HUB (2023-2024)
    Synchrotron Methods In Catalysis
  • Postdoctoral Research Associate,  The University of Manchester - UK Catalysis HUB - Harwell XPS (2022-2023)
    Operando X-ray photoelectron spectroscopy at the solid-liquid interface
  • Teaching assistant,  Department of Chemical Engineering, University of Patras (2016-2022)
    Materials Science & Physics Laboratory

Education:

  • PhD Candidate, Department of Chemical Engineering, University of Patras  (2018-2025)
     Study of the interfaces of organic semiconductors and layered materials with surface sensitive techniques for applications in organic electronics
  • Master of Engineering, Department of Chemical Engineering, University of Patras(2016-2018)
    Determination of the chemical composition and electronic structure of oxide thin films with applications in microelectronic devices by photoelectron spectroscopies 
  • Bachelor's Degree, Department of Materials Science, University of Patras (2010-2015)
    Synthesis and characterisation of superconducting materials

Honours and Awards:

  • Best poster award, Harwell XPS Thematic Summer School 2024
    Considerations on the XPS analysis of 2H-TaS2
  • Scholar of the 2nd call for H.F.R.I Scholarships to PhD Candidates
  • Scholar of the 44th Regular Scholarship Programme for Postgraduate Studies of the Bodossaki Foundation
  • Awards of excellence by the Limmat Foundation, Switzerland, for Postgraduate Studies
  • Bachelor's Degree with honours

Conferences and Seminars: 

  •  C.Drivas, G.Kyriakou, C.R.A.Catlow, M.A.Isaacs, Considerations on the XPS analysis of 2H-TaS2 (0001)
    Harwell XPS Thematic Summer School 2024, Cardiff, UK, 09/09/24-13/09/24
  • C.Drivas, E.Jones, R.Weatherup, M.Isaacs, C.Parlett, Operando X-ray photoelectron spectroscopy at the solid-liquid interface
    10th UK Catalysis Conference (UKCC), Loughborough, UK, 03/01/24-05/01/24
  • C.Drivas, M.A.Isaacs, C.M.A.Parlett, Decoration of zirconium oxide nanoparticles with tungsten oxide for fructose dehydration
    SCI Catalysis for Sustainable Future, London, UK, 14/06/23
  • C.Drivas, S.Kennou, Electronic properties of the interfaces between Cu-phthalocyanine and 2H-MoS2 and 2H-TaS2 single crystals
    5th International Conference on Applied Surface Science, Mallorca, Spain, 25/04/22-28/04/22
  • C.Drivas, F.Iacovella, G.Deligeorgis, S.Kennou, Comparative study of the electronic structure of poly(3-hexylthiophene) / MoS2 interfaces by photoelectron spectroscopies
    4th International Conference on Applied Surface Science, London, UK, 28/06/21-29/06/21
  • C.Drivas, F.Iacovella, G.Deligeorgis, S.Kennou, In situ study of poly(3-hexylthiophene) / MoS2 interface by photoelectron spectroscopies
    35th Panhellenic Conference on Solid State Physics and Materials Science, Athens, Greece, 26/9/21-29/09/21
  • C.Drivas, S.Kennou, An interface study of the oligomer P3HT on the basal plane of MoS2 by photoelectron spectroscopies
    34th Panhellenic Conference on Solid State Physics and Materials Science, Patras, Greece, 11/09/19-14/09/19
  • C.Drivas, C.Alexopoulou, A.Petala, Z.Frontistis, D.I.Kondarides, D.Mantzavinos, S.Kennou, X-ray Photoelectron Spectroscopy (XPS): A complementary technique for material characterisation, insight into the copper (I) phosphide catalyst
    9th International Conference of the Hellenic Crystallographic Association, Patras, Greece, 05/10/18-7/10/18
  • C.Drivas, M.A.Botzakaki, S.N.Georga, C.A.Krontiras, S.Kennou, Synthesis of Ultra-Thin Oxide Films Interfaces. Determination of their Chemical Composition and the Band Bending
    11th Panhellenic Scientific Conference on Chemical Engineering, Thessaloniki, Greece, 25/06/17-28/06/17

Selected Publications:
           Overview: 33 publications, 1018 citations, h-index 17, Google Scholar

  •  C. Drivas, S. Kennou, G. Kyriakou, Phthalocyanine interfaces with MoS2 (0001): The effect of the metal centre on the charge transfer, Appl Surf Sci  682 (2025) 161672. https://doi.org/10.1016/j.apsusc.2024.161672 
  • E.S. Jones, C. Drivas, J.S. Gibson, J.E.N. Swallow, L.A.H. Jones, T.D.J. Bricknell, M.A. van Spronsen, G. Held, M.A. Isaacs, C.M.A. Parlett, R.S. Weatherup, In Situ Formation of Suspended Graphene Windows for Lab‐Based XPS in Liquid and Gas Environments, ChemCatChem  16 (2024). https://doi.org/10.1002/cctc.202400239 
  • M.A. Isaacs, C. Drivas, R. Lee, R. Palgrave, C.M.A. Parlett, D.J. Morgan, XPS surface analysis of ceria-based materials: Experimental methods and considerations, Applied Surface Science Advances  18 (2023) 100469. https://doi.org/10.1016/j.apsadv.2023.100469 
  • C. Drivas, F. Iacovella, G. Deligeorgis, S. Kennou, Electronic properties of the Poly(3-hexylthiophene) / MoS2 interfaces: The influence of the substrate, Appl Surf Sci  572 (2022) 151372. https://doi.org/10.1016/j.apsusc.2021.151372 
  • C. Drivas, M.A. Botzakaki, S.N. Georga, C.A. Krontiras, S. Kennou, Interface band offset determination of ultra-thin oxides grown on TiO2 and ZnO by x-ray photoelectron spectroscopy, J Phys D Appl Phys 54 (2021) 285301. https://doi.org/10.1088/1361-6463/abf9db 
  • S. Korkos, N.J. Xanthopoulos, M.A. Botzakaki, C. Drivas, S. Kennou, S. Ladas, A. Travlos, S.N. Georga, C.A. Krontiras, XPS analysis and electrical conduction mechanisms of atomic layer deposition grown Ta2O5 thin films onto p-Si substrates, Journal of Vacuum Science & Technology A 38 (2020) 032402. https://doi.org/10.1116/1.5134764