An STM/FM-AFM investigation of selected organic and inorganic 2D systems on metallic surfaces

• Autores: Sonia Matencio Lloberas
• Directores de la Tesis: Esther Barrena Villas (dir. tes.), Elisa Vallés Giménez (dir. tes.), Carmen Ocal Garcia (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2015
• Idioma: inglés
• Tribunal Calificador de la Tesis: Francesc Mas (presid.), Marta Mas Torrent (secret.), Carlos Escudero Rodríguez (voc.)
• Materias:
  • Física
    • Física del estado sólido
      • Interfases
      • Superficies
  • Química
    • Química analítica
      • Microscopia
• Enlaces
  • Tesis en acceso abierto en: Dipòsit Digital de la UB
• Resumen

  • Organic/inorganic interfaces play a key role in organic electronic devices such as organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). In these interfaces crucial processes such as charge injection or extraction take place. Improving the performance of these devices has the potential to result in more efficient sources of lighting, printable electronics, and highly scalable solar energy harvesting. With this aim, a solid understanding at atomic level of the structural and electronic properties of organic/inorganic interfaces is needed. The research presented in this thesis is based on scanning probe microscopies which are powerful techniques to probe and manipulate the electronic and structure at atomic scale. The structural and electronic properties of selected organic and inorganic 2D systems on metallic surfaces have been investigated by a combined scanning tunneling microscopy (STM) and frequency modulation atomic force microscopy (FM-AFM) in ultra-high vacuum conditions and at room temperature. The combination of these local probe techniques permits elucidating the interface structure at atomic level and disentangle electronic from topographic information. Cuprous oxide (Cu2O) is an intrinsic p-type semiconductor. Copper oxide ultrathin films have been suggested to be candidates for uses as low resistance electrodes, catalysts, sensing materials and semiconductor materials for solar cell transformation. But the properties of this ultrathin film may differ from the bulk properties. With the aim of increase the actual knowledge, an atomic thin film of copper oxide has been grown on Cu(111). Several organic molecules have been tested on different surfaces: perylene-3,4,9,10-tetracarboxylic anhydride (PTCDA) on Si(111)7x7 and AgSi(111), diindenoperylene (DIP) on Cu(111) and chloroaluminum phthalocyanine (ClAlPc) on Au(111). All of them are small pi-conjugate molecules that have been grown by molecular beam deposition. The final structure of these molecules on the surfaces is a competition between intermolecular and molecule-substrate forces. The perylene derivatives DIP and PTCDA are served as model systems for a basic understanding of organic/inorganic interfaces and the ClAlPc are used to study the influence of a dipolar molecule. In the organic/metal interface many complex processes can occur such as charge transfer, charge rearrangement and push back effect, affecting the work function change in a non trivial way.