| | | | | | | webmail : intra-extra| Accès VPN| Accès IST| Contact | Français
Organics on Surfaces: Energy Level Alignment, Charging Energy and Theoretical STM
 
Dept. de Superficies y Recubrimientos (ICMM / CSIC), ES-28049 Madrid, Spain
Fri, Jun. 07th 2013, 11:00-12:30
SPEC Bât 466 p.111 (1er ét.), CEA-Saclay

invited by Yannick DAPPE

Abstract :

Understanding the interaction between organic molecules and metal surfaces is of paramount importance in diverse fields such as organic electronics, molecular electronics, catalysis, surface photochemistry, among others. In particular, the growing field of organic electronics relies on the use of organic conjugated molecules as components of multilayer devices. The performance of these devices depends critically on the energy barriers that control the carrier transport between layers, energy barriers that are determined by the relative alignment of the molecular levels at substrate–organic (MO) or organic–organic (OO) interfaces. It has been suggested that the tendency of the Charge Neutrality Level (CNL) of the organic material to align with the interface Fermi level plays a crucial role; this mechanism is associated with the induced density of interface states (IDIS) in the organic gap and the charge transfer between the organic and the substrate. More recently, this model has been extended to the Unified IDIS model by inclusion of Pauli repulsion and intrinsic molecular dipoles. On the basis of the Unified IDIS model, we have investigated the interaction of a variety of organic molecules such as Bz [1a], TTF [1b], TCNQ [1c], PTCDA [1d, 1e], and some Heteroaromatics (C60H24N2 and C60H30) [4], with essentially different substrates, such as Au(111), TiO2(110) and supported Graphene. These molecules are prototypical electron donors and acceptors and are in potentials of molecular electronics as promising candidates of organic conductors, and some of them interesting due to their hole injection barrier found on a variety of polycrystalline metal substrates. On the other hand, thermal-induced (cyclo)dehydrogenation leads some Heteroaromatic PAH precursors to the formation of pristine or N-doped graphene [4]. In our theoretical approach we first obtain the geometric configuration of the substrate / organic interface by using a powerful molecular dynamics DFT-based technique [1b], combined to an effective van der Waals correction in a perturbative fashion. The electronic structure and substrate / organic barrier height formation for the single molecules, as well as for the ad-layered structures, are analyzed by using the mentioned IDIS model [1b, 2], applying to the whole system a convenient energy level alignment. Within this framework we calculate the charging energy Ueff of all the isolated and ad-layered systems at the nanocontacts, determining self-consistently the transport energy gap and the organic molecule density of states. An accurate Keldish-Green-based theoretical scanning tunneling microscopy approach [2] has been performed over all the obtained structures in order to compare the results with those existing in previous literature and recent experiments by our group, finding an excellent agreement between experiments and theory [1a-e, 3a, 3b, 4].

References

1. a) J. I. Martínez et al., J. Chem. Phys. 134, 044701 (2011); b) Org. Elec. 13, 399 (2012); c) Phys. Stat. Sol. B 248, 2044 (2011); d) Chem. Phys. 390, 14 (2011); e) Phys. Rev. Lett. 108, 246102 (2012).

2. J. M. Blanco et al., Phys. Rev. B 70, 085405 (2004).

3. a) I. Fernández-Torrente et al., Phys. Rev. Lett. 99, 176103 (2007); b) Int. J. Mass Spectr. 277, 269 (2008).

4. A. L. Pinardi, J. I. Martínez, J. A. Martín-Gago et al., ACS Nano, DOI: 10.1021/nn400690e (2013).


http://www.icmm.csic.es/esisna/
Contact : Cindy ROUNTREE

 

Séminaire SPCSI - Informations pratiques

Entrée sur le site du CEA de Saclay pour les séminaires SPCSI

Afin de pouvoir entrer sur le site du CEA de Saclay veuillez adresser les données personnelles suivantes par courriel à Christine Prigian et Catherine Julien (secrétariat) un avis d’entrée vous sera alors délivré:

 

Nom:

 

 

Prénom:

Date et lieu de naissance:

Nationalité:

Nom de l'employeur:

 

Ces informations doivent être envoyées au mieux deux jours avant la date du séminaire.

Lors de votre venue vous devez vous présenter avec une carte d'identité ou un passeport en cours de validité. L'entrée sur le site se fait par l'entrée principale ou porte Nord (suivre le lien ci-dessous), un badge vous y sera remis. Demandez à l'accueil le Bât.466, ils vous renseigneront.
Les séminaires se déroulent au Bât. 466, pièce 111 (1er étage).
En cas de problème vous pouvez contacter le secrétariat au : 01 69 08 65 32 /  40 12.


Formalities for entering the CEA Saclay site for SPCSI seminars

 

 

To enter in CEA Saclay you need to send the following personal data to Christine  PRIGIAN and Catherine Julien (secretariat):

 

 

Informations utiles/Practical informations - Contact

Informations:  Access



 

Contact: Christine Prigian et Catherine Julien

 

Last Name :

First Name :

Place and date of birth :

Nationality :

Employer Name :

These informations must be preferably sent at least two days before the seminar date.

 

When you come you must have a valid ID card or passport with you.

The entrance in CEA Saclay is through the main entrance or north entrance (see link below), a pass will be delivered. Ask at the “accueil” the path for the building 466. SPCSI seminars take place in room 111 (first floor).

Any questions/troubles do not hesitate to contact our secretariat : 33 (0)1 69 08 65 32 /  40 12.

#28 - Last update : 0000-00-00 00:00:00

 

Retour en haut