Banca de DEFESA: GABRIELA NASCIMENTO PEREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : GABRIELA NASCIMENTO PEREIRA
DATA : 25/02/2019
HORA: 14:00
LOCAL: Instituto de Química
TÍTULO:

THEORETICAL STUDY OF ADSORPTION OF THIOPHENE DERIVATIVE DIMERS ON GRAPHENE

PALAVRAS-CHAVES:

Semiconductors, graphene, P3HT, DFT, thiophene.

PÁGINAS: 81
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Química do Estado Condensado
RESUMO:

Semiconductors play an important role from the technological point of view, being employed
in several electronic devices, such as televisions, computers, cell phones, solar panels, among
others. These semiconductors, consist mostly of inorganic materials, such as silicon and
germanium. However, recently, organic semiconductors have earned attention in this scenario,
allowing the creation of cheaper and more flexible technologies, having application, for
example, in televisions and cell phones already available in the commercial market. Thus, in
search of development of new technologies, semiconductors has been the target of several
studies, which investigate potential systems that allow the construction of smaller and better
performing devices, linked to cost x benefit. Graphene and an organic polymer known as poly
(3-hexylthiophene) (P3HT) are considered as promising systems for technological use, giving
shape to the hybrid semiconductors. Since thiophene is the base that constitutes P3HT, the
adsorptions and properties of the polymer come mainly from the heterocyclic ring of thiophene,
as reported in the literature. Thus, one way to investigate this type of system can be obtained
by thiophene dimers, used to mimic the behavior of P3HT. In this context, this work aims to
evaluate the characteristics of the adsorption process between the graphene / thiophene dimer
system, studying the influence of donors and withdrawing groups on the organic matter, as well
as the position of the molecule on the graphene surface. The calculations are performed using
a theoretical approach using the Density Functional Theory (DFT) method in geometry
modeling. The structural characteristics of the systems were observed through the evaluation
of geometric properties, such as the verification of the C-C and C-S bond distances of the
thiophene rings and the distances between the surface and the adsorbed molecule. The
adsorption energy values obtained were low, which shows a quite physical adsorption process.
As techniques of adsorption analysis and investigation of the electronic structure were used:
differential charge density (DDC), density of states (DOS) and Band Structure. Thus, the
different behaviors of the systems in relation to the type of group used can be observed. From
the results obtained in these analyzes, it can be verified that the systems involved present a
weak interaction, basically physical, being governed by Van der Waals interactions.
Furthermore, no significant charge transfer between the two structures was observed, in contrast
to what was expected. This characteristic was maintained despite the addition of dopant groups
to the system. The present work can still be expanded to investigate properties that have not
been explored here, and serve as a basis for further studies.

MEMBROS DA BANCA:
Presidente - 1115883 - ANTONIO MARQUES DA SILVA JUNIOR
Externo ao Programa - 1808284 - MARCIO SOARES PEREIRA
Externo à Instituição - HÉLIO FERREIRA DOS SANTOS - UFJF