EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:

What Hampers Electron Transport in Organic Crystals? A Close Look at Band-like Transport in N-type Organic Semiconductors

Prof. Dr. Emanuele Orgiu

Institut National de la Recherche Scientifique – INRS, Québec – Canada

Resumen:

Charge transport in organic semiconductors is notoriously sensitive to the presence of disorder, both intrinsic and extrinsic, especially for n-type materials. Intrinsic dynamic disorder stems from large thermal fluctuations both in intermolecular transfer integrals and (molecular) site energies in weakly interacting van der Waals solids and sources transient localization of the charge carriers. The molecular vibrations that drive transient localization typically operate at low-frequency (< a-few-hundred cm-1), which makes it difficult to assess them experimentally. Hitherto, this has prevented the identification of clear molecular design rules to control and reduce dynamic disorder. In addition, the disorder can also be extrinsic, being controlled by the chemical and physical «coupling» of the π-conjugated core to the gate dielectric. During the Colloquium, I will present a comprehensive study of charge transport in two closely related n-type molecular organic semiconductors using a combination of temperature-dependent inelastic neutron scattering and photoelectron spectroscopy corroborated by electrical measurements, theory and simulations. By doing so, unambiguous evidence is provided that ad hoc molecular design enables to free the electron charge carriers from both intrinsic and extrinsic disorder to ultimately reach band-like electron transport.

Fecha: 12 de noviembre de 2021 – (viernes) – Horário: 10:15 a.m.

Enlace acceso al canal de youtube: https://youtu.be/TE3LD1NKi4c

EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:

Gauge invariant quantum thermodynamics: consequences for the first law

Prof. Dr. Lucas Chibebe Céleri

Instituto de Física – UFG

Resumen:

Universality of classical thermodynamics rests on the central limit theorem, due to which measurements of thermal fluctuations are unable to reveal detailed information regarding the microscopic structure of a macroscopic body. When small systems are considered and fluctuations become important, thermodynamic quantities can be understood in the context of classical stochastic mechanics. A fundamental assumption behind thermodynamics is therefore that of coarse-graining, which stems from a substantial lack of control over all degrees of freedom. However, when quantum systems are concerned, one claims a high level of control. As a consequence, information theory plays a major role in the identification of thermodynamic functions. Here, drawing from the concept of gauge symmetry, essential in all modern physical theories, a new, intermediate, route is put forward. Working within the realm of quantum thermodynamics, a physically motivated gauge transformation, which encodes a gentle variant of coarse-graining behind thermodynamics, is explicitly constructed . As a consequence, quantum work and heat are reinterpreted, as well as the role of quantum coherence.

Fecha: 5 de noviembre de 2021 – (viernes) – Horário: 10:15 a.m.

Enlace acceso al canal de youtube: https://youtu.be/ieeh_LtXBgI

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O Programa de Pós-Graduação em Física da UFSC torna público os editais do processo seletivo para os cursos de mestrado e doutorado para ingresso no semestre 2022/1.

As inscrições ocorrerão no período de 1 a 30 de novembro de 2021. O PPGFSC utiliza a nota do Exame Unificado de Pós-Graduações em Física – EUF para ingresso nos cursos de mestrado de doutorado.

Click aqui e acesse o site do processo seletivo do PPGFSC/UFSC.