Formulação de um modelo de transições eletrônicas e estudo da agregação em oligômeros conjugados a base de tiofeno-benzeno-tiofeno

Abstract

Organic semiconducting and luminescent materials have a fundamental role in technological advances in the fields of electronics, optics, and communications. Therefore, understanding the optical properties of these materials is essential for the development of efficient devices. In this work, the photophysical properties of thiophene–benzene–thiophene (TBT) oligomers were investigated, aiming to understand the type of aggregate formed in these systems. Optical absorption and photoluminescence (PL) experiments were carried out to elucidate the emission mechanisms as a function of concentration and excitation power. Fluorescence lifetime measurements were also performed to determine how long the generated exciton remains in the excited state before recombining. The system’s reversibility after irradiation was analyzed to assess whether the observed aggregates were reversible or permanent. Finally, a computational analysis of the photoluminescence spectra was conducted to extract parameters related to the electronic transition energy and the electron vibrational mode coupling, using a two emissive species model. At the end of the study, a model for the electronic transitions of the analyzed oligomers was proposed, along with the identification of the aggregate type, characterized as an exciplex.