Banca de QUALIFICAÇÃO: Fernando Teixeira Bueno

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Fernando Teixeira Bueno
DATE: 22/12/2023
TIME: 14:30
LOCAL: Auditório do IF
TITLE:

Understanding triplet-to-singlet energy transfer pathways in organic systems

KEY WORDS:

Singlet excitons; energy transfer; triplet excitons; FRET

PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

The phenomenon of afterglow, characterized by the emission of light persisting long after the cessation of external excitation, has intrigued researchers since the 18th century. From early theoretical explanations rooted in caloric theory to the distinct categorization of phosphorescence by Sir George Stokes, the field has evolved significantly. This work delves into the theoretical characterization of the photophysics of NPB (N,N-di(naphtha-1-yl)-N,N-diphenylbenzidine) and DCJTB (4-(dicyano-methylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran) molecules, considering vibrational and medium effects. The study simulates absorption and emission spectra, estimates rates of fluorescence, phosphorescence, and reverse intersystem crossing (rISC), and computes Förster radii for singlet-to-singlet and triplet-to-singlet (TTS) transfers. Experimental evidence of afterglow via TTS transfers between NPB and DCJTB prompted a full theoretical investigation. The findings reveal that while NPB exhibits low rISC rates, TTS transfers emerge as an alternative triplet harvesting mechanism, outperforming both phosphorescence and nonradiative decay. Kinetic Monte Carlo simulations in a host-guest system further substantiate TTS-derived afterglow, demonstrated by a fluorescence timescale of hundreds of milliseconds. Noteworthy is the emphasis on morphological considerations, where increasing acceptor concentration enhances TTS efficiency, highlighting the pivotal role of intermolecular interactions. These results contribute to understanding the working of the TTS mechanism, opening avenues for the design of new persistent luminescent materials. This study holds implications for diverse technological applications, offering a sustainable and efficient approach to luminescent device development.

COMMITTEE MEMBERS:
Interno - 1122772 - GERALDO MAGELA E SILVA
Externo ao Programa - 1211646 - MARCO CEZAR BARBOSA FERNANDES - nullPresidente - 1273560 - RICARDO GARGANO
Interno - 1702412 - WILIAM FERREIRA DA CUNHA