Banca de DEFESA: STEFFANO FELIX DE OLIVEIRA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : STEFFANO FELIX DE OLIVEIRA SILVA
DATE: 28/03/2022
TIME: 14:00
LOCAL: Google Meet
TITLE:

Synthesis and modulation of carbon dot emission for the production of polymeric films and their use as an outer layer in light-emitting diodes

KEY WORDS:

Carbon dots, device, fluorescence and nanoparticles

PAGES: 80
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

WLED (white light emitting diode) lighting technology traditionally has utilized rare earth metals as the photoemissive layer. However, the production of WLEDs based on these elements has some advantages, such as toxicity, limited and severe preparation conditions, high cost, and non-renewable raw material source. In view of this, this work aims to synthesize carbon dots (C-Dots) by a green, fast and low-cost route to generate white light emission. C-dots from lemon bagasse (LM-Cdots and LH-Cdot) and mango leaf extracts (mg-Cdot and MS-Cdot), p-phenyldiamine (P-Cdots) and beet peel extract (bet-Cdot) were produced via microwave and hydro/solvothermal methods. Dynamic light scattering (DLS) measurements of the C-Dots exhibited a major size distribution below 10 nm. The C-Dots also showed high photostability for a time of 60 min under UV irradiation, and absorption bands characteristic of π-π* and n-π* transitions... UV-Vis absorption spectra and FTIR measurements evidenced that the C-Dots exhibited absorptions typical of the π- π* transitions of the C=C bonds (sp² domains) of the graphitic core and n- π* of the surface states, as well as surface functional groups derived from their precursors. The synthesized C-Dots exhibited maximum emission in blue, green and red, as well as excitation wavelength-dependent emission. The mg-Cdot exhibited dual emission with maxima centered in the blue and red region. The synthesized C-Dots exhibited maximum emission in blue, green and red, as well as excitation wavelength-dependent emission. The mg-Cdot exhibited dual emission with maxima centered in the blue and red region. Using chromaticity diagram (CIE) from fluorescence data, the color coordinate in modulating the prepared C-Dots was obtained, and under optimized conditions CIE corresponding to cool and warm white as well as close to pure white were observed. Finally, by a simple and sustainable route it was possible to produce a photoemissive layer based on C-dots promising for applications in WLEDs.

BANKING MEMBERS:
Presidente - 1869296 - CINTYA D'ANGELES DO ESPIRITO SANTO BARBOSA
Interna - 1318707 - ARACELIS JOSE PAMPHILE ADRIAN
Externo à Instituição - GEORGE RICARDO SANTANA ANDRADE - UFES