Banca de QUALIFICAÇÃO: STEFFANO FELIX DE OLIVEIRA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : STEFFANO FELIX DE OLIVEIRA SILVA
DATE: 30/09/2021
TIME: 14:00
LOCAL: Google Meet
TITLE:

Carbon dots in white light emitting diodes (WLEDs): From synthesis to design of sustainable lighting devices

KEY WORDS:

Carbon dots, device, fluorescence and nanoparticles

PAGES: 30
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

WLED (white light emitting diode) lighting technology traditionally makes use of rare earth metals as photoemissive layer. However,
the production of WLEDs based on these elements has some disadvantages, such as toxicity, limited and severe preparation
conditions, high cost and non-renewable raw material source. So, this work aims to synthesize carbon dots (C-Dots) by a green, fast
and low-cost route to generate white light emission. C-Dots were produced via microwave (5 min) and hydrothermal (180 °C for 4
hours) methods from lemon bagasse extract (L-CDots) and p-phenyldiamine (p-CDots), respectively. Dynamic light scattering (DLS)
measurements of the L-Cdots and p-CDots exhibited an average size of 5.60 and 6.08 nm, respectively. The C-Dots showed high
photostability for a time of 60 min under UV irradiation, and absorption bands characteristic of π-π* and n-π* transitions. L-CDots
showed excitation wavelength-dependent emission (ʎexc), with maximum emission at 490 nm (ʎexc= 410 nm). On the other hand, pCDots showed independent emission for ʎexc greater than 410 nm, with maximum emission at 610 nm (ʎexc= 470 nm). The modulation
of these C-Dots in appropriate proportions allowed obtaining cold and warm white light emission with chromaticity diagram (CIE) x
and y coordinates and correlated color temperatures (CCT) of (0.30;0.33 and 0.34;0.35) and (7222 and 5024 K), respectively. Finally,
by a simple and sustainable route a photoemissive layer based on C-Dots promising for applications in WLEDs was produced.

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