Banca de DEFESA: THAIS ADRIANY DE SOUZA CARVALHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : THAIS ADRIANY DE SOUZA CARVALHO
DATE: 04/02/2022
TIME: 14:00
LOCAL: On-line
TITLE:

SYNTHESIS AND CHARACTERIZAITON OF HALYDE METALIIC LEAD-FREE PEROVSKITE NANOCRYSTALS. 

KEY WORDS:

Perovskites, Lead-free, Nanomaterials, Toxicity.

PAGES: 77
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

In recent years, perovskites of formula CsPbX₃ (X= Cl, Br or I) have shown potential in various applications such as photodetectors, solar cells, light emitting diodes (LEDs), nuclear radiation detectors, optical fibers, lasers and photocatalysts. This is mainly stimulated by its excellent properties such as easy processability, high photoluminescence quantum yield, narrow emission bands and adjustable bandgap due to the change in composition, which can cover the entire visible spectrum. It is noteworthy that both the issues related to toxicity, stability and the possibilities of large-scale use are still obstacles to obtaining practical applicability of technologies that use these materials. Lead-free perovskites, the term given to lead-free perovskites, have been considered of great scientific interest due to their less toxic nature, improved stability, simple processing method and possibility of carrying out synthesis at low temperature. More ecologically correct methods for obtaining them, as well as the development of less toxic materials are still in the initial stages. In this work, a synthesis and characterization of perovskite nanocrystals was carried out, with a substitution of lead for bismuth or copper, through different methods, hot injection or using room temperature. The materials were characterized using UV-Vis absorption spectroscopy, photoluminescence spectroscopy, radiative decay lifetime curves, photoluminescence quantum yield determination and X-ray diffraction. Cs₃Bi₂Br₉ and Cs₃Cu₂Cl₅ showed high crystallinity and optical properties such as absorption and emission bands characteristic to their phases. The synthesis of copper and cesium halide nanocrystals was optimized, and the method using higher temperatures proved to be effective in increasing the emission intensity of the nanomaterial, without interfering with other properties. In addition, a large Stokes shift and a long decay time were found for Cs₃Cu₂Cl₅ nanocrystals, thus demonstrating great potential for future applications in lighting devices, replacing lead perovskites.

BANKING MEMBERS:
Presidente - 1443844 - MARCO ANTONIO SCHIAVON
Interno - 1527524 - WAGNER SOUZA MACHADO
Externo à Instituição - JOSE ANTONIO SOUZA - UFABC