Banca de QUALIFICAÇÃO: ELIANE APARECIDA MORAIS
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.STUDENT : ELIANE APARECIDA MORAIS
DATE: 15/12/2022
TIME: 14:00
LOCAL: Santo André
TITLE:
Anion-exchange and reducing dimensionality strategies in halide perovskites towards UV emission
PAGES: 70
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física da Matéria Condensada
SPECIALTY: Prop. Óticas e Espectrosc. da Mat. Condens; Outras Inter. da Mat. com Rad. e Part.
SUMMARY:
Metal halide perovskites are promising candidates for application in photovoltaic devices and in light emitting diodes (LEDs). They have excellent optoelectronic properties including high photoluminescence quantum yield (PLQY) and tunable direct bandgaps. The fabrication of light emitting device by using this perovskite family with high efficiency can be used in interdisciplinary fields. For instance, UV light has been used to inactivate germs such as bacteria and viruses and has a significant effect on disinfecting surfaces. The biggest challenge, nowadays, is to synthesize these materials with emission in the UV region through size effect or changing dimensionality. In this work, all- inorganic CsPbX3 halide perovskites in the form of quantum dots (QDs) with X = I, Br, Cl were studied. Structural and morphological characterizations indicated that all the QDs samples were successfully synthesized through chemical routes. As Cl ions are introduced into the perovskite structure, the unit cell volume and lattice parameters decreased and a blue shift is observed in the photoluminescence spectrum. Further addition of F ions, which have higher electronegativity and smaller ionic radius, leads to an improvement in PLQY from 9.4% to 11.2%, but UV shift is not observed. The 2D (M)2MAn-1PbnX3n+1, halide perovskites, with X = I, Br, Cl, MA = methylammonium and M = n-butylammoniumwere successfully synthesized and studied. The organic molecules (M) act as a spacer between n [PbX6]4- octahedral layers. We observe that the inorganic layers show strong quantum confinement effect enlarging the band gap energy and shifting PL emission peak to UV region. Within this context, we present a systematic study involving synthesis and physical properties of these 2D materials. By using anion exchange strategy from I to Br and to Cl in (BA)2PbX4, we observe a UV shift, where the perovskite (BA)2PbCl4 showed an emission in 357 nm.
BANKING MEMBERS:
Presidente - Interno ao Programa - 1305186 - SERGIO BROCHSZTAIN
Membro Titular - Examinador(a) Interno ao Programa - 1671688 - ANDRE SARTO POLO
Membro Titular - Examinador(a) Interno ao Programa - 1600858 - HERCULANO DA SILVA MARTINHO
Membro Titular - Examinador(a) Externo ao Programa - 1968862 - JOSE JAVIER SAEZ ACUNA
Membro Suplente - Examinador(a) Interno ao Programa - 1544408 - GUSTAVO MARTINI DALPIAN
Membro Suplente - Examinador(a) Interno ao Programa - 1761120 - DANILO JUSTINO CARASTAN
Membro Suplente - Examinador(a) Externo ao Programa - 1762413 - LUCIANO SOARES DA CRUZ
Membro Suplente - Examinador(a) Externo ao Programa - 3066318 - JULIAN ANDRES MUNEVAR CAGIGAS