Banca de QUALIFICAÇÃO: LUIZ FELIPE DA HORA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUIZ FELIPE DA HORA
DATE: 30/06/2026
TIME: 10:00
LOCAL: Auditório Labtam
TITLE:

A New Approach for Encapsulating and Stabilizing Perovskites Using Different (Co)polymers

KEY WORDS:

Perovskite solar cells; Polymer encapsulation; Copolymers synthesis; Perovskite stability; Lead-free perovskites; Passivatio

PAGES: 93
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Compostos Organo-Metálicos
SUMMARY:

 Perovskite solar cell have is one of the most promising photovoltaic technologies due to their excellent optoeletronic properties and low fabrication cost. However, their practical application is still limited by poor environmental stability, mainly caused by moisture, oxygen, UV radiation, and thermal stress. Therefore, the development of effective encapsulation and passivation strategies is essential for improving the durability of perovskite-based devices. In this work, two different polymeric materials were investigated as protective layers for perovskite films under ambient conditions with relative humidity above 70%.

Initially, a poly(methyl methacrylate-butyl acrylate-methacrylic acid) [P(MMA-BA-MAA)] copolymer was synthesized by free-radical solution polymerization. The use of semicontinuous initiator addition and a higher butyl acrylate content resulted in a conversion of approximately 99%. FTIR, DSC, and UV-Vis analyses confirmed the successful synthesis of the copolymer and demonstrated characteristics suitable for encapsulation applications, including transparency in the visible region, UV absorption, electrical insulation, hydrophobicity, and a glass transition temperature of 43 °C. The copolymer was then applied as an encapsulant for lead-free Cs₃Bi₂I₉ perovskite films synthesized under ambient conditions without a controlled atmosphere. Stability tests showed that the encapsulated samples maintained their optical and morphological characteristics during a 75-day aging period under sunlight exposure and high humidity, while non-encapsulated samples exhibited severe degradation.

In a second stage, poly(methyl methacrylate) (PMMA) films with concentrations ranging from 4 to 150 mg/mL were evaluated as encapsulation and passivation layers for CsPb₀.₇₅Sb₀.₂₅I₃ perovskite films. Hydrophobicity and water absorption analyses demonstrated that increasing PMMA concentration improved the protective properties of the polymeric films, with the 150 mg/mL formulation showing the best overall performance. Encapsulation tests under ambient conditions and direct water exposure confirmed the ability of PMMA to reduce moisture penetration and delay perovskite degradation. Furthermore, SEM and SEM-EDS analyses revealed that PMMA not only improved environmental stability but also influenced crystallization and film morphology, promoting denser, more homogeneous, and better-connected crystal structures.

Overall, the results demonstrate that both the synthesized P(MMA-BA-MAA) copolymer and commercial PMMA are effective materials for improving the stability of perovskite films under high-humidity conditions. In addition to providing efficient protection against environmental degradation, the synthesized copolymer showed a lower cost than commercial PMMA, demonstrating its potential as a low-cost and competitive alternative for future perovskite-based photovoltaic applications.

COMMITTEE MEMBERS:
Externo à Instituição - ANGELO ANDERSON SILVA DE OLIVEIRA - UFRN
Interna - 349770 - DULCE MARIA DE ARAUJO MELO
Interno - 1198847 - JOSE LUIS CARDOZO FONSECA
Externo à Instituição - RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS - UFRN