Banca de QUALIFICAÇÃO: MARIA ZILDA OLIVEIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARIA ZILDA OLIVEIRA
DATE: 18/10/2024
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

Nanostructured materials using perovskites for applications in renewable energy sources

KEY WORDS:

Perovskite, solar cells, paste, toxicity reduction.

PAGES: 75
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

Perovskite-structured materials have gained prominence in the field of optoelectronic devices, showing significant advancements in recent decades. Metal halide perovskites have been developed as energy converters with unprecedented speed, achieving conversion efficiencies (in the lab) comparable to those of silicon-based photovoltaic technology, which is already widely commercialized. However, this technology faces challenges, such as the use of lead-based (Pb) materials, whose toxicity is a major concern. Considerable efforts have been made to replace Pb with alternative cations, although these alternatives have yet to match the efficiency or stability of Pb-based compounds. Another significant challenge is scalability, as it is difficult to maintain the properties and uniformity of perovskite films over large areas. In the present study, perovskite films were obtained by depositing a precursor paste, resulting in solar cells with conversion efficiencies comparable to those achieved using the dip coating method. Devices using the CsPbBr3 composition reached an efficiency of 3%, with short-circuit currents of 6 mA/cm² and relatively low fill factors (FF) around 47%, likely due to the absence of hole transport layers (HTL). A modification in the method, partially substituting the Pb precursor with Zn, led to devices with reduced lead content and increased current density, despite a reduction in FF. The condition with 50% Pb substitution was the most promising, with current densities up to 9.8 mA/cm² and efficiency of 4%. Substitutions higher than 50% significantly impaired charge extraction in the devices. Despite the reduction in FF, the devices showed a substantial increase in current density and the important benefit of reduced lead usage. The assembly of devices without HTL may have contributed to the lower FF, suggesting that the inclusion of an HTL could improve charge transport and, consequently, FF. The study is ongoing with additional characterizations, film thickness optimizations, and evaluation of alternative compositions. The results so far indicate that these materials and devices are promising, not only due to the ease of deposition and scalability but also for their reduced toxicity, making them highly interesting systems for future applications.

COMMITTEE MEMBERS:
Externo à Instituição - WAGNER SOUZA MACHADO - UFSJ
Externa à Instituição - LARISSA AGOSTINHO DE SANTA CRUZ OLIVEIRA
Presidente - 3100969 - NATHALIA BEZERRA DE LIMA