Revelando propriedades de células solares de perovskitas usando técnicas de radiação síncrotron

Author(s)

Rodrigo Szostak

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Química
• Defense date: 2021-07-12

Examining board members

Ana Flávia Nogueira; Lucimara Stolz Roman; André Sarto Polo; Francisco das Chagas Marques

• Advisor: Ana Flávia Nogueira; Helio Cesar Nogueira Tolentino

Abstract

The development of sustainable energy sources, specially solar energy, has become crucial for mitigating global warming. In this context, perovskite solar cells (PSCs) have received significant attention due to the high efficiency achieved in a few years and their low preparation cost. Despite these, many aspects of perovskite film formation, their structural and optoelectronic properties need to be better understood. Synchrotron-based characterization techniques are essential tools to explore the perovskite materials profoundly and have open multiple possibilities of in situ investigations. In this thesis, grazing incidence wide-angle X-ray scattering (GIWAXS) was used in situ during spin-coating preparation of perovskite films to shed light on the first steps of formation and crystallization. In situ GIWAXS allowed to follow the intermediate phases formed during the spin coating for the antisolvent method and the influence of the relative humidity, composition, and solvent proportions. The same strategy was used to study the solvent quenching method, which replaces the antisolvent with an inert gas flow. The influence of the solvent (dimethyl sulfoxide, DMSO vs. n-methylpyrrolidone, NMP) and composition were investigated, revealing completely different intermediate phases, depending on the solvents and on the perovskite composition. A higher amount of Cs and NMP inhibit the formation of hexagonal phases leading to better performance for formamidinium-based perovskite. To a further a deeper characterization at the nanoscale, the nano-FTIR technique was employed, unravelling the nanochemistry heterogeneities of these perovskite films. The results revealed PbI2 and hexagonal phase grains within the compound, depending on the composition (with and without Cs) (AU)

• FAPESP's process: 17/12582-5 - Perovskites with mixed cations: Relationship between structure, composition, electronic properties and efficiency of solar cells
• Grantee: Rodrigo Szostak
• Support Opportunities: Scholarships in Brazil - Doctorate