Banca de DEFESA: CASSIO LONGATI NUNES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : CASSIO LONGATI NUNES
DATE: 17/02/2022
TIME: 14:00
LOCAL: UFSJ
TITLE:

Impedance Spectroscopy Analysis of Quantum Dots Sensitized Solar Cells

KEY WORDS:

Impedance Spectroscopy. Quantum Dots. Solar cell.

PAGES: 75
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física da Matéria Condensada
SPECIALTY: Transp. Eletrônicos e Prop. Elétricas de Superfícies; Interfaces e Películas
SUMMARY:

The increase in energy demand, environmental problems and the possible scarcity of non-renewable energy sources are some of humanity's recent concerns. In this context, scientists are looking for ways to develop technologies for energy production from renewable sources and with low environmental impact. Quantum dot sensitized solar cell (QDSSC) is a promising technology that has low production cost, easy manufacturing process and high theoretical efficiency (~44%). However, the current efficiency of these QDSSCs is around 14%. Recently, researchers have been optimizing each component of the QDSSC to reduce energy losses. And to understand these losses, the method of characterization by Impedance Spectroscopy allows studying the physical and chemical processes that occur at the cell interfaces, such charge recombination and charge transfer, trap states, degradation processes and thus improve the efficiencies of these solar cells. In this work, QDSSCs were constructed using TiO2 as photoanode and copper, indium and sulfur (CIS) quantum dots as sensitizers in the photoanode. The counter electrodes, based on CuS, were prepared under different conditions of concentrations and temperatures, seeking to understand the variation of charge transfer resistances of the counter electrodes as a function of the morphology of the deposited films. Using techniques of morphological characterization and electrical characterization, it was possible to optimize the deposition conditions of the counter electrode, thus obtaining a counter electrode with low charge transfer resistance and good catalytic activity, for the regeneration of the polysulfide electrolyte. It was determined that the deposition condition at 80°C and reagent concentration of 0.2 M was the one that presented the best results. Finally, the QDSSC was built, using the prepared counter electrodes and it was found that the use of optimized counter electrodes led to greater efficiency. From the electrical characterization with the Impedance Spectroscopy technique, it was possible to relate the low recombination resistance of the charge carriers, with a low filling factor. With an optimization of the processes in the preparation of the device, an improvement in the filling factor and an increase in the recombination resistances of the charge carriers were obtained.Thus, the factors that influenced the photovoltaic performance were discussed based on the parameters obtained from the Impedance Spectra, proving the effectiveness of the Impedance Spectroscopy technique in the study and understanding of these parameters, which are fundamental for the constant evolution of these photovoltaic devices.

BANKING MEMBERS:
Presidente - 1527524 - WAGNER SOUZA MACHADO
Interno - 1217987 - ANDRE LUIZ MOTA
Externo à Instituição - JOSÉ PEDRO MANSUETO SERBENA - UFPR