Banca de QUALIFICAÇÃO: ALESSANDRA RESENDE GOMES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALESSANDRA RESENDE GOMES
DATE: 28/02/2023
TIME: 09:00
LOCAL: remoto
TITLE:

CHARACTERIZATION AND OPTIMIZATION OF V2O5 FILMS FOR FLEXIBLE SOLAR CELLS

KEY WORDS:

SOLAR CELLS, NATURALS DYES, DSSC.

PAGES: 1
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SUMMARY:

Due to the growing global demand for energy, renewable energy becomes of great interest. In addition to being an inexhaustible source of energy, renewable energy uses non-polluting materials. Research related to the use of solar energy has intensified in recent years and a breakthrough in photovoltaic energy is only possible with low production costs. Characterization and optimization studies of solar cells help in the development of more efficient and low-cost cells. This work aims to characterize flexible solar cells using natural dyes without purification process. The characterization was also carried out on the components of the DSSC (Dye Solar Sensitized Cels). Before the assembly of the DSSCs, a study of the energies of the components of the solar cell was carried out in order to verify the feasibility of assembling each of the cells analyzed For the assembly of the DSSC photoanode, the following semiconductors were used: V2O5 and VO2 and the dyes: strawberry, blackberry, blueberry and jabuticaba wine extracts deposited on the surface of the PET-ITO. The counter electrode (cathode) was produced using PANI electrodeposited on the surface of the PET-ITO and the electrolyte used was the iodide/triiodide pair. Several conditions of PANI electrodeposition were evaluated, with condition 1 being selected for the assembly of the DSSC because it presents some favorable conditions, such as: macrovisual uniformity of the film, values of the appropriate HOMO, LUMO and bandgap orbitals. Through the UV-VIS spectrophotometry technique it was possible to determine characteristic absorption bands of the PANI in its conductive form (emeraldine salt), demonstrating that the PANI could be used as a counter electrode of the DSSC, replacing platinum, thus reducing the cost of the DSSC. extracts for mounting the DSSC: strawberry, blackberry and blueberry. Jabuticaba wine was not selected because it is not energetically favorable for DSSC with the other components used in this work. Solar cells without the presence of dye were also mounted for comparison with DSSCs. As a result, DSSCs using V2O5 as a semiconductor were those with the highest efficiency. This fact may be related to the greater crystallinity of the film in relation to VO2, demonstrated in X-ray diffraction analysis. Comparing the efficiency of solar cells without dye and solar cells using dye, it was possible to state that the dyes were able to sensitize the DSSCs, with the exception of the CS3 solar cell. Thus, in addition to the blueberry not being able to sensitize the DSSC, it still served as a physical barrier to electrons, as can be seen by the fact that the efficiency of the CS3 solar cell was lower than the respective solar cell without dye (CS1). Flexible solar cells using natural dyes have low efficiencies (less than 1%) compared to flexible cells, however, their cost tends to be very low. Changes to DSSCs components, in addition to the study of new materials and compositions, can increase the efficiency of flexible solar cells, such as: replacing the liquid electrolyte, semiconductor doping, post-treatment in the photoyear, among others.

BANKING MEMBERS:
Externo à Instituição - ROGERIO DE OLIVEIRA
Externo à Instituição - MARCELO MULATO - USP
Externo à Instituição - RODRIGO FERNANDO BIANCHI - UFOP