Structural and Processing Modification of Perovskite for the Optimization of Photovoltaic Devices
- Autores: Patricio Serafini
- Directores de la Tesis: Iván Mora-Seró (dir. tes.), Eva María Barea Berzosa (dir. tes.)
- Lectura: En la Universitat Jaume I ( España ) en 2023
- Idioma: inglés
- Número de páginas: 234
- Tribunal Calificador de la Tesis: Silvia Colella (presid.), Francisco Fabregat Santiago (secret.), Michele Sessolo (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Energy consumption has experienced an exponential increase, mostly in the last century. To achieve this demand, the use of fossil fuels at low cost with high energy production has been used. However, the consequence of their use is the production of greenhouse gases, such as carbon dioxide (CO2) emissions.[1-3] As observed in previous eras of Earth, an increase in CO2 feeds the increase of temperature leading to a feedback relation between both variables. In this way, it is anticipated that global warming causes catastrophes for both the environment and humans.[4,5] The use of clean and renewable energy emerges as a solution to cut this feedback loop, as during their operative life they do not produce CO2 employing almost unlimited sources to power them. Among the different clean energies, solar energy appears to be the one that could rapidly decrease the energy consumption of fossil fuels, with the added advantage of reducing residential energy consumption and making consumers self-sustainable.
Since the beginning, silicon (Si) solar cells have been the most utilized devices.[6] However, historically the cost of production was higher which makes them less desirable in comparison with other energy sources. So, the goal of reducing the cost of production to make solar cells available for most people led to search new active materials.
This opened the door to the 2nd generation thin-film solar cells with the most significant examples being cadmium telluride (CdTe) and copper indium gallium di-selenide (CIGS), which were less expensive but had lower efficiency and containing toxic or low abundant elements.[7-9] Consequently, the research moved towards the 3rd generation materials to solve the issues of the preceding generation with lower production cost and high efficiency, but in many cases with the disadvantages of presenting lower stability.[10-13] Recently, among the 3rd generation materials, halide perovskite semiconductors have shown performances close to Si solar cell, with low exciton binding energy, direct bandgap, high mobility, among other characteristics. However, poor stability in halide perovskites remains an issue to be overcome.
To solve the different problems of perovskite solar cell is necessary to understand the material behavior and its degradation mechanism. In this work I explore different routes to enhance the lifetime of devices by employing passivation, change the chemical composition or modify the processing methodologies.
The first publication depicts the introduction of phenylethyl ammonium iodide (PEAI) in the antisolvent step, which passivates the defects on the different MAPbI3, MA0.9Cs0.1PbI3 and MA0.5FA0.5PbI3 perovskites. Consequently, the passivation leads to a decrease in the crystal domain size improving films stability up to 1200 h by following absorbance and solar cells device performances.
In the second paper, structural modification was performed by changing the chemical composition of perovskite using a mixed cation of methylammonium and guanidinium (GU). Due to the bigger size of GU, low quantities of it were used in the perovskite to have a 2D/3D perovskite. Such quantities cause the tilting of the metal-halide octahedral, modifying the carrier transport obtaining a better efficiency and stability using 7% mol of GU. In addition, PbS quantum dots (QDs) were introduced to each GU quantity in order to extend lifetime of devices. The introduction of PbS QDs were observed to cause the modification in the microstrain in perovskite films causing the reduction of performance in one side but lifetime was improved in devices with higher amounts of GU.
The third paper presented in this thesis explore a non-invasive mechanism to understand and develop a more stable perovskite. To achieve this, methylammonium lead iodide (MAPbI3) perovskite was synthesized following a technique that contributes with lower amount of solvents and faster processing of crystal growth mechanism. Flash infrared annealing (FIRA) allows us to perform precise modification of annealing time which enables defect-reduction in perovskite semiconductors which extends the operational and ambient stability.
