PH'D defense Mme Farha Cynthia

Abstract : Recently, organometallic hybrid perovskite materials are experiencing a real progress for solar cell applications. Due to particularly interesting properties: adaptable band gap, high crystallinity, high charge transport capacity and high thin film efficiency, these materials have the potential to exceed the performance limits of current technologies. They also combine a low cost and processing versatility. Among alternative device structures, carbon-based perovskite solar cells look highly promising due to their low cost and abundantly available materials (TiO2, ZrO2, carbon black and graphite powders), cost-efficient scalable fabrication methods and the inherent high stability. A one step (CH3NH3)x(AVA)1-xPbI3 perovskite solution (with AVA= ammonium valeric acid additive) was pipetted or added by the inkjet method to infiltrate mp-TiO2/mp-ZrO2 through a thick porous carbon layer. In order to reveal their maximum photovoltaic performance, these devices should be first matured under humidity and temperature. This step lasts of approximately 100-150 h and improves of the cell’s performance. In this thesis, the two infiltration methods were compared using cells before and after maturation in order to highlight the role of this step on the cells’ performance. To further investigate their stability, aging campaigns at damp heat conditions 85°C/85%RH have been conducted. Moreover, many aging campaigns were also studied with different encapsulation systems such as surlyn gasket, polyolefin, polyurethan, triple layered polyolefin and the latter with polyisobutylene. These sealants were used, enabling the humidity permeation up to solar cells and inducing probably an accelerated degradation of devices. Thanks to dedicated characterization techniques, such as J(V) measurements, the PV performance were evaluated, and such as laser beam induced current (LBIC) measurements and photoluminescence imaging, the local performances have been correlated to the degradation inhomogeneity. The modifications of the perovskite layer have been evaluated with others more common techniques (X-Ray diffraction, UV-visible absorption and photoluminescence spectroscopy).

Lionel FLANDIN : Professeur des universités Université de Savoie Mont-Blanc. Directeur de thèse
Eliane ESPUCHE : Professeure des universités. SITE Université Claude Bernard Lyon 1 - IMP/LMPB Bâtiment ISTIL. Examinateur
David RIASSETTO : Maître de conférences Grenoble-INP - PHELMA Examinateur
Thanh tuan BUI : Maître de conférences CY LPPI - Laboratoire de Physicochimie des Polymères et des Interfaces. Rapporteur
Jean-Marc CHENAL : Professeur des universités. INSA-Lyon MATEIS. Rapporteur
Sylvie NEYERTZ BROWN : Maîtresse de conférences. Université Savoie Mont Blanc. Examinateur