{"668042":{"#nid":"668042","#data":{"type":"event","title":"PhD Defense by Juanita Hidalgo","body":[{"value":"\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003ETHE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING\u003C\/span\u003E\u003C\/strong\u003E\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u0026nbsp;\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EGEORGIA INSTITUTE OF TECHNOLOGY\u003C\/span\u003E\u003C\/strong\u003E\u0026nbsp;\u0026nbsp;\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EUnder the provisions of the regulations for the degree\u003Cbr \/\u003E\r\n\u0026nbsp;\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EDOCTOR OF PHILOSOPHY\u003C\/span\u003E\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003Eon Monday, June 26, 2023\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003E2:30 PM EST\u003C\/span\u003E\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cspan\u003E\u003Cstrong\u003Ein person in Kendeda 210\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003Eor via Zoom \u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Ca href=\u0022https:\/\/gatech.zoom.us\/j\/4654817205?pwd=a3FsVnBQckVRaEIrNWVpZWxrMmJxQT09\u0022 target=\u0022_blank\u0022\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cspan\u003Ehttps:\/\/gatech.zoom.us\/j\/4654817205?pwd=a3FsVnBQckVRaEIrNWVpZWxrMmJxQT09\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/a\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EMeeting ID: 465 481 7205\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EPasscode: 093557\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003Ewill be held the\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EDISSERTATION DEFENSE\u003C\/span\u003E\u003C\/strong\u003E\u003Cbr \/\u003E\r\n\u003Cbr \/\u003E\r\n\u003Cspan\u003E\u003Cstrong\u003Efor\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EJuanita Hidalgo\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003E\u0022Structure-Property Relationships in Lead Halide Perovskites for Solar Cells\u0022\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003ECommittee Members:\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u0026nbsp;\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EProf. Juan-Pablo Correa-Baena, Advisor, MSE\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EProf. Hamid Garmestani, MSE\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EProf. Faisal Alamgir, MSE\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EProf. Nazanin Bassiri-Gharb, ME\/MSE\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EProf. Angus Wilkinson, CHEM\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u0026nbsp;\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003EAbstract:\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003ELead halide perovskites (LHPs) solar cells, particularly FA-based, have made impressive advancements in solar energy conversion, achieving high power conversion efficiencies exceeding 26% for a single junction device. However, the limited long-term stability of these devices has hindered their commercialization. The instability issues are influenced by both internal and external factors, leading to rapid degradation of the perovskite phase and overall device performance. Various strategies have been used to stabilize the perovskite phase, but it is crucial to investigate the underlying mechanisms that govern the structural characteristics of the polycrystalline thin films. This dissertation tackles the challenges associated with the instability of LHPs by investigating the complex relationship between structure, properties, and performance in perovskite solar cells. Advanced X-ray characterization techniques are employed to examine the structural properties of FA-based compositions. Understanding the mechanisms and establishing correlations between structure and properties is possible to lay the foundation of a more robust, stable, and efficient material. This dissertation presents a first step toward the design and optimization of LHPs.\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003EThe first part of this dissertation explores the crystallographic orientation in lead bromide perovskites, demonstrating that the solvent and organic cation used in the precursor solution significantly affect the preferred orientation of the deposited perovskite thin films. The solvent affects the early stages of crystallization and induces preferred orientation by preventing colloidal particle interactions. The choice of organic cation influences the degree of crystallographic orientation, with methylammonium-based perovskites showing a higher degree of orientation than formamidinium-based ones due to a lower surface energy of a specific facet. These findings identify the importance of understanding (1) the precursor solution chemistry, (2) the facet properties and its correlation with the structural properties of the polycrystalline LHP film, and (3) the effect of crystallographic orientation on charge carrier transport in perovskite solar cells. \u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003EThe second part of this dissertation studies the mechanisms causing FA-based lead iodide perovskites to degrade under water and oxygen exposure. Contrary to common knowledge on humidity-induced degradation, the synergistic role of water and oxygen in accelerating phase instability of LHPs is revealed. The study uncovers a surface reaction pathway involving the dissolution of formamidinium iodide (FAI) by water followed by the oxidation of iodide, playing a crucial role in causing the subsequent and irreversible undesired phase transformations from perovskite into non-perovskite phases. The interplay of \u003Cem\u003Ein-situ \u003C\/em\u003Eexperimental techniques with theoretical calculations provides a detailed understanding of the degradation mechanisms, leaving the foundation to design strategies to design more durable and efficient materials. This dissertation delves into strategies for stabilizing the perovskite phase. A hydrophobic molecule, phenethylammonium iodide (PEAI), is used to stabilize FA-based perovskites. Adding PEAI hinders undesired phase transformations and leads to a more stable material with improved solar cell power conversion efficiency and enhanced charge carrier mobilities and lifetimes. Further, adding Br to mixed cation lead iodide perovskites improves their phase stability at low temperatures.\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003EOverall, understanding structure-property-performance relationships in lead halide perovskites is necessary for resolving the main challenge of instability in perovskite solar cells. This dissertation lays the groundwork for future research efforts to investigate the fundamentals of LHPs and broaden their applications in solar cells and beyond.\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n","summary":"","format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003E\u003Cspan\u003E\u003Cspan\u003E\u003Cstrong\u003E\u003Cspan\u003E\u0022Structure-Property Relationships in Lead Halide Perovskites for Solar Cells\u0022\u003C\/span\u003E\u003C\/strong\u003E\u003C\/span\u003E\u003C\/span\u003E\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":"\u0022Structure-Property Relationships in Lead Halide Perovskites for Solar Cells\u0022"}],"uid":"27707","created_gmt":"2023-06-09 15:07:37","changed_gmt":"2023-06-09 15:07:37","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2023-06-26T14:30:56-04:00","event_time_end":"2023-06-26T16:30:00-04:00","event_time_end_last":"2023-06-26T16:30:00-04:00","gmt_time_start":"2023-06-26 18:30:56","gmt_time_end":"2023-06-26 20:30:00","gmt_time_end_last":"2023-06-26 20:30:00","rrule":null,"timezone":"America\/New_York"},"location":"Kendeda 210","extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"174045","name":"Graduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}