Halide perovskite materials have emerged in the past few years as promising materials in the absorption layer of photovoltaic cells and
new emissive materials for use in light emitting diodes (LEDs). This is due to their rapidly increasing efficiencies and brightness. In
photovoltaic applications they show promise to lower cost and improve efficiency of photovoltaic cells. Their low temperature processability
also may lead to interesting new applications in existing solar cell technologies. In LED applications, they exhibit other desirable properties
such as color tunability, simple device structures, and facile processability. However, a common problem that is observed in perovskite thin
films is a hysteresis in their I-V characteristics, and short device lifetimes. It is hypothesized this is due to ion migration within the
crystal and along the grain boundaries between crystals. This thesis addresses this issue by exploring methods to restrict ionic motion. One
highly promising method was controlling nucleation to reduce the grain boundary density in the perovskite thin films. A deterministic nucleation
process was developed using standard lithography techniques to prepattern a substrate followed by solution processing of the halide perovskite
layer. It was found the grain size, grain boundary density, and final crystal shape could be well controlled using this process. In addition, it
was found the hysteresis behavior was well controlled, and the stability of the final film was increased due to lower grain boundary density. In
addition, further methods to restrict ionic motion were explored using Ruddlesden-Popper perovskites that form a quasi 2D structure. These
perovskites were examined and characterized due to their ability to restrict ionic motion within the perovskite crystal. These perovskites also
allowed for further flexibility in tuning device electrical and optical properties and offered greater stability compared to their 3D
counterparts. / A Dissertation submitted to the Program in Materials Science and Engineering in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. / Fall Semester 2018. / November 5, 2018. / 2D Materials, Grain Boundaries, Halide Perovskites, Optoelectronics / Includes bibliographical references. / Zhibin Yu, Professor Directing Dissertation; John Telotte, University Representative; Kenneth Hanson,
Committee Member; Zhiyong Richard Liang, Committee Member; Yan-Yan Hu, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_661138 |
| Contributors | Geske, Thomas Scott (author), Yu, Zhibin (professor directing dissertation), Telotte, John C. (university representative), Hanson, Kenneth G. (committee member), Liang, Zhiyong (committee member), Hu, Yan-yan (committee member), Florida State University (degree granting institution), Graduate School (degree granting college), Program in Materials Science (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (143 pages), computer, application/pdf |
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