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Laser Spectroscopic Studies of Ultrafast Charge Transfer Processes in Solar Cell Materials

Kolodziej, Charles

Abstract Details

2020, Doctor of Philosophy, Case Western Reserve University, Chemistry.
The need for alternative energy sources has been growing in the last decade or so. With an ever-increasing population and a strong consumer culture, particularly in the United States, the current energy sources are becoming difficult to obtain and are filling the Earth’s atmosphere with pollutants. My work has been focused on investigating structure-function relationships in photovoltaic materials, specifically their optoelectronic response. One of the materials I have studied is methylammonium lead iodide, a hybrid organic-inorganic perovskite that finds application in many fields, such as light emitting diodes, laser dyes, and superconductors. As photovoltaics, they are usually deposited onto a substrate to form a thin, polycrystalline film, sandwiched by electron and hole transport materials. Perovskites can be formed using many different compositions, which affect its ultimate surface morphology and electronic performance. I created a set of perovskite morphologies and compositions with the aim to learn more about how a different surface morphology and an additive will influence the charge carrier movement in perovskite films. Two different morphologies, granular and fibrous, showed that film morphology is not as important in material performance as is the compositional homogeneity throughout the film and that long photoluminescence lifetime is influenced by sub-band edge states. Addition of chloride into the methylammonium lead iodide films results in films with very low concentrations of chloride, but still produces a change in the morphology of the film. The optoelectronic behavior did not change homogenously or drastically throughout the film, but appeared as trap states in localized areas. This supports other’s findings that chloride does not directly influence perovskite’s performance, and is instead a morphological influence. I have also investigated a benzannulated iron(II)-based complex showing exceptionally long-lived charge transfer states. Additionally, it has a broad absorption range from the UV to 900 nm, matching well with the solar spectrum. The design scheme of the complex is proposed as an alternative to precious metal based designs, and to extend iron complexes’ charge transfer lifetimes from the picosecond into the nanosecond range. Summarily, this work presents findings relevant to the energy materials field by investigating structural, compositional, optical, and electronic properties.
Clemens Burda (Advisor)
Carlos Crespo-Hernández (Committee Chair)
Geneviève Sauvé (Committee Member)
Shane Parker (Committee Member)
Lydia Kisley (Committee Member)
168 p.

Recommended Citations

Citations

  • Kolodziej, C. (2020). Laser Spectroscopic Studies of Ultrafast Charge Transfer Processes in Solar Cell Materials [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1586371698913592

    APA Style (7th edition)

  • Kolodziej, Charles. Laser Spectroscopic Studies of Ultrafast Charge Transfer Processes in Solar Cell Materials. 2020. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1586371698913592.

    MLA Style (8th edition)

  • Kolodziej, Charles. "Laser Spectroscopic Studies of Ultrafast Charge Transfer Processes in Solar Cell Materials." Doctoral dissertation, Case Western Reserve University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1586371698913592

    Chicago Manual of Style (17th edition)