Clark, Catherine2021-10-132021-10-132020-08https://hdl.handle.net/11299/224943University of Minnesota Ph.D. dissertation. August 2020. Major: Material Science and Engineering. Advisor: Russell Holmes. 1 computer file (PDF); xvi, 252 pages.Metal halide perovskites (MHPs), like the archetypal methylammonium lead iodide (MAPbI3), have emerged in the last decade as promising materials for efficient, low-cost optoelectronics. MHP solar cells have already reached efficiencies >25%, rivaling established technologies like single-crystal Si. Yet several challenges prevent the widespread commercialization of MHPs, including their instability in ambient conditions, their toxicity, and the need for scaleable fabrication techniques. Fundamentally, the origins of important material properties relating to carrier transport and recombination are still not well understood. Thin film deposition techniques that enable detailed study of process-structure-property relationships and are commercially relevant are consequently becoming increasingly essential. This thesis seeks to address these challenges through the design, implementation, and utilization of a carrier-gas assisted vapor deposition (CGAVD) method that can grow MHP films with highly tunable stoichiometries and morphologies. Alongside the design of a CGAVD system with six independently controllable experimental parameters, an analytical model is developed and experimentally validated that allows the determination of robust and repeatable growth regimes and the prediction of material deposition rates. Harnessing this technique, we demonstrate the ability to deposit MASnI3 and MASnBr3 films and to systematically vary their compositions across a wide range, and realize corresponding changes in film microstructures (grain size, coverage) and electronic properties (resistivity, carrier concentration, mobility). Control of grain size and film texturing is also achieved independent of stoichiometry via modulation of chamber pressure and substrate temperature. The benefits of CGAVD are further highlighted by the successful growth of novel all-MHP heterojunctions. Two stable pairings are identified: MAPbBr3/MASnBr3 and CsPbBr3/MASnBr3. Design rules to control the mixing of heterojunctions are developed by exploring the dependence of mixing rate on MHP layer composition and grain size. Finally, through a collaboration with Physical Electronics, we optimize the use of XPS depth-profiling for MHPs and investigate which ions are diffusing in a layered structure that exhibits mixing. Moving forward, the incorporation of CGAVD-grown heterojunctions and Pb MHPs into optoelectronic devices will harness the tunability of this system towards a deeper understanding of process-structure-property relationships in MHP thin films and novel layered structures.enOptoelectronicsPerovskitesPhotovoltaicsSolar CellsThin FilmsVapor DepositionThesis or Dissertation