In the face of the world energy crisis and climate change, solar energy is the leading potential resource that can ensure a sustainable energy source free from carbon emission which is also capable of being produced for generations to come. Among the next generation solar cells, organo-inorganic mixed halide perovskite solar cells (OIHPSCs) and quantum dot sensitized solar cells (QDSSCs) show promises towards this goal. OIHPSCs have recently drawn plenty of attention due to their low cost and extraordinary power conversion efficiency performance. The efficiency of the solar cells using Pb-based perovskites increased from ~3 % in 2009 to ~21.1 % in 2016. On the other side, the efficiency of quantum dot sensitized solar cells has increased more slowly, 12%, on roughly the same time scale. Many different techniques have been used to improve device performance and overall efficiency. One way to improve the efficiency is to tailor the band-gap of the device materials to be most suitable for charge separation and conduction. There exist many ways to tailor a material’s band-gap: one example is changing the stoichiometric ratio of the halides in an OIHP, another example is introducing dopants, more specifically Mn dopants in semiconducting QDs. Understanding how the stoichiometry of a solar cell material or how a dopant influences the band structure are a couple paths toward better band-gap tailoring and thus achieving higher efficiency photovoltaics. In this dissertation the use of scanning tunneling microscopy in conjunction with a suite of other characterization tools to study the microscopic electronic band structure in an OIHP and in several Mn doped QD systems will be discussed.
|Commitee:||Dahnovsky, Yuri, Pikal, Jon, Tang, Jinke, Zhou, Jing|
|School:||University of Wyoming|
|Department:||Physics & Astronomy|
|School Location:||United States -- Wyoming|
|Source:||DAI-B 78/12(E), Dissertation Abstracts International|
|Subjects:||Physics, Condensed matter physics|
|Keywords:||Organic-inorganic halide perovskites, Quantum dots, Scanning tunneling microscopy, Solar cell|
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