@article{Design:2077,
      recid = {2077},
      author = {Hudson, Margaret Hervey},
      title = {Design, Control, and Characterization of  Solution-processed Semiconductors for Optoelectronic  Applications},
      publisher = {University of Chicago},
      school = {Ph.D.},
      address = {2019-12},
      pages = {180},
      abstract = {The deposition of functional semiconducting materials from  solution and processing under mild conditions can lower  manufacturing costs and expand device versatility. In this  document, we examine three classes of solution-processable  inorganic semiconductors to gain a better understanding of  these materials and plan a route for their optimization.  Chapters 2 and 3 focus on the characterization and  applications of chalcogenidocadmates, soluble precursors  for II-VI semiconductors. Single crystal x-ray diffraction  and extended x-ray absorption fine structure (EXAFS)  measurements allow us to elucidate the molecular structure  of Na2Cd2Se3 in its solid state and in hydrazine solution.  We explore cation exchange of this species to expand its  solubility from hydrazine to more benign solvents and use  the cation exchanged selenocadmate to stabilize CdSe  nanocrystals in NMF. In Chapter 3, we modify the  chalcogenidocadmate structure through interaction with  micelle-forming organic cations to create templated  mesostructures of CdSe and CdTe. We also show that the  reaction of selenocadmate with Cd2+ creates a  stoichiometric CdSe gel which can be annealed under mild  conditions to form photoconductors or field effect  transistors.

In the final chapters of the document, we  shift our focus away from molecular semiconductor  precursors and instead explore colloidal semiconductor  nanocrystals, or quantum dots (QDs). HgTe QDs have tunable  absorbance across the infrared and can be used as the  active layer in mid-infrared photodetectors. In Chapter 4,  we use precise synthesis, chemical control of ensemble  doping, optical characterization, and electrochemical  studies to show that the intraband absorbance of  electron-doped HgTe QDs has three peaks, which correspond  to transitions between the 1Se state and three  nondegenerate Pe states.

In Chapter 5, we study several  parameters in the molten salt synthesis of In1-xGaxP QDs.  The emission energy of these QDs can be tuned by both QD  size and alloy composition. We show that the QD surface  chemistry can be designed to improve the QD phase stability  at elevated temperature. Additionally, we explore a variety  of reaction conditions to show that indium-to-gallium  cation exchange is diffusion controlled and is accompanied  by surface recrystallization. These insights will be useful  in designing cation exchange conditions to achieve a  desired alloy composition.},
      url = {http://knowledge.uchicago.edu/record/2077},
      doi = {https://doi.org/10.6082/uchicago.2077},
}