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Fabrication of Nanostructure Cuprous Oxide Films for Photovoltaic Systems

Shooshtari, Leyla | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51060 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Iraji Zad, Azam; Mohammadpour, Raheleh
  7. Abstract:
  8. Metal oxide semiconductors are promising materials for photovoltaic systems, because they are chemically stable, almost non-toxic and abundant. These materials are cheap and have low cost fabrication process. Cu2O is the most popular metal oxide semiconductor to absorb light in Photovoltaic (PV) applications, and photocathode in the photoelectrochemical systems.In this project, thermal oxide and electrodeposition methods, both interesting and cheap, were applied for preparing Cu2O films. As inexpensive materials results in low-minority carrier diffusion length, we report on surface engineering of bulk Cu2O photocathode thorough employing nanorods of copper oxide with the average lengths of 150 nm. These nanostructures have been synthesized by anodization of Cu foil in aqueous KOH electrolyte, followed by annealing treatment at 700 °C. In comparison to the bulk Cu2O thermal oxidized electrode, photoelectrochemical analysis indicates that nanorod/bulk Cu2O electrodes have noticeable enhancement in photocurrent, of about 76% at -0.6V vs. Ag/AgCl, and the favorable decrease of about 103 Ω in interface resistance.For optoelectronic devices, estimating the dopant densities of the film is necessary. As Cu2O is easily reduced or oxidized to Cu or CuO in aqueous solutions, the novel electrolyte for electrochemical analysis of Cu2O, including Mott-Schottky (MS) and impedance spectroscopy (IS), were performed in non-aqueous electrolyte based on tetrabutylammonium-tetrafluoroborate in 3-methoxypropionitrile. The obtained results, in terms of dopant density and flat band potential, are reproducible.The solar cells prepared by Cu2O layers through thermal oxidation, provides the highest efficiency of around 0.55% through the AZO/ZnO/Cu2O structure; in which the electron transport layers prepared by r.f sputtering method. The solar cells through the bare structure of FTO/ZnO/Cu2O were also fabricated in this project, in which ZnO prepared by electrodeposition method. The efficiency through inserting the SnS2, Zn:Cu2O and Cu2O nanosphere depositions, as buffer layers, improved about 50%, 36% and 85% respectively against to the bare structure.The pervoskite solar cell based on Cu2O as a hole transported layer, with the thinnest thickness, provides around 2.14% efficiency.
  9. Keywords:
  10. Thermal Oxidation ; Electrodeposition ; Copper Oxide ; Photoelectrochemical Cell ; Bulk Heterojunction ; Photovoltaic System ; Nanostructured Coating ; Mott-Schottky Analysis ; Oxidized Solar Cell

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