Solution processing for copper indium sulfide solar cells

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In recent years, the field of photovoltaics has become increasingly important due to rising energy demand and climate change. While most solar cells are currently composed of crystalline silicon, devices with thinner films of inorganic absorber materials might allow production at a greater scale due to their lower materials cost. In particular, thin films of CuInS2 are promising solar absorber materials due to their high efficiencies and low required thicknesses. However, the fabrication of thin film solar cells currently requires expensive vacuum techniques. As an alternative, solution-based deposition techniques have been proposed as a route to low-cost and high-throughput electronic device fabrication. I have studied how film growth depends on solutuion deposited precursor film quality, with the goal of producing large grained films of CuInS2 through solution processing. In the first approach, we used solvothermal decomposition of organometallic precursors at moderate temperatures to produce nanoparticles of CuInS2. Thin films of these nanoparticles were cast onto molybdenum coated glass and further processed to create CuInS2 solar cells. We found that performance was dependent on film porosity, grain size, and stoichiometry of the nanoparticles. Films with grain sizes of ~200nm were attained, from which 1.3% efficient solar cells were made. In addition, we showed that this synthesis could be extended to produce CuInS2 nanoparticles with partial substitution of Fe, Zn, and Ga. In the second approach, we synthesized an air-stable hybrid organometallic/nanoparticle ink at room temperature in ambient conditions through a vulcanization reaction. This ink could be coated onto substrates in smooth layers, and further reactive annealing formed large grained CuInS2 films. This process was characterized, and a correlation between residual carbon and grain growth was found. Additionally, the chemical transformation between precursor layers and final sulfide thin film was analyzed, with an emphasis on the difference between sulfurization and selenization. We demonstrated that the sulfurization process was producing morphological defects due to its nucleation limited growth mechanism. However, it was modified to more closely resemble the diffusion limited selenization mechanism, thus producing flat films of CuInS2 with grain sizes of ~500nm.


Type of resource text
Form electronic; electronic resource; remote
Extent 1 online resource.
Publication date 2011
Issuance monographic
Language English


Associated with Connor, Stephen Thacker
Associated with Stanford University, Department of Chemistry
Primary advisor Cui, Yi, 1976-
Thesis advisor Cui, Yi, 1976-
Thesis advisor Chidsey, Christopher E. D. (Christopher Elisha Dunn)
Thesis advisor Stack, T. (T. Daniel P.), 1959-
Advisor Chidsey, Christopher E. D. (Christopher Elisha Dunn)
Advisor Stack, T. (T. Daniel P.), 1959-


Genre Theses

Bibliographic information

Statement of responsibility Stephen Thacker Connor.
Note Submitted to the Department of Chemistry.
Thesis Ph.D. Stanford University 2011
Location electronic resource

Access conditions

© 2011 by Stephen Thacker Connor
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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