15 Sep 2014

Fe2GeS4 Nanocrystals for Photovoltaics

Literature Discussion

Submitted by Anne Bentley, Lewis & Clark College
Categories
Description: 

I asked the students in my junior/senior inorganic course to develop their own literature discussion learning objects and lead the rest of the class in a discussion of their article.  Student Johann Maradiaga chose this article describing the synthesis and characterization of Fe2GeS4 nanocrystals with potential applications in photovoltaic devices (Sarah J. Fredrick and Amy L. Prieto, “Solution Synthesis and Reactivity of Colloidal Fe2GeS4: A Potential Candidate for Earth Abundant, Nanostructured Photovoltaics” J. Am. Chem. Soc. 2013, 135, 18256-18259. DOI: 10.1021/ja408333y).  The article describes the synthesis in hexadecylamine/octadecene of Fe2GeS4 nanoparticles and their characterization using powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and photocurrent measurements.  Building on Johann’s original set of questions, I developed this literature discussion, which is suitable for use in inorganic chemistry courses. Many thanks to article author Sarah Fredrick for reviewing the assignment and adding some great questions.

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File Fe2GeS4 nanocrystals.docx784.38 KB
Learning Goals: 

After reading and discussing this paper, a student will be able to:

  • Understand how variable growth rates along different crystal planes result in specific shapes, and predict a resulting shape given a particular set of growth rates
  • Compare the oxidation behavior of Fe and Ge over time using XPS data
  • Describe a photocurrent measurement experiment and compare the photocurrent behavior of p-type and n-type semiconductors.
  • Explain the value of a communication as compared to a longer research article

 

Implementation Notes: 

Students do not need to be experts to understand this article, but previous exposure to solid state concepts including semiconductor electronic structure, solid state phases, nanoparticle synthesis, and capping agents will be helpful to them.  Alternatively, the article could be used to introduce these topics.

This JACS communication is fairly short and written clearly, so it could make a good first literature discussion for students without previous experience reading journal articles.

I have included a large number of possible questions in the literature assignment, but as always, users should feel free to pick and choose from the options and/or add their own.

Time Required: 
45 minutes (approximately)
Evaluation
Evaluation Methods: 

My student led a 20-minute class discussion of this article in the spring of 2014.  The other students in the class were asked to post two questions about the article to moodle before the class meeting, but they were not asked to complete the literature discussion questions due to assignment overload at the end of the semester.

Evaluation Results: 

The six students posted good questions about the article, some of which I have incorporated into the literature discussion. One student asked why Ge was used instead of Si.  (My guess is that Si is too prone to oxidation - it's consistent with redox potentials.)  Another student wanted to know if any articles had been published after this one describing further progress.  At least two asked how the authors could determine that the photocurrent was p-type.

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