Kenneth (Xerxes) Steirer
Research Associate Professor, Department of Physics
Already an experienced photographer and chef, I re-entered college to help improve sustainability of society through STEM. I began experimental research in the summer of 2004 with Professor David Braun, a former post-doc of Nobel Prize winning Alan Heeger. During my graduate work, I spent most of my time at the National Renewable Energy Laboratory under the supervision of Dr. David Ginley developing new processes for functional thin films and coatings. As a post-doc at the University of Arizona working for Professor Neal Armstrong, I acquired a deep respect for ultra-high vacuum analytical techniques as well as new methods of film growth. A competitive position as an NREL Director’s Postdoctoral Fellow brought me back to Colorado where my expertise as a surface scientist grew immensely under the mentorship of Dr. Craig Perkins and many other NREL scientists. Now a the Colorado School of Mines, I enjoy facilitating student learning on several of our most advanced materials characterization equipment. At home, I enjoy my family, our urban farm, and leading several sustainability efforts in the city of Edgewater, Colorado.
Already an experienced photographer and chef, I re-entered college to help improve sustainability of society through STEM. I began experimental research in the summer of 2004 with Professor David Braun, a former post-doc of Nobel Prize winning Alan Heeger. During my graduate work, I spent most of my time at the National Renewable Energy Laboratory under the supervision of Dr. David Ginley developing new processes for functional thin films and coatings. As a post-doc at the University of Arizona working for Professor Neal Armstrong, I acquired a deep respect for ultra-high vacuum analytical techniques as well as new methods of film growth. A competitive position as an NREL Director’s Postdoctoral Fellow brought me back to Colorado where my expertise as a surface scientist grew immensely under the mentorship of Dr. Craig Perkins and many other NREL scientists. Now a the Colorado School of Mines, I enjoy facilitating student learning on several of our most advanced materials characterization equipment. At home, I enjoy my family, our urban farm, and leading several sustainability efforts in the city of Edgewater, Colorado.
Education
- PhD, Applied Physics, Colorado School of Mines
- BS, Physics, California Polytechnic State University-San Luis Obispo
Teaching and Mentoring
Sustainability and STEM offer two overlapping areas of study with fascinating and profound impacts on our society. While I can lecture all day on surface science, my joy of teaching emerges from helping students connect with the broader concepts and their journey towards employment.
I enjoy working with students who bring their ideas and curiosity to discover new things. While my passions orbit around surface science, I encourage students to explore all aspects of discovery and innovation, from fundamental physics and chemistry to the processes of patenting and invention.
Research
My areas of expertise bridge several areas of physics and chemistry. Beginning my career in organic semiconductor processing and device physics, I have found amazing utility in the electronic and chemical aspects of interface formation and operation, thin film growth and processing and vacuum based methods. Think of the organic light emitting devices now found in the most impressive displays and many interfaces which must satisfy power, performance and durability requirements. Vacuum science played a huge role in the development of this and many other advanced device architectures. In vacuum, the ambient variables may be completely controlled for, ensuring a robust testing of physical and chemical hypotheses. Whether we’re testing a newly synthesized molecular material or optimizing an oxide thin film growth process, we seek approaches to add depth to the analysis in ways that are fundamental in nature.
Here is an example of how one of my favorite vacuum science methods, photoelectron spectroscopy (PES) in its pure form, can provide new information on an important material that is changing under the X-rays. From PES, methyl ammonium lead triiodide (an important solar material) composition is measured repeatedly over 40 hours. During that time the I concentration is observed to decrease relative to Pb (left to right in the figure). However, the electronic properties are invariant as evidenced by the lack of shift in the valence band edge. It is not until a significant fraction of I (as well as C and N) has left the material that the system begins to transform into lead iodide. Electronic structure modeling shows that these types of defects fall outside the bandgap and self compensate. This is the first experimental observation of high defect tolerance for this material, which is helping to explain its incredible performance in solar cells. Steirer et al. ACS Energy Lett., 2016, 1 (2), pp 360–366
