How to Harness the Power of Light

Mad scientists not only live on campus; they live right down the road in Golden, too. Lauryn Baranowski, researcher at the National Renewable Energy lab, took the opportunity to go into depth as to what actually goes on in the field of cutting-edge research today.

[Oredigger]: What exactly do you do at the national renewable energy lab? Is
there one specific project you work on?

[Baranowski]: Researchers at NREL work on all different technologies and aspects of
renewable energy. This ranges from very basic science, things like
understanding how renewable energy materials and processes work on
atomic scale, to very applied/engineering research, like product
reliability and grid integration of renewable energy technologies. I
work specifically in the area of photovoltaics (PV), or solar cells.
Even though the majority of solar cells you see on rooftops are made
of silicon, there is a really wide variety of materials that we work
on at NREL, ranging from high efficiency cells that operate under very
concentrated sunlight, to flexible plastic solar cells. My specific
project is in the area of “earth-abundant” PV. Many of the record
efficiency cells use expensive, rare, or toxic elements, so it’s
really not possible for these technologies to satisfy a significant
portion of the world’s energy demands. I work on the development of
new PV materials that are made from elements that are cheaper, more
abundant in the earth’s crust, and non-toxic, things like copper, tin,
zinc, iron, sulfur, oxygen, and nitrogen.

What is the major goal of your research?

My major goal is to understand, on atomic level, the workings of the
particular copper tin sulfide materials that I focus on. To know how
to improve a material in a solar cell, you first have to understand,
in detail, how light interacts with the material and how electrons
move within the material. Once I understand this, then I can identify
what needs to be improved about the material in order to make a more
efficient solar cell.

How do you go about actually conducting your research? What type of
data do you collect?

There are a lot of things that I do for research, depending on the
day. Sometimes, I synthesize new samples, which are films of copper
tin sulfide compounds that are about 1-2 micrometers thick (100
micrometers is about the thickness of a human hair). Then, I
characterize these samples to find out what exactly I made, in terms
of the chemical composition and crystal structure, and how well suited
the material is for solar cell applications, by measuring things like
the electrical conductivity and optical (light) absorption. If the
material looks good after this stage, then I take that sample and make
an actual solar cell (which involves lots of other layers/materials),
to test the actual efficiency of the material in a PV cell. If I don’t
think the material properties are suitable for testing in a solar
cell, then I will go back and revise my synthesis parameters (e.g.,
temperature) to try to correct this.

What are some applications of your research, and what fields would benefit the most from this?

The main application of my research is photovoltaics and solar cells.

What are some difficulties encountered in your project? How do you
go about fixing them?

There are lots of different types of problems that I have to deal
with! Sometimes it’s broken equipment, and I might have to figure out
how fix or modify equipment to get it working again. Sometimes it’s
understanding weird or unexpected results. In this case, I might talk
to other scientists that I work with to get their opinion, or read
papers or textbooks to try to understand what is going on. There are
also more abstract problems, like figuring out where to go next with
my research, which requires me to think about what aspects of my work
are most scientifically valuable and interesting.

What is the most enjoyable part of being on the frontier of research? Least-enjoyable?

I think the most enjoyable part of scientific research is having a
really interested scientific question or hunch, and then going into
the lab and actually proving that hunch or answering that question –
it’s really satisfying to be able to do that. Being a NREL is great,
because I get to work with lots of people who are very intelligent and
are passionate about renewable energy. The work load is definitely
high at times, but being a grad student also means that my work
schedule is very flexible.

What have you gained personally from this research?

Obviously I’ve learned a lot about my specific material and the
techniques that I use to synthesize and characterize materials, but I
think the most important things I’ve learned have been much more
broad. Doing research on a graduate level requires that you’re able to
think critically about science, and to come up with creative solutions
to problems that you encounter in your research, and these are skills
that are important no matter where I end up after grad school.

What are your goals for this project in the future?

It would be great if I could optimize my copper tin sulfide materials
and make efficient (on the order of 10%) solar cells. But, if I’m
being realistic, I have to remember that not all projects are
successful in a traditional sense – that’s just the nature of
scientific research. Even if my copper tin sulfide materials don’t
turn out to be good for solar cells, I hope that the understanding
that I’ve gained about this material system can be applied to other PV
materials to further their development.

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