Ask the experimentalist.

I notice in GQ and GD that many of the dopers there seem to have a background in the theoretical sciences.

In order to break up the monotony of writing my doctoral thesis I decided to try and answer as many questions as I can regarding the work in my area and others if I can.

I am an experimentalist working in, what can only be described as, a grey area between physics and chemistry; organic electronics. I am fabricating organic photovoltaic devices with a variety of polymers and nanomaterials with a view to improving the efficiency of such devices.

The work involves having a good knowledge of semi-conductor physics and I have had to pick up a smattering of organic chemistry as well from a theoretical point of view.

From a practical viewpoint I get to carry out a number of processes and use a wide range of fabrication and characterisation techniques including; RF sputtering, spin coating, plasma etching and electrical measurements, AFM and SEM imaging and various types of spectroscopy (FTIR and UV-Vis mainly).

Although I will be on leave for the next week, I am happy to answer any questions you have and will reply ASAP.

Walker.

Any comments on approaches or experiences in setting up isolated environments? I’m an engineer and do the writing and designing, but all the “touch” work gets passed on to labs and manufacturers.

I’ve always been incredibly in awe of how you lab folks can isolate experiments and remove secondary effects, noise, contamination, etc and still get usable results. All it takes is one grad student sneezing a crumb of their egg salad sandwich into the air…

Don’t know enough about the topic to ask a question. :frowning:

Where does the organic portion come in?

What specifically is the role of the polymers and nanomaterials?

how close are we to using single layer graphene in high efficiency solar cells. In layman’s terms, what are the obstacles and can they be overcome?

Thanks.

I’ll answer this first as it’s the easiest to answer.

The organic portion is the polymer, they are not organic in the sense of being living materials, but are hydrocarbons, which are generally called organic molecules by chemists.

The role is fairly easy to describe too. Incoming photons excite the polymer and create a virtual particle called an exciton (a coulomb bound electron-hole pair). This then can dissociate into a free electron and a hole. The nanoparticles serve two purposes; firstly they create a boundary for the exciton to dissociate at and secondly they act as electron acceptors so that the free electrons can “hop” from particle to particle until they reach the electrode.

Many organic photovoltaic devices are a blend of polythiophenes and C60 (buckyballs), by adding additional naoparticles to the blend we hope to modify certain characteristics of the material and improve the overall efficiency. Sadly I can’t mention which nanoparticles at present as we are hoping to publish it and if I let the cat out of the bag it will diminish our chances.

do you consider science work or complex/intense/difficult play?

A bit of both really. Although at present I am just finishing my PhD, whether there is a job available in a few months is unclear due to the UKs current financial state.

The best part of the job is that I get to use some pretty interesting equipment, RF sputterers, thermal evaporators, spin coaters, atomic force microscopes, electron microscopes and a variety of spectroscopic equipment.

I’ve also picked up a bit of a talent for fixing high vacuum equipment, which is a fun if not very saleable skill.

Graphene is not my area of expertise, but the greatest problem that I am aware of with graphene is that it is difficult to manufacture in large areas which would be necessary for a commercially viable solar cell.

Many of the methods for producing graphene, other than the “scotch tape method” require high vacuums and temperatures to grow the films on a substrate. This does not lend itself to coating large surgace areas of substrate due to the cost and energy use of the chamber necesary to contain it. Hopefully one day someone will come up witha suitable method.

We have a Class 100 clean room, not quite perfect, but it serves our needs. Everything is cleaned regularly and the air is constantly pumped out and filtered. This still does not completely eliminate dust in the fabrication process, so the best approach is to make multiple devices to a substrate so that even if one (or more) fails there are others that can be used. As the organic polymers I use tend to absorb water and oxidise readily it would be betetr if we could make the devices in a neutral atmosphere like nitrogen. We are still trying to get funding to do this.

In testing noise is not an issue, but light is. All of our testing takes place in a closed box with a solar light source (AM 1.5).