U researchers control electric current, may make organic materials more energy efficient

By Lana Groves, Asst. News Editor

U researchers have recently proved they can control the electric current of an organic material, which can help them test other organic materials to find one that is more energy efficient.

Christoph Boehme, a professor in physics, has been working on the project for the past two years.

“The idea for (the research) comes mostly out of the need to understand what the electron spins in semi conductors do,” he said.

Electrons have magnetic force fields. When the spinning action of the particle can be controlled, the electrical current can also be controlled. Boehme and John Lupton, another lead researcher, tested an organic polymer material and proved that by using a strong magnetic field they can control the state of the spin.

Organic materials are more energy efficient the more times the spin turns.

“What (researchers) have learned is that the spin sometimes slips around by itself,” Boehme said. “They sometimes travel out randomly-completely coincidental.”

When the random spin happens more often, a material is more energy efficient.

Boehme said the spin rarely happens and can only be controlled while in the experiment.

When researchers control how often the spin flips around, they can observe how often the random non-controlled spin flips.

“If you have random spin flips, the oscillation of the current goes up and down,” Boehme said. “The oscillation vanishes when you have random spin flips.”

Boehme said the study can be used to learn what organic materials are more energy efficient by testing different materials.

Inorganic materials are about 40 to 60 percent energy efficient, but cost more to make. Organic materials cost less but are only 10 to 20 percent energy efficient.

Boehme, Lupton and several graduate students who worked on the original experiment will now start testing different organic materials.

Dane McCamey, a postdoctoral student at the U who wrote the study and led many of the experiments, said they designed a device that can hold the organic material and then use it as a semi-conductor.

“At the moment we’re working on aspects (of the device) and making samples,” he said. “(Later) we’re going to do a really systematic study of different parameters and different physical properties that can alter spin flipping, like temperature or combining different materials.”

However, Boehme warns that making organic materials more energy efficient will be difficult.

“I don’t think it would be very possible,” he said. “This is not as straightforward as people thought in the past.”

To produce energy, electrons must emit light.

Boehme said there are four parts of positive and negative electrons, which form into light or heat in a precursor state.

“Only one can produce light and the other three produce heat,” he said. “If, due to a spin flip, they can all go into a state that produces light, they will produce more energy.”

The study will still help researchers understand the connection between the state of a particle’s spin and the semi-conductor.

Manfred Walter, a physics graduate student who contributed to the study, said that the study is very important and will help show how efficient a device can be.

“This study is related to the question ‘How much light can you get out of an organic polymer material?'” Walter said.

The study was published in the journal Nature Materials Aug. 17.

[email protected]