Quantum mechanism breakthrough for thin film solar and OLED lighting displays

January 18 2009 / by Garry Golden
Category: Energy   Year: 2018   Rating: 2

MoleculesEnergy is driven by interactions of light, carbon, hydrogen, oxygen and metals

At least, that's the simple explanation.

The closer the human mind gets to understanding and controlling quantum behavior of light and molecules, the more likely we are to enable an era of cheap abundant energy.

Now, thanks to work by a research team led by University of Toronto's Greg Scholes  and Elisabetta Collini, we are a step closer to understanding (and controlling) how light moves along long carbon-based molecular chains to create an electrical charge.

Organic Electronics - Thin Film solar & OLEDs
Their research could lead to advances in the emerging field of 'organic' electronics (carbon based electronics) that support thin film solar cells and batteries, and flexible transparent OLED display screens.

The group has focused on 'conjugated polymers' as a promising candidate for building efficient organic solar cells.  These long chains repeat the same molecule patterns and can be maniuplated to mimic the properties of traditional silicon based semiconductors.

When these materials absorb light, the energy moves along the molecular chain ('polymer') ending in an electrical charge.

"One of the biggest obstacles to organic solar cells is that it is difficult to control what happens after light is absorbed: whether the desired property is transmitting energy, storing information or emitting light," Collini explained. "Our experiment suggests it is possible to achieve control using quantum effects, even under relatively normal conditions."

Humans being creating Quantum-mechanical mechanisms

"We found that the ultrafast movement of energy through and between molecules happens by a quantum-mechanical mechanism rather than through random hopping, even at room temperature," Scholes explained.

"This is extraordinary and will greatly influence future work in the field because everyone thought that these kinds of quantum effects could only operate in complex systems at very low temperatures," he said.

Scholes and Collini´s discovery has significant implications for quantum computing because it suggests that quantum information may survive significantly longer than previously believed.

In their experiment, the scientists used ultrashort laser pulses to put the conjugated polymer into a quantum-mechanical state, whereby it is simultaneously in the ground (normal) state and a state where light has been absorbed. This is called a superposition state or quantum coherence. Then they used a sophisticated method involving more ultrashort laser pulses to observe whether this quantum state can migrate along or between polymer chains.

"It turns out that it only moves along polymer chains," Scholes said. "The chemical framework that makes up the chain is a crucial ingredient for enabling quantum coherent energy transfer. In the absence of the chemical framework, energy is funnelled by chance, rather than design.

According to Scholes, "This means that a chemical property -- structure -- can be used to steer the ultrafast migration of energy using quantum coherence. The unique properties of conjugated polymers continue to surprise us."

 

The research was funded by the Natural Sciences and Engineering Research Council of Canada.

Eureka Alert

University of Toronto Press Release - Materials Cited

 

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