Nav: Home

Across the metal-molecule interface: Observing fluctuations on the single-molecule scale

March 08, 2018

Scientists at Tokyo Institute of Technology (Tokyo Tech) have developed a technique for analyzing structural and electronic fluctuations on the single-molecule scale across the metal-molecule interface in an organic electronic device. This technique provides information that cannot be obtained using the conventional method, and it has important implications for devices such as organic solar cells.

The organic electronics field is gaining prominence in both academia and industry as devices such as organic light-emitting diodes and solar cells have multiple advantages over conventional inorganic devices, including much lower potential production costs and broader substrate compatibility. These devices incorporate organic molecules and metal components, and one of the major challenges in this field is understanding the charge transport behaviors across the metal-molecule interface. Recently, break junction techniques were developed, wherein the electric current across a single-molecule junction is measured thousands of times. The measurement results are then analyzed statistically to determine the most probable electrical conductance.

The structural and electronic characteristics of a metal-molecule interface strongly influence the charge transport properties of the single-molecule junction. Further, the metal-molecule interface structures and transport properties fluctuate on the single-molecule scale. Unfortunately, the standard analysis technique of conductance measurement cannot elucidate this behavior sufficiently. Scientists at Tokyo Tech have recently developed a comprehensive method for analyzing these fluctuations. Their technique involves combining two methods: current-voltage measurement through break junction experiments and first-principles simulation. It is worth noting that the developed technique provides a correlated statistical description of the molecular orbital-energy level and the electronic coupling degree across a metal-molecule interface, unlike the standard analysis methods typically employed in this field.

The developed analysis method was applied to various single-molecule junctions, i.e., those of 1,4-butanediamine (DAB), pyrazine (PY), 4,4'-bipyridine (BPY), and fullerene (C60), sandwiched by gold electrodes, and the different molecular-dependent electronic and structural fluctuations were demonstrated. The junctions were stretched by up to 10 nm until breaking during the experiments and simulations in order to identify any structural variations; it was found that the electronic coupling between the electrode and molecule decreases with increased stretching. Further, total energy calculations performed as functions of the stretching distance revealed metastable structures in the structural models.

The developed method provides characteristic information about the simple, low-dimensional, and ultra-small charge transport across the metal-molecule interface, which is relevant to the switching functionality and potential manipulation of transport properties. This novel technique and the information it provides have significant implications for future transport property manipulation in electronic devices featuring organic molecules, such as solar cells and light-emitting diodes.

Tokyo Institute of Technology

Related Solar Cells Articles:

Record efficiency for printed solar cells
A new study reports the highest efficiency ever recorded for full roll-to-roll printed perovskite solar cells.
Next gen solar cells perform better when there's a camera around
A literal ''trick of the light'' can detect imperfections in next-gen solar cells, boosting their efficiency to match that of existing silicon-based versions, researchers have found.
On the trail of organic solar cells' efficiency
Scientists at TU Dresden and Hasselt University in Belgium investigated the physical causes that limit the efficiency of novel solar cells based on organic molecular materials.
Exciting tweaks for organic solar cells
A molecular tweak has improved organic solar cell performance, bringing us closer to cheaper, efficient, and more easily manufactured photovoltaics.
For cheaper solar cells, thinner really is better
Researchers at MIT and at the National Renewable Energy Laboratory (NREL) have outlined a pathway to slashing costs further, this time by slimming down the silicon cells themselves.
Flexible thinking on silicon solar cells
Combining silicon with a highly elastic polymer backing produces solar cells that have record-breaking stretchability and high efficiency.
Perovskite solar cells get an upgrade
Rice University materials scientists find inorganic compounds quench defects in perovskite-based solar cells and expand their tolerance of light, humidity and heat.
Can solar technology kill cancer cells?
Michigan State University scientists have revealed a new way to detect and attack cancer cells using technology traditionally reserved for solar power.
Solar cells with new interfaces
Scientists from NUST MISIS (Russia) and University of Rome Tor Vergata found out that a microscopic quantity of two-dimensional titanium carbide called MXene significantly improves collection of electrical charges in a perovskite solar cell, increasing the final efficiency above 20%.
Welcome indoors, solar cells
Swedish and Chinese scientists have developed organic solar cells optimised to convert ambient indoor light to electricity.
More Solar Cells News and Solar Cells Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Warped Reality
False information on the internet makes it harder and harder to know what's true, and the consequences have been devastating. This hour, TED speakers explore ideas around technology and deception. Guests include law professor Danielle Citron, journalist Andrew Marantz, and computer scientist Joy Buolamwini.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.