Featured Research

from universities, journals, and other organizations

Electrostatics do the trick: Simple model describes what happens between organic semiconductors and metals

Date:
June 23, 2014
Source:
Helmholtz-Zentrum Berlin für Materialien und Energie
Summary:
Organic semiconductors allow for flexible displays, solar cells, and other applications. One common problem in these devices, however, is the interface between the metallic contacts and the organic semiconductor material, where undesirable losses occur. Now researchers have shown what these losses depend upon.

When inserting an ultrathin dielectric between metal electrode and organic semiconductor, charge carriers (shown here for a positively charged holes in red) are, counter intuitively, more efficiently extracted from their transport level (blue) in the organic to the Fermi level (black) in the metal than without the interlayer.
Credit: M Oehzelt/HZB

Organic semiconductors allow for flexible displays (OLEDs), solar cells (OPVCs), and other interesting applications. One common problem in these devices, however, is the interface between the metallic contacts and the organic semiconductor material, where undesirable losses occur. Now Dr. Martin Oehzelt has shown what these losses between the metal and the organic semiconductors depend upon and how to minimize them. In particular, his model also explains why a thin, electrically insulating layer between the two materials can even facilitate the transition of charge carriers. His results have recently been published in Nature Communications.

Related Articles


Currently, there are many different approaches describing the interface between organic semiconductor materials and metallic contacts. These somewhat contradictory theories, none of which is universally valid for all cases, have now been unified by Oehzelt and developed into a single coherent model based on the electrostatic potential caused by the charge carriers in the metal and the organic semiconductor. "I calculated the impact of the charge carrier distribution on the electronic states at the interface and how these changes feed back onto the charge carrier distribution," he explains. Oehzelt is presently conducting research with Dr. Georg Heimel as a postdoc for Prof. Norbert Koch, who works at the Humboldt-Universität zu Berlin and the Helmholtz-Zentrum Berlin.

Such calculations have never been so comprehensively carried out before. Performing them, Oehzelt states: "it was surprising to me that the quantum physical level was not that important. The electrostatic effects predominated! The agreement between our model and the experimental data were astonishing." On the example of pentacene, a common organic semiconductor, Oehzelt has quantitatively checked the model's predictions for interface losses. The energy distribution of the electronic states in organic semiconductors determines the minimum energy barrier the charge carriers have to overcome in transitioning from or into the metal. The calculation demonstrates that the shape of this energy barrier can vary, from a step-function to slow, continuously rising curves that lead to considerably lower losses. The latter can be achieved by introducing an extremely thin insulating layer between the organic semiconductor and the metal. Contrary to the general expectation, the introduction of an insulator thus improves the electrical contact.

The results of this work could notably simplify optimization of interfaces and contacts and, thereby, the development of more efficient organic electronic devices.


Story Source:

The above story is based on materials provided by Helmholtz-Zentrum Berlin für Materialien und Energie. Note: Materials may be edited for content and length.


Journal Reference:

  1. Martin Oehzelt, Norbert Koch, Georg Heimel. Organic semiconductor density of states controls the energy level alignment at electrode interfaces. Nature Communications, 2014; 5 DOI: 10.1038/ncomms5174

Cite This Page:

Helmholtz-Zentrum Berlin für Materialien und Energie. "Electrostatics do the trick: Simple model describes what happens between organic semiconductors and metals." ScienceDaily. ScienceDaily, 23 June 2014. <www.sciencedaily.com/releases/2014/06/140623104257.htm>.
Helmholtz-Zentrum Berlin für Materialien und Energie. (2014, June 23). Electrostatics do the trick: Simple model describes what happens between organic semiconductors and metals. ScienceDaily. Retrieved January 26, 2015 from www.sciencedaily.com/releases/2014/06/140623104257.htm
Helmholtz-Zentrum Berlin für Materialien und Energie. "Electrostatics do the trick: Simple model describes what happens between organic semiconductors and metals." ScienceDaily. www.sciencedaily.com/releases/2014/06/140623104257.htm (accessed January 26, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, January 26, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Obama Reveals Nuclear Breakthrough on Landmark India Trip

Obama Reveals Nuclear Breakthrough on Landmark India Trip

Reuters - News Video Online (Jan. 25, 2015) — In a glow of bonhomie, U.S. President Barack Obama and Indian Prime Minister Narendra Modi unveil a deal aimed at unlocking billions of dollars in nuclear trade. Pavithra George reports. Video provided by Reuters
Powered by NewsLook.com
NTSB: Missing Planes' Black Boxes Should Transmit Wirelessly

NTSB: Missing Planes' Black Boxes Should Transmit Wirelessly

Newsy (Jan. 23, 2015) — In light of high-profile plane disappearances in the past year, the NTSB has called for changes to make finding missing aircraft easier. Video provided by Newsy
Powered by NewsLook.com
Iconic Metal Toy Meccano Goes Robotic

Iconic Metal Toy Meccano Goes Robotic

Reuters - Innovations Video Online (Jan. 22, 2015) — Classic children&apos;s toy Meccano has gone digital, releasing a programmable kit robot that can be controlled by voice recognition. The toymakers say Meccanoid G15 KS is easy to use and is compatible with existing Meccano pieces. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
The VueXL From VX1 Immersive Smartphone Headset!

The VueXL From VX1 Immersive Smartphone Headset!

Rumble (Jan. 22, 2015) — The VueXL from VX1 is a product that you install your smartphone in and with the magic of magnification lenses, enlarges your smartphones screen so that it&apos;s like looking at a big screen TV. Check it out! Video provided by Rumble
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins