Due to the unique chemical structure, the particles arrange themselves in a sort of spiral. The result: The electron-conducting core is protected, which causes higher performance of the organic light-emitting diode. Credit: MPI-P
New product principle gets rid of the unwanted effects of impurities in organic light-emitting diodes.
Researchers at the Max Planck Institute have actually created a new particle structure that boosts the effectiveness of blue OLEDs. Their advancement can simplify the design and production procedure of these OLEDs.
Organic light-emitting diodes (OLEDs) have actually become a typical function in numerous modern-day gadgets, from tvs to mobile phones. In order to display an image, OLEDs require to forecast light in the three main colors: red, green, and blue. Notably, the production of light-emitting diodes for blue light is particularly challenging due to its high-energy physical homes, which complicate the advancement of suitable materials.
Due to the unique chemical structure, the particles organize themselves in a kind of spiral. Such pollutants, like oxygen molecules, hamper the motion of electrons within the diode, interfering with the light-generation process. These molecules make up two chemical parts: one part helps with electron conduction, while the other part is not delicate to pollutants. By controling the chemical structure of the molecule, a special spatial arrangement is achieved: When several molecules are signed up with, they form a kind of “spiral”– that indicates the electron-conducting part of the particles forms the inner part, which is protected on the outside by the other part of the molecules.
A considerable aspect in the performance of these products is the presence of small quantities of pollutants that are difficult to entirely eliminate. Such pollutants, like oxygen molecules, restrain the movement of electrons within the diode, interfering with the light-generation procedure. When an electron is trapped by these pollutants, its energy is transformed into heat instead of light. This phenomenon, referred to as “charge trapping,” primarily affects blue OLEDs, causing a considerable decrease in their performance.
A group led by Paul Blom, director at limit Planck Institute for Polymer Research, recently addressed the problem of charge trapping by using a new class of molecules. These particles make up 2 chemical parts: one part facilitates electron conduction, while the other part is not sensitive to pollutants. By controling the chemical structure of the molecule, a special spatial plan is accomplished: When numerous molecules are signed up with, they form a type of “spiral”– that implies the electron-conducting part of the particles forms the inner part, which is shielded on the outdoors by the other part of the particles. This resembles, in a molecular way, a coaxial cable television with an electron conducting inner core and an outer part protecting the core.
The cladding thus forms a kind of “protective layer” for the electron-conducting core, shielding it from the intrusion of oxygen particles. Thus, the electrons can move quick and freely along the main axis of the spiral without being caught by challenges, similar to cars and trucks on a highway without crossings, traffic lights or other obstacles.
” One of the special features of our new material is that the lack of losses due to impurities and resulting efficient electron transport can significantly streamline the design of blue OLEDs, while preserving a high effectiveness,” says Paul Blom.
With this innovative technique, the researchers want to considerably streamline the production of blue light-emitting diodes. Their results have been published in the journal Nature Materials, marking an important stride towards the development of OLED technology.
Recommendation: “Elimination of charge-carrier trapping by molecular style” by Oskar Sachnik, Xiao Tan, Dehai Dou, Constantin Haese, Naomi Kinaret, Kun-Han Lin, Denis Andrienko, Martin Baumgarten, Robert Graf, Gert-Jan A. H. Wetzelaer, Jasper J. Michels and Paul W. M. Blom, 29 June 2023, Nature Materials.DOI: 10.1038/ s41563-023-01592-3.