High magnetic field effect in organic light emitting diodes

✍ Scribed by Yuichiro Goto; Takuya Noguchi; Utahito Takeuchi; Kunitada Hatabayashi; Yasushi Hirose; Takayuki Uchida; Takehiko Sasaki; Tetsuya Hasegawa; Toshihiro Shimada

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 464 KB
• Volume: 11
• Category: Article
• ISSN: 1566-1199
• DOI: 10.1016/j.orgel.2010.04.020

✦ Synopsis

Fluorescent and phosphorescent organic light emitting diodes (OLEDs) were measured in high magnetic field up to 9 T. The current efficiency steeply increased below 100 mT as reported but gradually decreased when the field was larger. In the range of 0.1-6.5 T, the decrease was proportional to the square of the magnetic field, whereas in the range between 6.5 and 9 T, it was proportional to the square root of the magnetic field. In contrast, phosphorescent OLED did not show magnetic field dependence. Unipolar devices of n-type Alq 3 (tris-(8-hydroxyquinolino) aluminum) and p-type a-NPD (N 0 ,N 0 -di(naphthalene-1-yl)-N,N 0 -dipheyl-benzidine) showed positive linear magnetoresistance only for minority carriers. The mechanism of the quadratic dependence of the electroluminescent intensity is discussed based on the experimental results.