High magnetic field effect in organic light emitting diodes

• Published in: Organic electronics Vol. 11; no. 7; pp. 1212 - 1216
• Main Authors: Goto, Yuichiro, Noguchi, Takuya, Takeuchi, Utahito, Hatabayashi, Kunitada, Hirose, Yasushi, Uchida, Takayuki, Sasaki, Takehiko, Hasegawa, Tetsuya, Shimada, Toshihiro
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-07-2010; Elsevier
• Subjects: Applied sciences; Efficiency; Electronics; Exact sciences and technology; Magnetic field; Magnetoconductance; Minority carrier; Optoelectronic devices; Organic light emitting diode; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Minority carrier; Magnetoconductance; Efficiency; Magnetic field; Organic light emitting diode; Performance evaluation; Square root; High field effects; Electroluminescence; Aluminium complex; Naphthalene derivatives; Magnetic field effect; p type semiconductor; n type semiconductor; Optoelectronic device; Benzidine; Organic light emitting diodes; Phosphorescence; Magnetoresistance; Organic electronics
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2010.04.020

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 α-NPD (N′,N′-di(naphthalene-1-yl)-N,N′-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.