Spin Response in Organic Light Emitting Diodes
Abstract
To understand the origin of the magnetic field effect in OLEDs, we studied the large magnetoresistance (MR) and magnto-electroluminescence (MEL) of OLEDs based on pristine MEH-PPV polymer, as well as MEH-PPV doped with various concentrations of radical impurities and C60 molecules. In contrast to OLED based on pristine MEH-PPV that show MR and MEL up to 12% at room temperature, we found in MEH-PPV:C60 based OLED the MR and MEL decrease substantially with increasing C60 molecule concentration. For MEH-PPV:C60 devices with C60 concentration of 50%, the MR effect is less than 0.3% at room temperature. In MEH-PPV: radical devices the MR and MEL effects again differ substantially from those found in pristine and C60 doped MEH-PPV devices. At 50% radical concentration the MR and MEL effects are about 1% and 3.5%, respectively. The results are discussed with existing models for the magnetic field effects in OLEDs.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2008
- Bibcode:
- 2008APS..MARW22008W