Magnetic field effects on the electroluminescence of organic light emitting devices: A tool to indicate the carrier mobility

Abstract

The magnetoelectroluminescence (MEL) of organic light emitting devices with a N,N′-bis(l-naphthyl)-N,N′-diphenyl-1,l′-biphentl-4,4′-diamine:tris-(8-hydroxyquinoline) aluminum (NPB:Alq3) mixed emission layer (EML) has been investigated. We find that MEL is maximized when the volume ratio of NPB of the mixed EML reaches 30% and the EML thickness is 40 nm. The features of MEL under various magnetic field strengths are insensitive to the change in EML thickness and mixing ratio. Meanwhile, MEL has a close relationship with the carrier mobility. We have conducted a theoretical study to further verify the relationship. Our experimental and theoretical results confirm that MEL can function as a tool to indicate the mobility.

Using Magneto-Electroluminescence As a Fingerprint to Identify the Carrier-to-Photon Conversion Process in Dye-Doped OLEDs

“…It is a competition between the local and nonlocal effects that determines the intensity of MEL for many systems. 22,28,29 Because of the higher current efficiency shown as the inset of Figure 1b, C540-doped OLED requires lower driving voltage to achieve the same brightness that the control OLED does. At the same time, a lower applied voltage leads to lower carrier mobility…”

Magnetoresistance in electrochemically deposited polybithiophene thin films

“…Light-emitting diodes, solar cells, and transistors among others [1] can be mentioned to illustrate their most spread applications. More recently, several groups reported the sensitivity of organic materials to magnetic fields, widening their range of applicability and instigating scientists' curiosity about its origins [2][3][4][5][6][7][8][9][10][11][12][13][14]. One of the studied characteristics is magnetoresistance (MR), which relates the dependence of resistance to an applied magnetic field on the material when using non-magnetic electrodes to monitor current-voltage signal, often called organic magnetoresistance (OMAR).…”

Energy level alignment and interactive spin polarization at organic/ferromagnetic metal interfaces for organic spintronics

“…One is organic magnetoresistance (OMAR), 3 usually accompanied by magnetoluminescence. 4,5 It occurs in conventional OSCs electronic devices with non-magnetic electrodes. This type of intrinsic magnetoresistance is believed to be connected to various excited states in OSCs, 6 and, as evident from the lack of magnetic electrodes, has nothing to do with spinpolarized charge injection.…”