Evaluating Organic Light-Emitting Diodes for Position-Sensitive Magnetic Field Sensing

Magnetic sensors offer versatile applications across a broad range of industries. This project investigates thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLED) as a potential sensor for position-sensitive mapping in low (micro to milli Tesla) magnetic fields. These fields are mapped using the spatial variation in light intensity of the OLED resulting from the variations in exciton formation and population dynamics under a magnetic field. The exciton-based sensing modalities of these devices are evaluated by taking measurements of magneto-electroluminescence (MEL) and magnetoresistance (MR) while interacting with an external magnetic field. Comparing the light intensity of devices under differing external magnetic fields through optical imaging, the spatial resolution in light output is assessed as a method for magnetic field mapping of a layer of magnetic film or magnetic nanoparticles on an OLED. Furthermore, in conducting a life span study in a nitrogen gas glovebox, it is observed that OLEDs will better preserve device characteristics and maintain magnetic field sensitivity when encapsulated. Implications of this study on OLEDs for position-sensitive magnetic field sensing suggest that these devices could be used as an alternative option compared to traditional sensors.