Magnetic Field Sensor Based on a OLED/Organic Photodetector Stack

In this study, an all-organic magnetic field sensor based on an organic light-emitting diode (OLED) and organic photodetector (OPD) layer stack is presented. This sensor opens possibilities to create printable, flexible magnetic field sensors using commercially viable components, allowing magnetic field sensors to be simply integrated into the existing OLED technology. The sensor function is driven by the large magneto-electroluminescence (MEL) of a thermally activated delayed fluorescence (TADF)-emitter-based OLED, which in reference devices have shown an MEL of about 60% for magnetic fields on the order of 10 mT. Maximum sensitivity of about 0.15 nA/mT (150 μV/mT or 15 mV/kG with amplification) is achieved at a magnetic field of 3–4 mT. While the detectivity is limited to ∼10 –3 T·Hz –1/2, we show this can be improved upon as the magnetic field detection sensitivity of OLEDs measured by an external Si-detector is about an order of magnitude higher. Sensitivity of 2 nA/mT and detectivities better than 10 –5 T·Hz –1/2 are demonstrated, and the intrinsic detectivity limit is estimated to be on the order of 10 –9 T·Hz –1/2 .