Magnetic Field Sensor Based on a OLED/Organic Photodetector Stack

In this study, an all-organic magnetic field sensor basedon anorganic light-emitting diode (OLED) and organic photodetector (OPD)layer stack is presented. This sensor opens possibilities to createprintable, flexible magnetic field sensors using commercially viablecomponents, allowing magnetic field sensors to be simply integratedinto the existing OLED technology. The sensor function is driven bythe large magneto-electroluminescence (MEL) of a thermally activateddelayed fluorescence (TADF)-emitter-based OLED, which in referencedevices have shown an MEL of about 60% for magnetic fields on theorder of 10 mT. Maximum sensitivity of about 0.15 nA/mT (150 & mu;V/mTor 15 mV/kG with amplification) is achieved at a magnetic field of3-4 mT. While the detectivity is limited to & SIM;10(-3) T & BULL;Hz(-1/2), we show this canbe improved upon as the magnetic field detection sensitivity of OLEDsmeasured by an external Si-detector is about an order of magnitudehigher. Sensitivity of 2 nA/mT and detectivities better than 10(-5) T & BULL;Hz (-1/2) are demonstrated,and the intrinsic detectivity limit is estimated to be on the orderof 10(-9) T & BULL;Hz (-1/2).