Mediation of exciton concentration on magnetic field effects in NPB : Alq₃-based heterojunction OLEDs

Organic light-emitting diodes (OLEDs) are considered one of the most promising new display technologies owing to their advantages, such as all-solid-state, high color gamut, and wide viewing angle. However, in terms of special fields, the brightness, lifetime, and stability of the devices need further improvement. Therefore, heterojunction devices with different concentrations were prepared to regulate device brightness. The brightness of the bulk heterojunction device is enhanced by 9740 cd m^-2, with a growth rate of about 26.8%. The impact of various temperatures and various exciton concentrations on the device magneto-conductance (MC) and magneto-electroluminescence (MEL) was investigated. Experimental results demonstrate that the exciton concentration inside the device can be tuned to improve optoelectronic properties and organic magnetic effects. The complex spin mixing process inside the bulk heterojunction device is deeply investigated, which provides a reliable basis for the design of bulk heterojunction devices.