Organic spintronics is an emerging field of nanoscale electronics involving the detection and manipulation of electronic spins in heterostructures that consist of organic and magnetic materials. Compared to conventional inorganic spintronics, organic spintronics offer distinct advantages such as ease of device fabrication and intrinsic low spin scattering rate and high spin coherence over both time and distance. Recently, we have effectively doping nanoparticles in conjugated polymer for optoelectronics application. For example, one of our recent research works involves using magnetic nanoparticles of CoFe as dopants to enhance the quantum efficiency of electroluminance in a single layer organic light emitting device (OLED). The enhancement of quantum efficiency increases with both increasing density of CoFe nanoparticles and external magnetic field. For a given OLED with 0.1 wt % doping, the enhancement of the quantum efficiency reaches ~27% and ~32% without and with a magnetic field, respectively. The origin of these improvements could be attributed to the simultaneous increases of the portion of excitons among total charge carriers and the fraction of singlets among the total excitons. Here is another example, in an attempt to overcome the technical challenges in the conventional solution-processed near infrared (NIR) photodetectors, we have used NaYF4: Yb, Er up-conversion fluorescence nanocrystals to replace the semiconductor quantum dots in conjugated polymers. Under NIR excitation, the NaYF4: Yb, Er nanocrystals emit visible light in the solution-processed NIR photodetectors. The emitted visible light is simultaneously absorbed by the host conjugated polymer to generate photocurrent which indicates that our approach is applicable to fabricate NIR photodetectors while avoiding the major technical challenges associated with semiconductor quantum dots based NIR photodetectors. For spintronics applications, the major technical challenge in organic spintronics devices is to achieve efficient spin injection. We are currently actively working on the following two areas to gain fundamental understanding in organic spintronics.
- Develop novel method to boost the tunneling magnetoresistance (TMR), and the efficiency of spin injection
- Study the mechanism of organic magnetoresistance.
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