Mechanically Tuneable Circularly Polarized Flexible Spin Light Emitting Diodes

Abstract

Flexible spintronics is a crucial emerging field in next-generation wearable and innovative electronic technology. Traditionally, spintronics relies on external magnetic fields and ferromagnetic contacts to achieve spin-polarized carriers. This makes it challenging to realize flexible spin devices due to the inherently bulky and rigid constituent materials. To overcome these drawbacks, a strategy is proposed for fabricating flexible spin light-emitting diodes by integrating self-assembled monolayer (SAM) of P3HT-COOH, chiral metal–organic framework (Chiral-MOF), quantum dots (QDs), and polyethylene terephthalate substrate. The chiral europium-based MOFs employed as a spin-injection layer via the chiral-induced spin selectivity mechanism can effectively polarize the emitting light. The SAM (P3HT-COOH) layer significantly enhances the device stability and light intensity compared to conventional PEDOT: PSS layer-based devices, while the QDs layer serves as the bright emitter. This device achieves an estimated external quantum efficiency (EQE) with a polarization degree (P_CP-EL) of ± 21.86%. Furthermore, P_CP-EL changes (21.86, 20.34, 19.34, 17.45, 17.18, 14.99, 13.54) with stable emission under various bending radii. This approach enables circularly polarized luminescence (CPL) and a tuneable degree of polarization simultaneously, which is free from external magnetic fields or ferromagnetic contacts. The obtained result offers a promising alternative in the field of flexible spintronics and builds up an additional manner to manipulate the physical properties of spin devices.