Solution-processed polarized light-emitting diodes

Polarized light sources play a significant role in a growing number of applications: from general illumination to highly efficient displays. Solution-processed polarized light-emitting diodes (pol-LEDs) have attracted remarkable interest because of the wide choice of emissive materials, capability to be solution-processed and easy fabrication. We first classify organic pol-LEDs into two categories according to their aligning techniques, including (1) alignment without an oriented substrate and (2) alignment on an oriented substrate. Recent progress in aligning techniques, emissive materials, substrate materials, device performances and polarizing properties is summarized. We also discuss pol-LEDs based on emissive materials of one-dimensional (1D) II-VI and lead halide perovskite nanomaterials. Finally, an outlook is provided on research trends in the development of solution-processed pol-LEDs.