From 0 to N: circularly polarized luminescence generation from achiral luminophores in fibrous morphologies

Circularly polarized luminescence (CPL) has attracted broad interest due to its potential applications in advanced photonics and electronics. CPL is generally produced from chiral moiety-decorated pi-conjugated molecules. Alternatively, CPL can be directly generated from achiral luminescent materials in helical and twisted supramolecular systems, which circumvents the tough and tedious syntheses in traditional methods. In particular, one-dimensional helical supramolecular systems in the fibrous morphology are superior for CPL generation over those in spheroidal or planar structures, because of their high dissymmetry factors (g(lum)). Efforts on one side are focused on the development of helical luminescent fibers with high g(lum), and on the other side, are directed toward the arrangement of nanofibers to produce scalable materials (films or fibers) with chiral activity. This review summarizes the recent advances in CPL generation from supramolecular systems, illustrating how the chirality transfer, amplification, and regulation of CPL are achieved in fibrous morphologies. Their working mechanisms at hierarchical length scales, including helical fibrous supramolecular assemblies at the nanoscale, chiral films constructed using helically arranged nanofibers at the microscale, and macroscopic fibers via mechanical twisting, are described sequentially. Finally, the current challenges and future opportunities of the chiral systems are also presented.