Blue Circularly Polarized Luminescence from Quantum-Confined CsPbBr₃ Nanocrystals with a Different Degree of Shape Anisotropy

Abstract

Circularly polarized luminescence is an attractive characteristic of chiral perovskite nanocrystals, as it opens possibilities for applications such as spin-polarized light-emitting diodes and chiral light-selective photodetectors. While previous research has mainly focused on green- and red-emitting chiral perovskite nanocrystals, the exploration of blue-emitting counterparts with efficient circularly polarized luminescence activity is still in its early stages. Here, we synthesize nanocubes, nanoribbons, and nanowires of CsPbBr3 perovskites, which exhibited strong blue emission thanks to quantum confinement in at least two dimensions. Their chiral induction is achieved by attaching chiral molecules (R/S-methylbenzylammonium bromide) to the surface of nanocrystals, resulting in circular dichroism and circularly polarized luminescence. Upon attachment of chiral ligands, the average absorption dissymmetry factor, |gabs|, reached 9 × 10–5 for nanocubes, 1.5 × 10–4 for nanoribbons, and 2.9 × 10–4 for nanowires, thus clearly revealing shape-dependence. Moreover, we achieved blue circular polarized luminescence for all three kinds of samples, with the average luminescence dissymmetry factor, |glum|, of 1.4 × 10–4, 4 × 10–4, and 5.2 × 10–4 for nanocubes, nanoribbons, and nanowires, respectively.