Biomimetic non-classical crystallization drives hierarchical structuring of efficient circularly polarized phosphors

Abstract

Hierarchically structured chiral luminescent materials hold promise for achieving efficient circularly polarized luminescence. However, a feasible chemical route to fabricate hierarchically structured chiral luminescent polycrystals is still elusive because of their complex structures and complicated formation process. We here report a biomimetic non-classical crystallization (BNCC) strategy for preparing efficient hierarchically structured chiral luminescent polycrystals using well-designed highly luminescent homochiral copper(I)-iodide hybrid clusters as basic units for non-classical crystallization. By monitoring the crystallization process, we unravel the BNCC mechanism, which involves crystal nucleation, nanoparticles aggregation, oriented attachment, and mesoscopic transformation processes. We finally obtain the circularly polarized phosphors with both high luminescent efficiency of 32% and high luminescent dissymmetry factor of 1.5 × 10−2, achieving the demonstration of a circularly polarized phosphor converted light emitting diode with a polarization degree of 1.84% at room temperature. Our designed BNCC strategy provides a simple, reliable, and large-scale synthetic route for preparing bright circularly polarized phosphors.

Highly soluble copper(i) iodide-based hybrid luminescent semiconductors containing molecular and one-dimensional coordinated anionic inorganic motifs

“…The cationic ligands used in previously reported AIO structures are mostly synthesized by alkylation of a tertiary amine or phosphine group, giving a terminal ammonium or phosphonium cationic centre with sp 3 hybridization. 4,12,17–20,23,25 Here, by substitution on the N atoms of imidazole derivatives, four bidentate cationic ligands with sp 2 hybridized bridging imidazolium were prepared. The molecular structures of the ligands are shown in Fig.…”

“…17–21 The integration of the coordination bonds (from neutral structures) and ionic bonds (from ionic structures) in a single crystal lattice allows the AIO structures to inherit all the beneficial features from the two constituents, such as optical tunability, enhanced chemical and thermal stability, strong luminescence, and solution processability. 4,9,22–24 These desirable features make the AIO-type structures promising candidates for possible use in solution-processed thin-film devices, including eco-friendly lighting phosphors, 18,19,21 emitting layers of LED devices, 4 and luminescent solar concentrators (LSC). 24 On the other hand, an in-depth study and understanding of the structure–property relationships in these materials is equally important and will be crucial in guiding future efforts to further modify their structures and to enhance/optimize their properties.…”

Viewing Aggregation-Induced Emission of Metal Nanoclusters from Design Strategies to Applications

“…CPL NCs can also be prepared for LED devices. For example, a circularly polarized light source was successfully realized based on copper(I)-iodide hybrid clusters [ 95 ]. Highly quantum-efficient (>95%) chiral silver clusters Ag 6 L 6 were prepared into a WLED by combining 465 nm blue LEDs, which emitted nearly identical white emission as commercial lighting systems (blue chips + YAG: Ce 3+ ) [ 15 ].…”

“…Recently, Yao et al worked on a design for highly efficient chiral hybrid copper(I) halides NCs [ 95 , 120 , 121 ]. As shown in Figure 9 a, R/S-Cu 2 I 2 (BINAP) 2 hybrid clusters with a layered conformation were designed and synthesized [ 121 ].…”

“…Further, with the assistance of polyvinylpyrrolidone (PVP), hexagonal flake-like microcrystals with a high g lum (9.5 × 10 −3 ) were obtained in an ethanol solution based on intermolecular interactions ( Figure 9 b). On the basis above, Yao et al synthesized high-performance CPL materials (PLQY: 32%, g lum : 1.5 × 10 −2 ) with the biomimetic non-classical crystallization (BNCC) strategy [ 95 ]. The main crystallization process was revealed, involving nanocrystal nucleation, aggregation, oriented attachment, and mesoscopic transformation ( Figure 9 c).…”