Core–Shell Perovskite Quantum Dots for Highly Selective Room‐Temperature Spin Light‐Emitting Diodes

• Published in: Advanced materials (Weinheim) 2024-02, Vol.36 (5), p.e2309335-n/a
• Main Authors: Jang, Gyumin, Jo, Dae‐Yeon, Ma, Sunihl, Lee, Junwoo, Son, Jaehyun, Lee, Chan Uk, Jeong, Wooyong, Yang, Seongyeon, Park, Jeong Hyun, Yang, Heesun, Moon, Jooho
• Format: Article
• Language: English
• Subjects: Cations; chiral‐induced spin selectivity; Circular polarization; core–shell; Current carriers; Emitters; Inkjet printing; Light emitting diodes; Light sources; Magnetic recording; nanocrystals; perovskite; Perovskites; Photoluminescence; Polarization (spin alignment); Polarized light; Quantum dots; Quantum efficiency; Room temperature; spin‐LEDs; Two dimensional analysis
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202309335

Circularly polarized light (CPL) is a crucial light source with a wide variety of potential applications such as magnetic recording, and 3D display. Here, core–shell heterostructured perovskite quantum dots (QDs) for room‐temperature spin‐polarized light‐emitting diodes (spin‐LEDs) are developed. Specifically, a 2D chiral perovskite shell is deposited onto the achiral 3D inorganic perovskite (CsPbBr3) core. Owing to the chiral‐induced spin selectivity effect, the spin state of the injected charge carriers is biased when they are transmitted through the 2D chiral shell. The spin‐controlled carriers then radiatively recombine inside the CsPbBr3 emissive core, resulting in CPL emission. It is demonstrated that the (R)‐ and (S)‐1‐(2‐(naphthyl)ethylamine) (R‐/S‐NEA) 2D chiral cations enhance the spin polarization degree due to their strong chiroptical properties. Systematical defect analyses confirm that 2D chiral cations (i.e., R‐/S‐NEA) successfully passivate halide vacancies at the surface of the CsPbBr3 QDs, thereby attaining a high photoluminescence quantum yield of 78%. Moreover, the spin‐LEDs prepared with core–shell QDs achieve a maximum external quantum efficiency of 5.47% and circularly polarized electroluminescence with a polarization degree (PCP‐EL) of 12% at room temperature. Finally, various patterns fabricated by inkjet printing the core–shell QDs emit strong CPL, highlighting their potential as an emitter for next‐generation displays. Core–shell structured perovskite quantum dots with outstanding spin polarization property are developed for room‐temperature spin‐polarized light‐emitting diodes. The 2D chiral organic cation in the shell passivates defects on the quantum dot surface, thereby yielding a high external quantum efficiency of 5.47% and strong circularly polarized electroluminescence with a dissymmetry factor |gCP‐EL| of 2.4 × 10−1.