Chiral-induced spin selectivity enables a room-temperature spin light-emitting diode

Abstract

In traditional optoelectronic approaches, control over spin, charge, and light requires the use of both electrical and magnetic fields. In a spin-polarized light-emitting diode (spin-LED), charges are injected, and circularly polarized light is emitted from spin-polarized carrier pairs. Typically, the injection of carriers occurs with the application of an electric field, whereas spin polarization can be achieved using an applied magnetic field or polarized ferromagnetic contacts. We used chiral-induced spin selectivity (CISS) to produce spin-polarized carriers and demonstrate a spin-LED that operates at room temperature without magnetic fields or ferromagnetic contacts. The CISS layer consists of oriented, self-assembled small chiral molecules within a layered organic-inorganic metal-halide hybrid semiconductor framework. The spin-LED achieves ±2.6% circularly polarized electroluminescence at room temperature.

Great Amplification of Circular Polarization Sensitivity via Heterostructure Engineering of a Chiral Two-Dimensional Hybrid Perovskite Crystal with a Three-Dimensional MAPbI3 Crystal

“…According to the recent mCP-AFM and MR studies, this chirality transfer is expected to originate from the selective spin-polarized carrier transport between chiral 2D perovskites and 3D perovskite. 30 , 37 , 53 − 55 The selective spin-polarized carrier transport is the manifestation of a chiral-induced spin selectivity (CISS) effect which occurs when chiral cations of chiral perovskites only allow the one of the spin states (up-spin or down-spin state) to transport through the organic spacer while blocking the other one. Under CPL illumination, photogenerated carriers in [( R )-MPA] 2 PbCl 4 are highly spin-polarized in which the spin orientation is determined by the R -MPA cation.…”

“…In this way, the built-in electric field can efficiently separate/transport those spin-polarized excitons with particular spin orientation, which reduces their recombination rate and results in pronounced I SC R . 37 Thus, the circular polarization sensitivity can be greatly amplified. On the basis of the above results, we conclude that the chirality in the single-phase chiral hybrid perovskite can be transferred to the heterostructure, and the spin-selective interfacial charge transfer results in the amplification of circular polarization sensitivity.…”

The Importance of Spin State in Chiral Supramolecular Electronics

“…The sign of the magnetization studied by Magneto-optic Kerr rotation effect depended on the chirality of the HOIP ( Huang et al, 2020 ). Recently, a spin-polarized LED at room temperature without magnetic or ferromagnetic contacts, which are normally required has been reported ( Kim et al, 2021 ). Furthermore, bioinspired chiral metal-organic Cu(II) phenylalanine (D- or L-) crystals have shown to present CISS electron conduction over long ranges (300 nm) at room temperature measured by magnetic cp-AFM.…”

Imide-Functionalized Helical PAHs: A Step towards New Chiral Functional Materials

“…This geometry allows for pronounced chirality effects, such as high values of optical rotation (OR), circular dichroism (CD), and CP luminescence (CPL). 15 This has led to increasing focus on helical chiral organic molecules for applications such as chiroptical switches, 16 chirality-dependent organization, organic light-emitting diodes (OLEDs) emitting circularly polarized light (spin-LEDs), 17 CP-responsive organic field-effect transistors [18][19][20] (OFETs), and in stereoselective synthesis 21 which have been detailed in multiple reviews. Still, their chiroptical properties leave much to be desired.…”