Room-temperature solution-processed spin organic light-emitting diodes based on chiral 2D halide perovskites†

Chiral R-/S-methylbenzylamine (R-/S-MBA) was used as a cation to form chiral 2D perovskites with different stoichiometric ratios 〈n〉 and halide compositions. The chiroptical properties of chiral perovskites, as well as their application in chiral spintronics, were investigated. The chemical composition and chiroptical properties of these materials were investigated by X-ray diffraction, circular dichroism (CD), magnetic CD (MCD), circularly polarized luminescence (CPL) and magnetic CPL (MCPL). Large Stokes shifts were observed when the halide composition of perovskite films with 〈n〉 = 1 was changed from iodide-rich to bromide-rich. Furthermore, circularly polarized electroluminescence was observed at room temperature in the absence of an external magnetic field. The degree of spin current polarization of 2D chiral perovskites reached 86%. In terms of spintronic device applications, spin organic light-emitting diodes were realized by using chiral 2D perovskite films with different halide compositions as spin filters and using a polymer called Super Yellow as the emissive layer. The halide composition of the spin filter does not affect the emission wavelength of the device. A maximum g_CP–EL of 1 × 10⁻² was obtained. The chiroptical properties of chiral halide perovskites demonstrated in this work are useful for chiroptoelectronics and chiral spintronics.