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.

Transient and CW spectroscopies unravel giant Rashba splitting in 2D hybrid perovskite multilayers.

Magnetic field e ects have been a successful tool for studying carrier dynamics in organic semiconductors as the weak spin-orbit coupling in these materials gives rise to long spin relaxation times. As the spin-orbit coupling is strong in organic-inorganic hybrid perovskites, which are promising materials for photovoltaic and light-emitting applications, magnetic field e ects are expected to be negligible in these optoelectronic devices. We measured significant magneto-photocurrent, magneto-electroluminescence and magneto-photoluminescence responses in hybrid perovskite devices and thin films, where the amplitude and shape are correlated to each other through the electron-hole lifetime, which depends on the perovskite film morphology. We attribute these responses to magnetic-field-induced spin-mixing of the photogenerated electron-hole pairs with di erent g-factors-the g model. We validate this model by measuring large g (∼ 0.65) using field-induced circularly polarized photoluminescence, and electron-hole pair lifetime using picosecond pump-probe spectroscopy.T he organic-inorganic hybrid perovskites (CH 3 NH 3 PbX 3 , X = halogen; Fig. 1a) have attracted an immense interest recently as an excellent candidate for photovoltaic solar cells 1-7 . Record power conversion efficiency (PCE) of 19.3% has been achieved in optimized devices with a finely grown perovskite active layer 8 . It has been shown that the perovskites have a large absorption coefficient in the visible-near-infrared spectral range, and high charge carriers' photogeneration efficiency 9-11 ; both properties are excellent for photovoltaic applications. Interestingly, the same hybrid perovskites show photoluminescence (PL) emission ( Fig. 1b), laser action 12 and electroluminescence (EL) in lightemitting diodes 13 (LEDs). However, the underlying photophysics of the efficient charge photogeneration for photovoltaic applications, and the mechanism of radiative charge recombination that is required for LED applications are not yet clear 14,15 . In particular the perovskite layer consists of many tiny crystalline domains, where the natural disorder may encourage the formation of relatively long-lived spin-1/2 electron-hole (e-h) pairs 16 . Consequently, the generation and recombination of these spin-pair species may be influenced by a magnetic field.The magnetic field effect (MFE) technique has been a powerful tool for studying spin-dependent generation and recombination processes of spin-pair species in carbon-based semiconductor film devices 17,18 . In this technique the applied magnetic field, B, modulates the outcome physical quantity in the optoelectronic device, in the form of magneto-conductivity (MC) and magnetophotoconductivity (MPC) in organic photovoltaic cells 19 , magnetoelectroluminescence (MEL) in organic LEDs (ref. 20), and magnetophotoluminescence (MPL) in pristine films 21 . This occurs because B changes the spin sublevels character in the spin-pair manifold; which, in turn changes the inter-sublevels spin-mixing rates that consequently ...

Recently the hybrid organic-inorganic trihalide perovskites have shown remarkable performance as active layers in photovoltaic and other optoelectronic devices. However, their spin characteristic properties have not been fully studied, although due to the relatively large spin-orbit coupling these materials may show great promise for spintronic applications. Here we demonstrate spin-polarized carrier injection into methylammonium lead bromide films from metallic ferromagnetic electrodes in two spintronic-based devices: a ‘spin light emitting diode’ that results in circularly polarized electroluminescence emission; and a ‘vertical spin valve’ that shows giant magnetoresistance. In addition, we also apply a magnetic field perpendicular to the injected spins orientation for measuring the ‘Hanle effect’, from which we obtain a relatively long spin lifetime for the electrically injected carriers. Our measurements initiate the field of hybrid perovskites spin-related optoelectronic applications.

We report the charge carrier recombination rate and spin coherence lifetimes in single crystals of two-dimensional (2D) Ruddlesden−Popper perovskites PEA 2 PbI 4 •(MAPbI 3 ) n−1 (PEA, phenethylammonium; MA, methylammonium; n = 1, 2, 3, 4). Layer thickness-dependent charge carrier recombination rates are observed, with the fastest rates for n = 1 because of the large exciton binding energy, and the slowest rates are observed for n = 2. Room-temperature spin coherence times also show a nonmonotonic layer thickness dependence with an increasing spin coherence lifetime with increasing layer thickness from n = 1 to n = 4, followed by a decrease in lifetime from n = 4 to ∞. The longest coherence lifetime of ∼7 ps is observed in the n = 4 sample. Our results are consistent with two contributions: Rashba splitting increases the spin coherence lifetime going from the n = ∞ to the layered systems, while phonon scattering, which increases for smaller layers, decreases the spin coherence lifetime. The interplay between these two factors contributes to the layer thickness dependence.