Organic semiconductors and organic–inorganic hybrids are promising materials for spintronic‐based memory devices. Recently, an alternative route to organic spintronic based on chiral‐induced spin selectivity (CISS) is suggested. In the CISS effect, the chirality of the molecular system itself acts as a spin filter, thus avoiding the use of magnets for spin injection. Here, spin filtering in excess of 85% in helical π‐conjugated materials based on supramolecular nanofibers at room temperature is reported. The high spin‐filtering efficiency can even be observed in nanofibers assembled from mixtures of chiral and achiral molecules through chiral amplification effect. Furthermore and most excitingly, it is shown that both “up” and “down” orientations of filtered spins can be obtained in a single enantiopure system via the temperature‐dependent helicity (P and M) inversion of supramolecular nanofibers. The findings showcase that materials based on helical noncovalently assembled systems are modular platforms with an emerging structure–property relationship for spintronic applications.

Lead-free double perovskite nanocrystals (NCs) of Cs2AgIn1–x Bi x Cl6 (x = 0, 0.05, 0.15, 0.3, 0.6, and 1) were synthesized with control over the size distribution. Detailed structural studies were carried out on the resulting double perovskite NCs to confirm the alloying and structural modification. Alloying of Bi leads to change in optical properties, such as the band gap, and enhancement in oscillator strength of first excitonic transition and the white light emission (WLE) properties. The band gap of the double perovskite NCs was estimated; a direct band gap transition value of ∼3.46 eV is obtained for pure Cs2AgInCl6 NCs. This value of the band gap has reduced with increase of Bi doping, which also leads a band gap transition from direct to indirect band gap. This system exhibits a sub-band gap emission between ∼570 and 620 nm along with band-edge emission, which is strongly dependent on the alloying concentration. A gamut of emission is observed in the alloyed systems. The Commission International de I’Eclairage (CIE) coordinates of (0.36, 0.35) for the 30% Bi-doped sample, with color rendering index values of ∼91, and correlated color temperature of 4443 with D uv of −0.0065 are observed, which are found to be very promising for WLE applications.

The effect of spin polarization in conduction and in electric field-induced polarization was measured for double-stranded DNA oligonucleotides and oligopeptides of different lengths. These measurements were conducted using magnetic contact AFM, spin-dependent electrochemistry, spin-dependent polarization, and magnetoresistance studies. It was established that the spin-dependent conduction through chiral molecules depends on the voltage applied with a power of d, when d is larger than unity, and that there is a different voltage threshold for conducting each of the spin polarizations. In addition, there is no spin flipping during the conduction through the chiral system. The spin polarization depends linearly on the length, within the range of lengths studied, and it seems to scale like the optical activity. These results suggest the importance of the electric polarizability in the chiral-induced spin selectivity process. It was also shown that the preferred spin back scattering is suppressed, compared with the nonpreferred spin, probably as a result of the coupling between the electron's linear momentum and its spin as a result of the chiral potential.

The theoretical explanation for the chiral-induced spin selectivity effect, in which electrons’ passage through a chiral system depends on their spin and the handedness of the system, remains incomplete. Although most experimental work was performed at room temperature, most of the proposed theories did not include vibrations. Here, we present temperature-dependent experiments and a theoretical model that captures all observations and provides spin polarization values that are consistent with the experimental results. The model includes the vibrational contribution to the spin orbit coupling. It highlights the importance of dissipation and the relation between the effect and the optical activity. The model explains the main features related to the chiral-induced spin selectivity effect and provides a new framework for future calculations and experiments.

In past studies, spin selective transport was observed in polymers and supramolecular structures that are based on homochiral building blocks possessing stereocenters. Here we address the question to what extent chiral building blocks are required for observing the chiral induced spin selectivity (CISS) effect. We demonstrate the CISS effect in supramolecular polymers exclusively containing achiral monomers, where the supramolecular chirality was induced by chiral solvents that were removed from the fibers before measuring. Spin-selective transport was observed for electrons transmitted perpendicular to the fibers' long axis. The spin polarization correlates with the intensity of the CD spectra of the polymers, indicating that the effect is nonlocal. It is found that the spin polarization increases with the samples' thickness and the thickness dependence is the result of at least two mechanisms: the first is the CISS effect, and the second reduces the spin polarization due to scattering. Temperature dependence studies provide the first support for theoretical work that suggested that phonons may contribute to the spin polarization.