Chiral Halide Perovskite Materials for Optoelectronic and Spintronic Devices – ChiroSpin

For more than 15 years, Halide Perovskites (HPs) have been an important class of materials in the fields of photovoltaic and photoluminescence. Chiral HPs, the first examples of which have been recently reported, bring new perspectives for chiroptical applications, such as circularly polarized luminescence (CPL), and spintronic applications. For example, the emergent field of chiro-spintronics proposes to use chiral molecules as a substitute for ferromagnetic materials thanks to the spin-specific interaction between electrons and chiral molecules, a phenomenon called CISS, “chiral-induced spin selectivity”. The project aims to reveal the potential of chiral HP materials for CPL and chiro-spintronics. In 2017, two breakthroughs in the research area of HPs have been achieved and are the foundations of the present project: first, the discovery of the d-HPs, a family of 3D HPs wherein defects are created by replacing part of the metal-halogen sites by organic cations; second, the first study of chirality-related properties of chiral HPs. After insertion of chiral organic cations in low-dimensional HPs (2D and 1D networks), the resulting materials have shown very promising applications for CPL and spintronics. Still, CPL emitters based on HPs are very few, spintronic devices mainly consist in CPL detectors, and chiral 3D HPs couldn’t be obtained due to a size constraint for insertion of the cation in the cubic cavities of 3D HPs.
Thanks to the presence of defects in the new family of 3D d-HPs, insertion of large chiral cations can be envisaged for the preparation of chiral 3D HPs. Preliminary results obtained by the scientific coordinator of the project (CPL of bulk crystals of the first 3D chiral HPs, a new series of 2D compounds promising for CISS effect study) strengthen the objectives of fabricating new optoelectronic and spintronic devices such as CP-PeLEDs and spin-LEDs. Synthesis of more chiral organic molecules will also allow to prepare a variety of 3D, 2D and 1D networks. This will not only allow us to create materials and devices with outstanding properties but also contribute to reveal the fundamental origins of the CISS effect, whose performances still need to be theoretically explained.
Therefore, with the characterization of chiral HP materials with controlled dimensionality and bulk symmetry, ChiroSpin aims to provide a unique combined chemical and physical systematic study of spin-polarized effects and chirality degree in HP materials and devices. Precisely, ChiroSpin will deliver:
(1) chiral HP compounds with controlled dimensionality (3D, 2D and 1D), crystal symmetry (two-fold, three-fold and four-fold) and chemical composition (new chiral organic cations, easily modulable metal-halide inorganic part);
(2) chiral HP bulk crystals and thin films showing CPL and/or CISS effect; important information for the factors influencing CPL and for the theory of the CISS effect;
(3) optoelectronic (such as the first CP-PeLED) and chiro-spintronic devices (such as spin-LEDs) based on chiral HP materials; insights into the transfer of the CISS effect to practical spintronics.