Perovskites

Researchers at the Institute of Chemistry and the Center for Nanoscience and Nanotechnology at the Hebrew University of Jerusalem, led by Dr. Joanna Dehnel and Dr. Igal Levine, have introduced a contactless technique for probing how chiral 2D perovskites respond differently to circularly polarized light, without first building the material into a complete electronic device.

Chiral perovskites exist in two mirror-image forms, much like a left and right hand, and are of growing interest for spintronics and optoelectronics because their crystal structure can couple light polarization, electrical charge and electron spin without requiring an external magnetic field. Studying that coupling has traditionally meant fabricating a full device with metal contacts, a step that can introduce defects and other artifacts that obscure the material's intrinsic electronic response. To get around this, the team developed circularly polarized time-resolved surface photovoltage (CP-TRSPV), a technique that tracks how electrical charges separate inside the material under circularly polarized illumination, without a top electrical contact. The method can follow the resulting signal over an unusually wide time window, from nanoseconds to milliseconds.

Researchers from the University of Nevada Las Vegas, Lawrence Berkeley National Laboratory, International Kazakh-Turkish University, University of California and Argonne National Laboratory have introduced a predictive synthesis framework to boost the spin-relevant performance of chiral 2D metal halide perovskites (MHPs) for next-generation spintronics. Chiral 2D MHPs are promising materials for spin-optoelectronic devices that exploit the electron’s spin degree of freedom, yet their chiroptical response, quantified by the absorption dissymmetry factor (g_abs), has shown large variability and poor reproducibility. This has hindered the rational design of reliable spintronic components such as circularly polarized LEDs, photodetectors, and spin filters.

To tackle this challenge, the team built a data-driven framework that directly links synthesis “knobs” to chiroptical properties. Using Pearson’s correlation, ANOVA, and Gaussian process regression, they systematically evaluated how solvent choice, annealing temperature, film thickness, and other structural and morphological factors influence g_abs. The analysis reveals solvent choice as the primary driver of variability: acetonitrile (ACN)-processed films consistently exhibit higher and more reproducible g_abs values than films fabricated from dimethylformamide (DMF) or ACN:dimethyl sulfoxide (ACN:DMSO) mixtures. For ACN-based films, the model identifies specific annealing temperature and thickness ranges that maximize g_abs, providing a clear processing playbook instead of ad hoc optimization.

A University of North Carolina at Chapel Hill research team has demonstrated a novel way to encode quantum information directly within the light produced by two-dimensional perovskites - opening a potential path to simpler, more efficient quantum communication systems. The study explores how spin dynamics in two-dimensional organic–inorganic hybrid perovskite (2D-OIHP) quantum wells can generate polarization-encoded photons suitable for secure communication protocols.

Two-dimensional perovskites are well known for their performance in light-emitting and photovoltaic devices, but the UNC team, led by Professor Andrew Moran, has shown they can also act as microscopic light sources whose intrinsic exciton spin behavior defines the polarization of emitted photons. When ultrafast laser pulses excite the material, they generate pairs of bound charge carriers - excitons - whose spins determine the polarization of emitted light.

Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center (EFRC), University of Wisconsin-Madison, University of Colorado Boulder, Duke University and University of Utah have discovered a new process to induce chirality in halide perovskite semiconductors, which could open the door to cutting-edge electronic applications.

The development is the latest in a series of advancements made by the team involving the introduction and control of chirality. Chirality refers to a structure that cannot be superimposed on its mirror image, such as a hand, and allows greater control of electrons by directing their spin. The researchers have been able to create a spin-polarized LED using chiral perovskite semiconductor in the absence of extremely low temperatures and a magnetic field, as was previously reported. The newest advance accelerates the materials development process for spin control.

In a recent sturdy, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Northern Illinois University discovered that they could use light to detect the spin state in a class of materials called perovskites (specifically in this research methylammonium lead iodide, or MAPbI₃). 

To understand spin, consider electrons orbiting the atomic nucleus. When atoms are close together, they can share some of their outer electrons, which creates a bond between them. Each bond contains two electrons that are ​“paired,” meaning they share an orbital — the region where they move. Now, each of these paired electrons has one of two possible spin states: spin up or spin down. If one electron is spin up, the other is spin down. Since we can’t know exactly which electron has which spin without looking at them, we say they exist in a quantum superposition — a state where they are both spin up and spin down until observed.

Researchers from Cambridge University in the UK, Korea's DGIST and Harvard University in the U.S have shown that electron spins could become more efficient and easier to manage through a light-based approach using halide perovskite semiconductors. The team observed ultrafast spin-domain formation in polycrystalline halide perovskite thin films in response to irradiating the films with circularly polarized light at room temperature.

Photoinduced spin-charge interconversion in semiconductors, with spin-orbit coupling, could provide a route to spintronics that does not require external magnetic fields, which tend to be challenging to control. An electron can have two spin states, up or down, and these states can be used to store and process information. But manipulating spin states can be tricky, requiring the use of magnetic fields on perfectly ordered materials at extremely low temperatures to work.

A team of researchers at MIT, Complutense University of Madrid and the University of Pavia has designed a perovskite-based device that combines aspects of electronics and photonics, that could lead to new kinds of computer chips or quantum qubits.

The new work involved sandwiching tiny flakes of a perovskite material in between two precisely spaced reflective surfaces. By creating these perovskite sandwiches and stimulating them with laser beams, the researchers were able to directly control the momentum of certain “quasiparticles” within the system. Known as exciton-polariton pairs, these quasiparticles are hybrids of light and matter. Being able to control this property could ultimately make it possible to read and write data to devices based on this phenomenon.

Scientists from the University of Warsaw, Poland-based Military University of Technology, CNR Nanotec, the University of Southampton and the University of Iceland have designed a new photonic system with electrically tuned topological features, constructed of perovskites and liquid crystals. The new system can be used to create efficient light sources.

Perovskites are highly-studied materials that have the potential to revolutionize the solar energy fields, among others. These are durable and easy-to-produce materials, the special property of which is a high solar light absorption coefficient and they are therefore used to develop new, more efficient photovoltaic cells. In recent years, the emission properties of these materials, so far underestimated, have been used.

A team of researchers from the National Renewable Energy Laboratory (NREL) and the University of Utah has developed a new type of LEDs that utilizes spintronics without needing a magnetic field, magnetic materials or cryogenic temperatures.

“The companies that make LEDs or TV and computer displays don’t want to deal with magnetic fields and magnetic materials. It’s heavy and expensive to do it,” said Valy Vardeny, distinguished professor of physics and astronomy at the University of Utah. “Here, chiral molecules are self-assembled into standing arrays, like soldiers, that actively spin polarize the injected electrons, which subsequently lead to circularly polarized light emission. With no magnetic field, expensive ferromagnets and with no need for extremely low temperatures. Those are no-nos for the industry.”

Researchers from the NREL and the University of Utah have demonstrated how electron transport with a particular spin state through a two-dimensional hybrid organic-inorganic perovskite can be manipulated by introducing special organic molecules in the multilayer structure.

One way to control spin-polarized currents is through "chiral-induced" spin selectivity where the transport of electrons depends upon the transporting materials’ chirality—a structural property of a system where its mirror image is not superimposable on itself. The scientists have demonstrated how to integrate a chiral organic sublattice into an inorganic framework, creating a chiral system that can transport electrons with the desired spin control. In such systems, the chiral perovskite films act as a spin filter.