Chiral hybrid halide perovskites offer a unique platform where structural chirality, lattice dynamics, and spin–orbit coupling converge to generate rich optical and spin-dependent phenomena. Their soft lattices and flexible organic–inorganic frameworks allow strong responses to atomic motion, making them ideal for exploring how lattice dynamics influence light–matter and spin interactions.

Using first-principles and machine-learning–accelerated simulations, we investigate the lattice dynamics, optical activity, and spin textures of two-dimensional chiral lead-halide perovskites. We identify vibrational modes with chiral character—chiral phonons—that couple to excitonic and spin states, modulating both circular dichroism and spin polarization. Temperature-dependent structural fluctuations play a key role in tuning these chiroptical and spin-resolved properties. Together, these results provide a microscopic understanding of how chirality manifests across the lattice, optical, and spin degrees of freedom. Building on this foundation, we outline a future direction linking these effects through electron–phonon coupling, offering new perspectives on the dynamic origins of chiral-induced spin selectivity (CISS) in hybrid perovskites.

Solution-processable semiconductors such as halide perovskites and certain molecules are promising for next-generation spin-optoelectronic applications [1]. Yet, we don’t fully understand what mechanisms govern charge, spin and light polarization in such emerging energy materials, and even less how these are affected by chirality [2].

In this talk, I will give an overview of our recent efforts to understand the spin-optoelectronic performance of these materials through time-, space- and polarization-resolved spectroscopy and microscopy, and how these insights may enhance the performance of solar cells and other energy conversion applications.

For investigating halide perovskite films, we pushed broadband circular dichroism to diffraction-limited spatial and 15 fs time resolution for creating a spin cinematography technique to witness the ultrafast formation of spin domains due to local symmetry breaking and spin-momentum locking [3].

I will then introduce our most recent development of a transient sensitive broadband full Stokes-vector spectroscopy with unprecedented time- and polarization resolution to track the emergence of chiral light emission [4].

To conclude, I will apply some of the above tools to the study of new halide perovskite materials [5].

[1] Nature Reviews Materials 8, 365 (2023).

[2] Nature Reviews Chemistry 9, 208 (2025).

[3] Nature Materials 22, 977 (2023).

[4] Nature 643, 675 (2025).

[5] Unpublished (2026).

Low-dimensional perovskites (LDPs), composed of single or few inorganic octahedral layers separated by bulky organic cations, have emerged as a promising class of semiconductors combining superior environmental stability with highly tunable electronic properties. While their incorporation as passivation layers has significantly improved the performance and durability of three-dimensional (3D) perovskite solar cells, their broader potential as functional materials for photovoltaic applications remains largely unexplored. Recent advances revealing ferroelectric behavior, symmetry-driven phenomena, and controllable crystal orientation have opened new opportunities to exploit LDPs beyond their conventional role as interfacial stabilizers.

In this contribution, we present recent progress in the development of functional low-dimensional perovskites for next-generation solar cells. We first demonstrate how ferroelectric layered perovskites can be engineered at critical interfaces to promote directional charge separation and extraction. The intrinsic polarization of these materials generates local electric fields that facilitate carrier transport, suppress interfacial recombination, and improve device operational stability. We further discuss emerging approaches based on molecular design, including chiral organic spacers, to tailor interfacial charge-transfer processes and electronic interactions in layered perovskite heterostructures.

Beyond interface engineering, we address one of the key limitations hindering the direct implementation of LDPs as photoactive absorbers: inefficient out-of-plane charge transport. Conventional layered perovskites typically exhibit randomly oriented inorganic frameworks, creating energetic and structural barriers for vertical carrier extraction. To overcome this challenge, we develop a crystallographic engineering strategy that promotes preferential vertical alignment of the inorganic layers, establishing efficient charge-percolation pathways while preserving the intrinsic stability advantages of low-dimensional structures.

This approach enables a substantial enhancement in carrier transport and photovoltaic performance, leading to a record power conversion efficiency of 9.4% together with an open-circuit voltage approaching 1.4 V, among the highest values reported for low-dimensional perovskite solar cells. Advanced structural, spectroscopic, and optoelectronic investigations reveal a direct correlation between crystalline orientation, polarization effects, and charge-transport dynamics, providing fundamental insights into the mechanisms governing device operation.

Collectively, these results establish low-dimensional perovskites as a versatile platform for photovoltaic innovation. By combining ferroelectric functionality, rational molecular design, and controlled crystal growth, we introduce new strategies to manipulate charge generation, separation, and transport in layered semiconductors. These findings pave the way toward efficient and intrinsically stable photovoltaic technologies for emerging applications ranging from indoor energy harvesting and tandem solar cells to building-integrated photovoltaics and agrivoltaic systems.

OLEDs typically have active layer thicknesses below 200 nm. This makes the incorporation of photonic structures within the device architecture challenging as these structures are generally thicker than 200 nm. Solution processed polymer based LEDs and vacuum deposited multilayer organic LEDs, have different advantages and challenges with respect to the incorporation of nanophotonic structures.

We will report on different strategies to incorporate nanophotonic structures in OLEDs with the aim to obtain circularly polarized electroluminescence. The nanophotonic structures are prepared using a PDMS stamp on large areas.[3] These nanophotonic structures are modified with a thin transparent conductive oxide using pulsed laser deposition. The enables there use as nanophotonic substrates for the preparation of OLEDs. For the OLEDs, both solvent processed polymer based emitters and vacuum sublimed phosphorescent emitters are evaluated. As an alternative approach, top emitting OLEDs are prepared on which the nanophotonic structures are applied. In both these approaches we observe circularly polarized light under electrical excitation. The maximum values we observed are gEL = 0.2  as a result of the excellent compatibility of the nanophotonic nanostructures and the vacuum sublimated fabrication of OLEDs.

References:

1. M. Forzatti, et al., Organic Light-Emitting Diodes Comprising an Undoped Thermally Activated Delayed Fluorescence Emissive Layer and a Thick Inorganic Perovskite Hole Transport Layer. ACS Photonics. 11, 4151-4160 (2024)

2. Mendoza-Carreño, J. et al. A single nanophotonic platform for producing circularly polarized white light from non-chiral emitters. Nat. Commun. 15, 10443 (2024).

National Center for Scientific Research DemokritosNational Center for Scientific Research DemokritosNational Center for Scientific Research DemokritosNational Center for Scientific Research Demokritos

Conjugated chiral materials can emit circularly-polarised (CP) light within thin films and optoelectronic devices. CP-light is relevant to a range of technologies, including displays, optical communication, and emerging quantum information. Chiral light-emitting polymers have gained increasing attention due to their capability to combine strong chiroptical responses with the optoelectronic characteristics typical of organic conjugated materials, making them attractive for circularly polarised organic light-emitting diodes (CP-OLEDs).

Although circularly polarised electroluminescence can be achieved from intrinsically chiral organic chromophores, chiral polymers and polymer-based thin films can overcome several intrinsic limitations of small molecules: the magnitude of the chiroptical response can be amplified to achieve dissymmetry factors that are unusually large for organic emitters. Blending chiral additives, such as aza[6]-helicene, into conjugated polymer thin films has proven to be an effective route to high-performance CP-OLEDs, enabling high efficiencies alongside strong CP-light emission. Notably, device studies revealed behaviours that could not be explained by treating the emissive layer as a conventional chiral emitter.^[1]

This talk will give an overview of how charge mobility and charge carrier flow direction have a crucial role in controlling the magnitude and sign of CP-light, together with the role of the chiral additive. We will demonstrate how manipulating and managing the flow of charge carriers allows for the electrical control of CP-Light emission properties in a chiral light-emitting polymer, achieved without changing the intrinsic chirality of the film or the employed device architecture. This approach offers a route toward CP-OLEDs where polarisation characteristics can be tuned and optimised through device-relevant parameters and not solely relying on the chemical design of the emitters.^[2] In a complementary direction, this talk will also showcase the potential of energy transfer mechanisms from a chiral polymer host to amplify the dissymmetry of conventional chiral emitters. These concepts will be discussed together with their application to CP-OLEDs,^[3] and their extension to address the limitations of small molecule CP-light emitters in the red region of the visible spectrum.

Cellulose nanocrystals (CNCs) are promising renewable building blocks for chiral optoelectronic materials because of their outstanding thermomechanical properties and their ability to self-assemble into cholesteric liquid-crystalline phases [1]. This chiral organization can be retained in solid films through evaporation-induced self-assembly (EISA), producing photonic structures with characteristic dimensions that interact with UV and visible light. CNCs derived from the cellulose I allomorphs typically possess a right-handed twist along their longitudinal axis and form left-handed cholesteric phases. In contrast, CNCs obtained from cellulose II allomorphs [1, 2] have been reported to display an opposite particle twist and can generate right-handed liquid-crystalline phases, providing opportunities to control the handedness of chiral photonic films. Here, we present our recent work on the preparation, surface modification, and self-assembly of CNC allomorphs obtained from plant and bacterial cellulose sources. In addition to native cellulose I nanocrystals, Mercerization and ethylenediamine treatments were used to produce cellulose II and cellulose III allomorphs [3-5] respectively. The reducing end groups of the nanocrystals were subsequently functionalized with methoxypolyethylene glycol (mPEG) amines. This end-selective modification introduces steric interactions and may generate depletion effects, offering an additional strategy for controlling liquid-crystalline phase behavior without uniformly altering the nanocrystal surface. Using atomic force microscopy (AFM), polarized optical microscopy (POM), and circular dichroism (CD) spectroscopy, we investigate how crystal allomorph, nanocrystal morphology, polymer grafting, surface chemistry, and confinement influence chiral self-assembly and optical response. Our findings demonstrate that the handedness and structural characteristics of CNC-based cholesteric phases can be tuned through such complementary approaches. Polymer-tethered CNC allomorphs [1, 4] therefore provide a versatile bottom-up platform for the development of sustainable chiral photonic and optoelectronic materials, with potential applications in chiral plasmonics [5], optical sensing, and heterogeneous enantioselective catalysis.

Chiral three-dimensional (3D) perovskites exhibit exceptional optoelectronic characteristics and inherent chiroptical activity, which may overcome the limitations of low-dimensional chiral optoelectronic devices and achieve superior performance. The integrated chip of high-performance arbitrary polarized light detection is one of the aims of chiral optoelectronic devices and may be achieved by chiral 3D perovskites. Herein, we first fabricate the wafer-scale integrated full-Stokes polarimeter by the synergy of unprecedented chiral 3D perovskites (R/S-PyEA)Pb2Br6 and one-step capillary-bridge assembly technology. Compared with the chiral low-dimensional perovskites, chiral 3D perovskites present smaller exciton binding energies of 57.3 meV and excellent circular dichroism (CD) absorption properties, yielding excellent circularly polarized light (CPL) photodetectors with an ultrahigh responsivity of 86.7 A W^–1, an unprecedented detectivity exceeding 4.84 × 10¹³ Jones, a high anisotropy factor of 0.42, and high-fidelity CPL imaging with 256 pixels. Moreover, the anisotropic crystal structure also enables chiral 3D perovskites to have a large linear-polarization response with a polarized ratio of 1.52. The combination of linear-polarization and circular-polarization discrimination capabilities guarantees the achievement of a full-Stokes polarimeter. Our study provides new research insights for the large-scale patterning wafer integration of high-performance chiroptical devices.

Halide perovskite nanoparticles have revolutionized the development of optoelectronic devices due to their exceptional photophysical properties. Recently, incorporating chirality into these nanoarchitectures has opened unprecedented horizons by leveraging quantum-level spin control. This breakthrough enables advanced applications, such as the direct emission of circularly polarized light (CPL) in light-emitting diodes (LEDs). However, transitioning these technologies toward a pre-industrial scale demands a rigorous evaluation of their environmental and economic viability under strict sustainability criteria.

This work presents results on the environmental impacts, costs, and toxicity profiles of nanoparticles synthesized through novel procedures designed to improve sustainability within the Safe and Sustainable by Design framework. Building upon this, preliminary sustainability findings for chiral perovskite nanoparticles synthesis are showcased. In other sectors, particularly pharmaceuticals, agrochemicals, and polymers, significant differences have been documented regarding the environmental impacts associated with chiral versus non-chiral materials. Many chiral pesticides and drugs exhibit distinct levels of ecotoxicity and environmental persistence depending on their enantiopurity. Consequently, manufacturing and utilizing a racemate may underestimate or overestimate environmental risks compared to its enantiopure counterpart. Therefore, a fundamental focus of this study is the development of new hazard characterization factors capable of differentiating toxicity profiles between enantiomers, addressing a critical data gap in conventional evaluation platforms.

Furthermore, synthesis and separation processes for chiral compounds to obtain pure enantiomers require additional steps or specialized reagents, which inherently increases their energy and carbon footprints compared to equivalent non-chiral materials. Nevertheless, our findings indicate that this increase is strategically offset by the superior performance of the resulting optoelectronic devices. Notably, direct CPL emission eliminates the need for traditional external optical filters, which typically trap and waste over 50% of light efficiency, thereby optimizing the overall energy performance of the system.

Finally, we introduce a novel methodological approach to analyze the criticality of the specific materials used in these chiral optical devices and compared to conventional ones. This analysis provides an integrated assessment of supply chain vulnerability.

Ultimately, this study defines a holistic matrix that inextricably links advanced device performance with the economic and ecological sustainability of the material cycle.

Organic semiconductors provide a versatile platform for chiral optoelectronics because their optical transitions, excitonic interactions, molecular packing and device operation can all be modified through chemical and processing design. However, many of the most useful organic semiconductors for photodetectors and light-emitting devices are not intrinsically chiral. A central question is therefore how chirality can be introduced into functional organic semiconductors without sacrificing the electronic properties that make them attractive for optoelectronic applications.

In this talk, I will first discuss chirality induction as a general strategy for creating chiroptically active organic semiconductor systems[1]. Rather than relying only on the synthesis of intrinsically chiral chromophores, chiral order can be transferred into functional semiconductor materials through chiral additives, chiral environments, host–guest interactions and controlled thin-film assembly.[2] These approaches allow achiral or weakly chiral organic semiconductors to acquire pronounced circular dichroism, circularly polarized luminescence responses. Importantly, the induced chiroptical activity is not simply a molecular property, but often emerges from collective electronic coupling, excitonic interactions and supramolecular organization in the solid state. This provides a flexible route to incorporate chirality into established organic photodetector and light-emitting diodes .

I will then focus on a more specific consequence of induced electronic chirality: the emergence of chiral orbital texture in organic semiconductor devices. In electrically driven chiral organic films, charge transport can generate orbital polarization when the electronic orbital character is locked to the carrier momentum.[3] This orbital–momentum locking creates a handed electronic texture that is absent in conventional descriptions of molecular circularly polarized luminescence. As a result, the handedness of circularly polarized electroluminescence can become dependent on both the direction of light emission and the direction of current flow, leading to non-reciprocal chiral emission behaviour and unusually large device-level circular polarization.

By connecting chirality induction in functional semiconductor materials with orbital-texture-driven emission in working devices, I will discuss how chiral optoelectronic responses can emerge across different levels of organic semiconductor systems. Rather than being determined solely by molecular stereochemistry, circular polarization in these materials can be shaped by electronic structure, excited-state interactions, thin-film organization and device operation. This perspective opens new opportunities for circularly polarized OLEDs, chiral photodetectors and other optoelectronic devices where handedness can be generated, amplified and controlled in soft semiconductor materials.

Chirality is omnipresent in nature, bridging magnetic and molecular spin phenomena. At the core of this connection lies the chiral-induced spin selectivity (CISS) effect, describing the highly efficient generation of spin polarized currents in chiral
molecules. Despite extensive experimental evidence, the underlying mechanisms of CISS remain debated. Here, we show how chirality is directly linked to the intrinsic magnetic moments in molecules, introducting unidirectionality. Furthermore, we explore the impact of chirality on spin angular momentum in hybrid metal/ chiral molecule thin film heterostructures [1]. For this, we inject a pure spin current via spin pumping and investigate the spin-to-charge conversion at the hybrid chiral interface. Notably, we observe a chiral-induced unidirectionality in the conversion. Furthermore, angle-dependent measurements reveal that the spin selectivity is maximum when the spin angular momentum is aligned with the molecular chiral axis. Finally, we demonstrate how molecular design and organization can be harnessed to control spin phenomena at hybrid chiral molecule magnetic interfaces. Our findings pave a pathway towards functional ”chiralitronic” devices - turning a fundamental puzzle into a technological opportunity.

Abstract

Perovskite nanocrystals have emerged as one of the most promising semiconductor materials for next-generation optoelectronic applications due to their exceptional optical properties, including high photoluminescence quantum yield, narrow emission bandwidth, tunable bandgap, and solution-processability. These unique characteristics have enabled their widespread investigation for applications such as light-emitting diodes (LEDs), solar cells, lasers, and photodetectors. However, the conventional synthesis of perovskite nanocrystals relies on large volumes of organic solvents, generating significant chemical waste and increasing the environmental and economic costs of production.(1)

In this work, a sustainable strategy for perovskite nanocrystal synthesis is proposed through the recycling and reuse of the reaction solvent. Following each synthesis, the solvent is recovered, purified, and employed for the subsequent batch of nanocrystal synthesis to evaluate its influence on crystal growth, morphology, optical properties, and reproducibility. The resulting nanocrystals are then utilized as the emissive layer in LED device fabrication to investigate the effect of recycled solvents on device performance, including luminance, efficiency, and operational stability. (2)This approach aims to reduce solvent consumption and chemical waste while maintaining the high quality of perovskite nanocrystals, offering a practical pathway toward environmentally sustainable and cost-effective manufacturing of perovskite-based optoelectronic devices.