Room temperature optoelectronic devices operating with spin crossover nanoparticles.
TL;DR: In this paper, the authors show how a graphene underlayer reveals the light-induced heating that triggers a spin transition, paving the way for using these molecules for room temperature optoelectronic applications.
Abstract: Molecular systems can exhibit multi-stimuli switching of their properties, with spin crossover materials having unique magnetic transition triggered by temperature and light, among others. Light-induced room temperature operation is however elusive, as optical changes between metastable spin states require cryogenic temperatures. Furthermore, electrical detection is hampered by the intrinsic low conductivity properties of these materials. We show here how a graphene underlayer reveals the light-induced heating that triggers a spin transition, paving the way for using these molecules for room temperature optoelectronic applications.
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TL;DR: In this paper, the authors introduce emerging 2DMs, various classes of macro-molecules, and molecular switches and discuss their relevant properties, and discuss the use of molecules and assemblies thereof to boost the performance of 2D transistors for CMOS applications and to impart diverse functionalities in beyond-CMOS devices.
Abstract: Two-dimensional materials (2DMs) have attracted tremendous research interest over the last two decades. Their unique optical, electronic, thermal, and mechanical properties make 2DMs key building blocks for the fabrication of novel complementary metal-oxide-semiconductor (CMOS) and beyond-CMOS devices. Major advances in device functionality and performance have been made by the covalent or noncovalent functionalization of 2DMs with molecules: while the molecular coating of metal electrodes and dielectrics allows for more efficient charge injection and transport through the 2DMs, the combination of dynamic molecular systems, capable to respond to external stimuli, with 2DMs makes it possible to generate hybrid systems possessing new properties by realizing stimuli-responsive functional devices and thereby enabling functional diversification in More-than-Moore technologies. In this review, we first introduce emerging 2DMs, various classes of (macro)molecules, and molecular switches and discuss their relevant properties. We then turn to 2DM/molecule hybrid systems and the various physical and chemical strategies used to synthesize them. Next, we discuss the use of molecules and assemblies thereof to boost the performance of 2D transistors for CMOS applications and to impart diverse functionalities in beyond-CMOS devices. Finally, we present the challenges, opportunities, and long-term perspectives in this technologically promising field.
25 citations
TL;DR: In this paper , a new discrete FeII neutral complex (FeIIL2]0 (1) based on a novel asymmetric tridentate ligand 2-(5-(3-methoxy-4H-1,2,4-triazol-3-yl)-6-(1H-pyrazol-1-yl))pyridine (L).
Abstract: Little is known about the mechanisms behind the bistability (memory) of molecular spin transition compounds over broad temperature ranges (>100 K). To address this point, we report on a new discrete FeII neutral complex [FeIIL2]0 (1) based on a novel asymmetric tridentate ligand 2-(5-(3-methoxy-4H-1,2,4-triazol-3-yl)-6-(1H-pyrazol-1-yl))pyridine (L). Due to the asymmetric cone-shaped form, in the lattice, the formed complex molecules stack into a one-dimensional (1D) supramolecular chain. In the case of the rectangular supramolecular arrangement of chains in methanolates 1-A and 1-B (both orthorhombic, Pbcn) differing, respectively, by bent and extended spatial conformations of the 3-methoxy groups (3MeO), a moderate cooperativity is observed. In contrast, the hexagonal-like arrangement of supramolecular chains in polymorph 1-C (monoclinic, P21/c) results in steric coupling of the transforming complex species with the peripheral flipping 3MeO group. The group acts as a supramolecular latch, locking the huge geometric distortion of complex 1 and in turn the trigonal distortion of the central FeII ion in the high-spin state, thereby keeping it from the transition to the low-spin state over a large thermal range. Analysis of the crystal packing of 1-C reveals significantly changing patterns of close intermolecular interactions on going between the phases substantiated by the energy framework analysis. The detected supramolecular mechanism leads to a record-setting robust 105 K wide hysteresis spanning the room temperature region and an atypically large TLIESST relaxation value of 104 K of the photoexcited high-spin state. This work highlights a viable pathway toward a new generation of cleverly designed molecular memory materials.
12 citations
TL;DR: In this paper, a strain-controlled spin transition in heterostructured metal-organic framework (MOF) thin films has been demonstrated, where the spin transition temperature of Ptpz can be controlled in the temperature range of 300-380 K by fabricating a nanometer-sized thin film with a Nipz buffer layer.
Abstract: Metal-organic framework (MOF) thin films have recently attracted much attention as a new platform for surface/interface research, where unconventional structural and physical properties emerge. Among the many MOFs as candidates for fabrication of thin films, Hofmann-type MOFs {Fe(pz)[M(CN)4]} [pz = pyrazine; M = Ni (Nipz), M = Pt (Ptpz)] are attractive, because they undergo spin transitions with concomitant structural changes. Here, we demonstrate the first example of a strain-controlled spin transition in heterostructured MOF thin films. The spin transition temperature of Ptpz can be controlled in the temperature range of 300-380 K by fabricating a nanometer-sized heterostructured thin film with a Nipz buffer layer, where the smaller lattice of Nipz causes epitaxial compressive strain to the Ptpz layer. The fabricated heterostructured thin film exhibited a remarkable increase in spin transition temperature with a dynamic structural transformation, confirmed by variable-temperature (VT) X-ray diffraction and VT Raman spectroscopy. By verifying interfacial strain in a heterostructured thin film, we can rationally control the characteristics of MOFs-not only spin transition but also various physical properties such as gas storage, catalysis, sensing, proton conductivity, and electrical properties, among others.
10 citations
TL;DR: In this paper, the length changes of individual switchable nanoparticles induced thermally by nanosecond laser pulses are compared with time-resolved optical measurements performed on an assembly of these particles.
Abstract: Spin Crossover (SCO) is a promising switching phenomenon when implemented in electronic devices as molecules, thin films or nanoparticles. Among the properties modulated along this phenomenon, optically induced mechanical changes are of tremendous importance as they can work as fast light-induced mechanical switches or allow to investigate and control microstructural strains and fatigability. The development of characterization techniques probing 2 nanoscopic behaviour with high spatio-temporal resolution allows to trigger and visualize such mechanical changes of individual nanoscopic objects. Here we use Ultrafast Transmission Electron Microscopy (UTEM) to precisely probe the length changes of individual switchable nanoparticles induced thermally by nanosecond laser pulses. This allows us to reveal the mechanisms of spin switching, leading to the macroscopic expansion of SCO materials. This study was conducted on individual pure SCO nanoparticles and SCO nanoparticles encapsulating gold nanorods that serve for plasmonic heating under laser pulses. Length changes are compared with time-resolved optical measurements performed on an assembly of these particles.
9 citations
TL;DR: In this article , the state of the art and configurations of Fe-based spin-crossover (SCO) functional devices on a range of scales are discussed. And a systematic overview in the characteristics of Fe based SCO functional devices and their corresponding performance is provided.
5 citations
References
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TL;DR: In this paper, a broad review of fundamental electronic properties of two-dimensional graphene with the emphasis on density and temperature dependent carrier transport in doped or gated graphene structures is provided.
Abstract: We provide a broad review of fundamental electronic properties of two-dimensional graphene with the emphasis on density and temperature dependent carrier transport in doped or gated graphene structures. A salient feature of our review is a critical comparison between carrier transport in graphene and in two-dimensional semiconductor systems (e.g. heterostructures, quantum wells, inversion layers) so that the unique features of graphene electronic properties arising from its gap- less, massless, chiral Dirac spectrum are highlighted. Experiment and theory as well as quantum and semi-classical transport are discussed in a synergistic manner in order to provide a unified and comprehensive perspective. Although the emphasis of the review is on those aspects of graphene transport where reasonable consensus exists in the literature, open questions are discussed as well. Various physical mechanisms controlling transport are described in depth including long- range charged impurity scattering, screening, short-range defect scattering, phonon scattering, many-body effects, Klein tunneling, minimum conductivity at the Dirac point, electron-hole puddle formation, p-n junctions, localization, percolation, quantum-classical crossover, midgap states, quantum Hall effects, and other phenomena.
2,930 citations
TL;DR: This critical review discusses recent work in the field of molecule-based spin crossover materials with a special focus on these emerging issues, including chemical synthesis, physical properties and theoretical aspects as well (223 references).
Abstract: Recently we assisted a strong renewed interest in the fascinating field of molecular spin crossover complexes by (1) the emergence of nanosized spin crossover materials through direct synthesis of coordination nanoparticles and nanopatterned thin films as well as by (2) the use of novel sophisticated high spatial and temporal resolution experimental techniques and theoretical approaches for the study of spatiotemporal phenomena in cooperative spin crossover systems. Besides generating new fundamental knowledge on size-reduction effects and the dynamics of the spin crossover phenomenon, this research aims also at the development of practical applications such as sensor, display, information storage and nanophotonic devices. In this critical review, we discuss recent work in the field of molecule-based spin crossover materials with a special focus on these emerging issues, including chemical synthesis, physical properties and theoretical aspects as well (223 references).
1,084 citations
631 citations
TL;DR: The spin crossover (SCO) complexes can be switched between low (LS) and high spin (HS) magnetic states with the help of an external perturbation and are promising candidates for the realization of molecule-based electronic and spintronic components, such as switching and memory elements as discussed by the authors.
496 citations
TL;DR: In this article, the authors discuss progress in the design, synthesis, and functioning of photochemical and electrochemical switches and chemical and light-driven molecular motors and discuss the anchoring of molecular motors on surfaces and molecular motors at work.
Abstract: Molecular switches and motors are essential components of artificial molecular machines. In this perspective, we discuss progress in our design, synthesis, and functioning of photochemical and electrochemical switches and chemical and light-driven molecular motors. Special emphasis is given to the control of a range of functions and properties, including luminescence, self-assembly, motion, color, conductance, transport, and chirality. We will also discuss our efforts to control mechanical movement at the molecular level, a feature that is at the heart of molecular motors and machines. The anchoring of molecular motors on surfaces and molecular motors at work are discussed.
438 citations