Spin Transport in Organic Molecules.
TL;DR: In this review, the recent advances of spin transport in π-conjugated molecular materials, considered as promising for spintronics development, have been highlighted, including molecular single crystal, cocrystal, solid solution as well as other highly ordered supramolecular structures.
Abstract: Because of the considerable advantages of functional molecules as well as supramolecules, such as the low cost, light weight, flexibility, and large area preparation via the solution method, molecular electronics has grown into an active and rapidly developing research field over the past few decades. Beyond those well-known advantages, a very long spin relaxation time of π-conjugated molecules, due to the weak spin-orbit coupling, facilitates a pioneering but fast-growing research field, known as molecular spintronics. Recently, a series of sustained progresses have been achieved with various π-conjugated molecular matrixes where spin transport is undoubtedly an important point for the spin physical process and multifunctional applications. Currently, most studies on spin transport are carried out with a molecule-based spin valve, which shows a typical geometry with a thin-film molecular layer sandwiched between two ferromagnetic electrodes. In such a device, the spin transport process has been demonstrated to have a close correlation with spin relaxation time and charge carrier mobility of π-conjugated molecules. In this review, the recent advances of spin transport in these two aspects have been systematically summarized. Particularly, spin transport in π-conjugated molecular materials, considered as promising for spintronics development, have also been highlighted, including molecular single crystal, cocrystal, solid solution as well as other highly ordered supramolecular structures.
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TL;DR: The introduction of pure-spin-current-type molecular spintronic devices that have already demonstrated great potential for multifunction exploration are introduced, and the challenges and outlook that make this field young and energetic are outlined.
Abstract: The field of spintronics has triggered an enormous revolution in information storage since the first observation of giant magnetoresistance (GMR). Molecular semiconductors are characterized by having very long spin relaxation times up to milliseconds, and are thus widely considered to hold immense potential for spintronic applications. Along with the development of molecular spintronics, it is clear that the study of multipurpose spintronic devices has gradually grown into a new research and development direction. The abundant photoelectric properties of molecular semiconductors and the intriguing functionality of the spinterface, together with novel designs of device structures, have promoted the integration of multiple functions and different mechanisms into discrete spintronic devices. Here, according to the different relationships between the integrated mechanisms, multifunctional molecular spintronic devices containing parallel and interactive types are highlighted. This is followed by the introduction of pure-spin-current-type molecular spintronic devices that have already demonstrated great potential for multifunction exploration. Finally, the challenges and outlook that make this field young and energetic are outlined.
89 citations
44 citations
TL;DR: In this paper, the first progress in organic and perovskite-based spintronics is reviewed, which will enable the manipulation of spin, charges, and photons in spin/optoelectronic devices.
Abstract: Spin‐related phenomena in optoelectronic materials can revolutionize several technological applications in the areas of data processing and storage, quantum computing, lighting, energy harvesting, sensing, and healthcare. A fundamental boost to this promising field can be envisaged thanks to the use of two emerging materials, which have recently been receiving increasing scientific attention: organic semiconductors (OSCs) and halide perovskites (HPs). Here, the first progress in the resulting fields, organic‐ and perovskite‐based spintronics, is reviewed, which will enable the manipulation of spin, charges, and photons in spin/optoelectronic devices. A link between these two classes of materials is created by highlighting the pros and cons of each technology, and their potential applications in new multifunctional spintronic devices are discussed. Current challenges in the field are also outlined, and convenient approaches to overcome them are proposed.
37 citations
TL;DR: In this review, the application of OSCs in spintronic study will be succinctly discussed, the most important and extensive application, the long-distance spin transport property of O SCs will be discussed first, and several multifunctional spintronics devices based on OSCS will be summarized.
Abstract: π-Conjugated semiconductors, primarily composed of elements with low atomic number, are regarded as promising spin-transport materials due to the weak spin-orbit coupling interaction and hence long spin relaxation time. Moreover, a large number of additional functions of organic semiconductors (OSCs), such as the abundant photo-electric properties, flexibility, and tailorability, endow the organic spintronic devices more unique properties and functionalities. Particularly, the integration of the photo-electric functionality and excellent spin transport property of OSCs in a single spintronic device has even shown great potential for the realization of spin manipulation in OSCs. In this review, the application of OSCs in spintronic study will be succinctly discussed. As the most important and extensive application, the long-distance spin transport property of OSCs will be discussed first. Subsequently, several multifunctional spintronic devices based on OSCs will be summarized. After that, the organic-based magnets used for the electrodes of spintronic devices will be introduced. Finally, according to the latest progress, spin manipulation in OSCs via novel spintronic devices together with other prospects and challenges will be outlined.
19 citations
TL;DR: In this article, the authors focus on the recent progress in strategies for reliable fabrication and evaluation of typical organic spin valve (OSV) in vertical configuration and highlight three points for attention including selection of bottom electrodes, optimization of organic spacer, and prevention of metal penetration.
Abstract: Organic spin valve (OSV), one of the most promising and representative devices involving spin injection, transport and detection, has drawn tremendous attention owing to their ultra-long spin relaxation time in the field of molecular spintronics. Since the first demonstration of truly worked vertical OSV device in 2004, efforts in enhancement of high performance and pursuit of spin-related nature have been devoted in related field. It offers a new opportunity to develop the integrated flexible multi-functional arrays based on spintronics in the future. However, the unreliable working state in OSVs due to the lack of exploration on interface control will cause severe impact on the performance evaluation and further restrict their practical application. Herein, we focus on the recent progress in strategies for reliable fabrication and evaluation of typical OSVs in vertical configuration. Firstly, the challenges in protection of two spin interface properties and identification of spin-valve-like signals were proposed. Then, three points for attention including selection of bottom electrodes, optimization of organic spacer, and prevention of metal penetration to improve the device performance and reliability were mentioned. Particularly, various modified strategies to solve the “dead layer” issue were highlighted. Furthermore, we discussed the general protocols in the reliable evaluation of OSVs’ performance and transport mechanism identification. Notably, several key fundamentals resulting in spurious magnetoresistance (MR) response were illustrated. Finally, we also highlighted the future perspectives on spintronic devices of organic materials.
16 citations
References
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TL;DR: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron, which has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices.
Abstract: This review describes a new paradigm of electronics based on the spin degree of freedom of the electron. Either adding the spin degree of freedom to conventional charge-based electronic devices or using the spin alone has the potential advantages of nonvolatility, increased data processing speed, decreased electric power consumption, and increased integration densities compared with conventional semiconductor devices. To successfully incorporate spins into existing semiconductor technology, one has to resolve technical issues such as efficient injection, transport, control and manipulation, and detection of spin polarization as well as spin-polarized currents. Recent advances in new materials engineering hold the promise of realizing spintronic devices in the near future. We review the current state of the spin-based devices, efforts in new materials fabrication, issues in spin transport, and optical spin manipulation.
9,917 citations
"Spin Transport in Organic Molecules..." refers background in this paper
...The spin degree of freedom of electrons exhibits particular potential on information nonvolatile memory, transport, and processing (Wolf et al., 2001)....
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TL;DR: A highly soluble and printable n-channel polymer exhibiting unprecedented OTFT characteristics under ambient conditions in combination with Au contacts and various polymeric dielectrics is reported and all-printed polymeric complementary inverters have been demonstrated.
Abstract: Printed electronics is a revolutionary technology aimed at unconventional electronic device manufacture on plastic foils, and will probably rely on polymeric semiconductors for organic thin-film transistor (OTFT) fabrication. In addition to having excellent charge-transport characteristics in ambient conditions, such materials must meet other key requirements, such as chemical stability, large solubility in common solvents, and inexpensive solution and/or low-temperature processing. Furthermore, compatibility of both p-channel (hole-transporting) and n-channel (electron-transporting) semiconductors with a single combination of gate dielectric and contact materials is highly desirable to enable powerful complementary circuit technologies, where p- and n-channel OTFTs operate in concert. Polymeric complementary circuits operating in ambient conditions are currently difficult to realize: although excellent p-channel polymers are widely available, the achievement of high-performance n-channel polymers is more challenging. Here we report a highly soluble ( approximately 60 g l(-1)) and printable n-channel polymer exhibiting unprecedented OTFT characteristics (electron mobilities up to approximately 0.45-0.85 cm(2) V(-1) s(-1)) under ambient conditions in combination with Au contacts and various polymeric dielectrics. Several top-gate OTFTs on plastic substrates were fabricated with the semiconductor-dielectric layers deposited by spin-coating as well as by gravure, flexographic and inkjet printing, demonstrating great processing versatility. Finally, all-printed polymeric complementary inverters (with gain 25-65) have been demonstrated.
2,769 citations
Additional excerpts
...85 (Yan et al., 2009) LSMO/P(NDI2OD-T2)/AlOx/Co 42 nm @ 300K (Li et al....
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TL;DR: The injection, transport and detection of spin-polarized carriers using an organic semiconductor as the spacer layer in a spin-valve structure is reported, yielding low-temperature giant magnetoresistance effects as large as 40 per cent.
Abstract: A spin valve is a layered structure of magnetic and non-magnetic (spacer) materials whose electrical resistance depends on the spin state of electrons passing through the device and so can be controlled by an external magnetic field. The discoveries of giant magnetoresistance and tunnelling magnetoresistance in metallic spin valves have revolutionized applications such as magnetic recording and memory, and launched the new field of spin electronics--'spintronics'. Intense research efforts are now devoted to extending these spin-dependent effects to semiconductor materials. But while there have been noteworthy advances in spin injection and detection using inorganic semiconductors, spin-valve devices with semiconducting spacers have not yet been demonstrated. pi-conjugated organic semiconductors may offer a promising alternative approach to semiconductor spintronics, by virtue of their relatively strong electron-phonon coupling and large spin coherence. Here we report the injection, transport and detection of spin-polarized carriers using an organic semiconductor as the spacer layer in a spin-valve structure, yielding low-temperature giant magnetoresistance effects as large as 40 per cent.
1,298 citations
"Spin Transport in Organic Molecules..." refers background in this paper
...At the initial research stage, thin-film semiconductors with low mobility are usually used as the spin transport layer, which is normally prepared via thermal evaporation (Xiong et al., 2004; Nguyen et al., 2012)....
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...OSC Thin Films Since the first observation of giant magnetoresistance (GMR) in 8-hydroxy-quinoline aluminum (Alq3) (Xiong et al., 2004), a variety of OSC thin films have been applied as the spacer in spin valves....
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TL;DR: The results suggest that the fabrication approach constitutes a promising step that might ultimately allow to utilize high-performance organic single-crystal field-effect transistors for large-area electronics applications.
Abstract: Organic flexible electronics are being developed for computer displays, radio frequency identification tags, sensors and devices that have not been dreamt of yet. Practical applications so far are few, as their electrical performance is poor compared with conventional electronics. In terms of charge carrier mobility, however, field-effect transistors made of organic single crystals have a very high performance. The obstacle to the use of single-crystal devices is that they have to be individually hand-made. The report of a method of fabricating large arrays of high performance transistor devices by direct patterning of single crystals onto clean silicon surfaces or flexible plastics may help to change that. The new method retains the high performance of field-effect transistors even after significant bending. Field-effect transistors made of organic single crystals are ideal for studying the charge transport characteristics of organic semiconductor materials1. Their outstanding device performance2,3,4,5,6,7,8, relative to that of transistors made of organic thin films, makes them also attractive candidates for electronic applications such as active matrix displays and sensor arrays. These applications require minimal cross-talk between neighbouring devices. In the case of thin film systems, simple patterning of the active semiconductor layer9,10 minimizes cross-talk. But when using organic single crystals, the only approach currently available for creating arrays of separate devices is manual selection and placing of individual crystals—a process prohibitive for producing devices at high density and with reasonable throughput. In contrast, inorganic crystals have been grown in extended arrays11,12,13, and efficient and large-area fabrication of silicon crystalline islands with high mobilities for electronic applications has been reported14,15. Here we describe a method for effectively fabricating large arrays of single crystals of a wide range of organic semiconductor materials directly onto transistor source–drain electrodes. We find that film domains of octadecyltriethoxysilane microcontact-printed onto either clean Si/SiO2 surfaces or flexible plastic provide control over the nucleation of vapour-grown organic single crystals. This allows us to fabricate large arrays of high-performance organic single-crystal field-effect transistors with mobilities as high as 2.4 cm2 V-1 s-1 and on/off ratios greater than 107, and devices on flexible substrates that retain their performance after significant bending. These results suggest that our fabrication approach constitutes a promising step that might ultimately allow us to utilize high-performance organic single-crystal field-effect transistors for large-area electronics applications.
968 citations
"Spin Transport in Organic Molecules..." refers background in this paper
...Single Crystals Organic semiconductor single crystals, with a perfect crystal texture, minimal density of defects, and an absence of grain boundaries have exhibited very high mobility (>5 cm2/Vs) and unique physicochemical properties, which have developed rapidly in recent years (Briseno et al., 2006; Fan et al., 2013; Wang et al., 2018; Zhang et al., 2018)....
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...…perfect crystal texture, minimal density of defects, and an absence of grain boundaries have exhibited very high mobility (>5 cm2/Vs) and unique physicochemical properties, which have developed rapidly in recent years (Briseno et al., 2006; Fan et al., 2013; Wang et al., 2018; Zhang et al., 2018)....
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TL;DR: The main experimental results and their connections with devices such as light-emitting diodes and electronic memory devices are summarized, and the scientific and technological issues that make organic spintronics a young but exciting field are outlined.
Abstract: Organic semiconductors are characterized by a very low spin–orbit interaction, which, together with their chemical flexibility and relatively low production costs, makes them an ideal materials system for spintronics applications. The first experiments on spin injection and transport occurred only a few years ago, and since then considerable progress has been made in improving performance as well as in understanding the mechanisms affecting spin-related phenomena. Nevertheless, several challenges remain in both device performance and fundamental understanding before organic semiconductors can compete with inorganic semiconductors or metals in the development of realistic spintronics applications. In this article we summarize the main experimental results and their connections with devices such as light-emitting diodes and electronic memory devices, and we outline the scientific and technological issues that make organic spintronics a young but exciting field.
717 citations
"Spin Transport in Organic Molecules..." refers background in this paper
...Although the experimentally measured spin transport distance is comprehensively affected by magnetic electrodes, spin injection efficiency, device fabrication, etc (Dediu et al., 2009), a clear relationship that can be found is that the spin transport distance has obviously been enhanced in OSCs with higher mobility....
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...Organic spintronics has thus attracted extensive attention in the past decade (Dediu et al., 2009; Sanvito, 2011) after the successful spin injection in molecular materials was first reported (Dediu et al....
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