Organic Spin‐Valves and Beyond: Spin Injection and Transport in Organic Semiconductors and the Effect of Interfacial Engineering

• Published in: Advanced materials (Weinheim) Vol. 29; no. 2; pp. np - n/a
• Main Authors: Jang, Hyuk‐Jae, Richter, Curt A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-01-2017
• Subjects: Carrier injection; Crystal structure; Efficiency; Ferromagnetism; interface engineering; Interlayers; Magnetic moments; Materials science; Organic semiconductors; Scattering; Semiconductor research; Single crystals; spin injection and transport; Spin valves; Spintronics; spin‐valve effects; Surface mount technology; Thin films; Transport; Valves; organic semiconductors; spin injection and transport; spin-valve effects; interface engineering
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201602739

Since the first observation of the spin‐valve effect through organic semiconductors, efforts to realize novel spintronic technologies based on organic semiconductors have been rapidly growing. However, a complete understanding of spin‐polarized carrier injection and transport in organic semiconductors is still lacking and under debate. For example, there is still no clear understanding of major spin‐flip mechanisms in organic semiconductors and the role of hybrid metal–organic interfaces in spin injection. Recent findings suggest that organic single crystals can provide spin‐transport media with much less structural disorder relative to organic thin films, thus reducing momentum scattering. Additionally, modification of the band energetics, morphology, and even spin magnetic moment at the metal–organic interface by interface engineering can greatly impact the efficiency of spin‐polarized carrier injection. Here, progress on efficient spin‐polarized carrier injection into organic semiconductors from ferromagnetic metals by using various interface engineering techniques is presented, such as inserting a metallic interlayer, a molecular self‐assembled monolayer (SAM), and a ballistic carrier emitter. In addition, efforts to realize long spin transport in single‐crystalline organic semiconductors are discussed. The focus here is on understanding and maximizing spin‐polarized carrier injection and transport in organic semiconductors and insight is provided for the realization of emerging organic spintronics technologies.
The progress on efficient spin‐polarized carrier injection into organic semiconductors from ferromagnetic metals by using various interface engineering techniques, since the first observation of the spin‐valve effect through organic semiconductors, is presented. In addition, efforts to realize long spin transport in single‐crystalline organic semiconductors compared to organic thin films are discussed.