Preparation and assessment of reliable organic spin valves

The long spin relaxation time of organic semiconductors up to millisecond level make organic spintronics an emerging and promising field, which has attracted wide range of interests since the birth of the first spin valve. Organic spin valve with sandwich structure is the typical device for spintronic study, and it is generally the vertical structure. During the device fabrication process, the organic semiconductor spacer is easily to be penetrated by top ferromagnetic metal atoms with high energy, and thus causes the formation of ill-defined layer at the interface between the top electrode and organic spacer. The ill-dedfined layer commonly includes filaments or pinholes, which will seriously affect the spin transport performance and spin-related multifunctional exploration. Therefore, reliable organic spin valve charactered by filament- and pinhole-free at the interface is strongly required. So far, a series of reliable spin valve preparation methods have been developed. In this review, following a simply introduction of spin valve, the advances of reliable spin valve preparation methods have been systematically discussed. Subsequently, the assessment approaches of reliable spin valve are presented. Finally, the challenges and perspectives towards the preparation and assessment of reliable spin valve are outlined to clarify the future efforts needed in this area.