Cornerstone of molecular spintronics: Strategies for reliable organic spin valves

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.