"Research on organic spintronics, which is especially promising due to the prospects of exceptionally long spin lifetimes in organic semiconductors, is currently in a critical phase. After a very successful starting period, progress is now being hampered, largely due to a limited understanding of the critical interfacial properties involved. The mechanisms behind the observed spin valve effects remain poorly understood, and unambiguous evidence of spin polarized transport (other than tunnelling) in organic semiconductors is still lacking. The properties of the hybrid inorganic/organic interfaces are of paramount importance for the device behaviour, and are key to solving the puzzle associated with the physics behind the observed magnetoresistance effects. So far a direct link between device characteristics and interfacial properties remains elusive. In this proposal, we pursue a reliable way to address these crucial issues and to guarantee the progress needed to take the field to the next level.As a first main objective, we will combine interface preparation and characterization with in-situ device fabrication and testing, using a single dedicated UHV setup equipped with all necessary tools, i.e. spin (and angle) resolved photoelectron spectroscopy, LEED and STM, and magnetotransport, to establish a direct link between interfacial properties and device characteristics. The second main objective is to develop new device architectures, optimized for electrical probing of spin polarization in organic semiconductors. These joined efforts form a highly challenging task, since they require a strongly interdisciplinary approach, combining different complementary expertises. The PI is in a truly unique position to carry out this timely project successfully, having a strong and well documented background in 1) electron spectroscopic characterization techniques of electronic and magnetic properties of hybrid interfaces and 2) spintronic devices and spin polarized transport."