Modification of the organic/La0.7Sr0.3MnO3 interface by in situ gas treatment

Abstract La 0.7 Sr 0.3 MnO 3 (LSMO) can act as a spin injection electrode in organic spin-valves and organic light-emitting devices. For the latter application, good control of the electronic structure of the organic/LSMO interface is a key issue to ensure sufficient current injection in the device. By exposing cleaned LSMO surfaces to activated oxygen and hydrogen, the work function of the samples can reach 5.15 and 4.3 eV, respectively, as shown by in situ photoemission measurements. The initial stage of formation of the organic/LSMO interface upon deposition of N , N ′-bis-(1-naphyl)- N , N ′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) onto the oxygen-treated LSMO surface is examined. We find that the NPB molecules evenly cover the LSMO surface and that the interface barrier height is 0.8 eV, which is comparable to that at the NPB/indium tin oxide (ITO) interface with the ITO surface pretreated in situ by oxygen plasma.