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.
Bibliographical noteFunding Information:
This work is supported by the National Natural Science Foundation of China. The ICTP-Elettra Users Programme provides partial support for the work done at Elettra. The authors thank Dr. S. Lizzit for technical assistance at the SuperESCA beamline. XZW thanks Student Innovation Foundation of NSRL for supporting his travels to NSRL.
- Organic/magnetic interface
- Spin injection
- Surface treatment
- Synchrotron radiation