Energy level alignment at Alq3/La0.7Sr0.3MnO3 interface for organic spintronic devices

TL;DR

This study investigates the energy level alignment at the Alq3/LSMO interface, revealing a significant interface dipole that impacts hole injection barriers, crucial for understanding organic spintronic device performance.

Contribution

It provides detailed experimental insights into the energy level shifts and interface dipole at the Alq3/LSMO interface, advancing knowledge for organic spintronic device design.

Findings

Detected a 0.9 eV interface dipole shifting the energy diagram

Hole injection barrier increased to 1.7 eV, making hole injection more difficult

Observed weak interaction affecting N 1s core levels

Abstract

The electronic structure of the interface between Tris (8-hydroxyquinolino)-aluminum (Alq3) and La0.7Sr0.3MnO3 manganite (LSMO) was investigated by means of photoelectron spectroscopy. As demonstrated recently this interface is characterized by efficient spin injection in organic spintronic devices. We detected a strong interface dipole of about 0.9 eV that shifts down the whole energy diagram of the Alq3 with respect to the vacuum level. This modifies the height of the barriers for the holes injection to 1.7 eV, indicating that hole injection from LSMO into Alq3 is more difficult than it was expected as the energy level matched by vacuum levels. We believe the interface dipole is due to the intrinsic dipole moment characteristic for Alq3 layer. An additional weak interaction is observed between the two materials influencing the N 1s core levels of the organic semiconductor. The presented data are of greatest importance for both qualitative and quantitative description of the organic spin valves.