Photoemission Spectroscopy Characterization of Attempts to Deposit MoO2Thin Film

Irfan Irfan,Yongli Gao,Franky So

doi:10.1155/2011/314702

Abstract

Attempts to deposit molybdenum dioxide (MoO2) thin films have been described. Electronic structure of films, deposited by thermal evaporation of MoO2powder, had been investigated with ultraviolet photoemission and X-ray photoemission spectroscopy (UPS and XPS). The thermally evaporated films were found to be similar to the thermally evaporated MoO3films at the early deposition stage. XPS analysis of MoO2powder reveals presence of +5 and +6 oxidation states in Mo 3d core level along with +4 state. The residue of MoO2powder indicates substantial reduction in higher oxidation states while keeping +4 oxidation state almost intact. Interface formation between chloroaluminum phthalocyanine (AlPc-Cl) and the thermally evaporated film was also investigated.

Highlights

Applications of organic semiconductors (OSCs) are increasingly attracting interest of both scientific and industrial communities because of its low synthesis cost and tunable material properties
Introduction of a high work function (WF) transition metal oxide insertion layer between conducting indium tin oxide (ITO) and organic semiconductors was an attempt first made by Tokito et al [9]
The thermal evaporation of MoO2 powder was performed in the evaporation chamber of the VG ESCA system, as described in the experimental details

Summary

Introduction

Applications of organic semiconductors (OSCs) are increasingly attracting interest of both scientific and industrial communities because of its low synthesis cost and tunable material properties. In our reports [13,14,15,16], we have established the efficiency enhancement by a reduced hole injection barrier and a drift field from hole accumulation in the organic material at the ITO/hole injection layer interface. Greiner et al [21] and Vasilopoulou et al [22] have recently reported that the reduced molybdenum trioxide film (MoOx and x ∼ 2.7) outperforms the stoichiometric trioxide film, due to the presence of defect states in the former. These reports invoke interest in the investigation of MoO2 film as an interlayer. Work we discuss our investigation of MoO2 deposition attempts and the interface formation with

A MoOx

Experimental Details

Results and Discussion

Conclusion