Charge-up Durability and in-situ Tracking of a Photooxidation Process of Rubrene Studied by Photoelectron Yield Spectroscopy: Toward Photoelectronic Investigation on Organic Electronics Devices

Abstract

For the purpose of close understanding and further improvement of the organic electronics devices, elucidation of the electronic structures of organic-electrode interfaces as well as the organic materials themselves in the ambient pressure condition is highly anticipated. Ultraviolet Photoelectron spectroscopy (UPS) is not a satisfactory technique for this purpose, because UPS needs high vacuum condition in principle and the sample charging problem hinders characterization of the electronic structures of specimens of insufficient conductivity (e.g. organic thick-films and crystals). In the present study, the authors proved that one can observe the occupied electronic structures of insulating materials by photoelectron yield spectroscopy (PYS). A novel mechanism enabling photoelectron measurement on insulators is specified. By adopting this method, the electronic structures of rubrene thin films at a buried interface beneath the rubrene-peroxide layers were directly observed in the ambient air condition. These merits of PYS can be extended to investigate the electronic structure of organic devices.