AVS 45th International Symposium
    Organic Electronic Materials Topical Conference Monday Sessions
       Session OE+EM-MoA

Paper OE+EM-MoA7
Charge Injection and Transport in Organic Films

Monday, November 2, 1998, 4:00 pm, Room 327

Session: Organic Thin Film Devices II: Transitors and Transport
Presenter: D.K. Murti, Xerox Research Centre of Canada
Correspondent: Click to Email
Charge injection and transport is important in many diverse organic electronic devices. For example, electroluminescent devices for display and organic photoreceptors for digital printers depend on injection and transport. In this presentation, the primary focus will be on the organic photoreceptor. Organic photoreceptors consist of a metal film with layers of organic photoconductor and molecularly doped polymers. Charge injection and transport at metal-phthalocyanine interfaces and phthalocyanine-molecularly doped polymer interfaces will be discussed in this presentation. In the photoinduced discharge technique, the surface is initially corona-charged and then followed by discharge of the surface potential with photogenerated carriers that are injected from phthalocyanine and transported in the tetraphenylbenzidine (TPD) doped polycarbonate film. Photoinduced discharge measurements indicate that photogenerated holes can be injected from phthalocyanine into TPD without charge trapping. Hole mobility and the electric field dependence were measured with the time-of-flight technique. In this technique, the drift of a sheet of holes injected from the phthalocyanine film is time-resolved; the transit time is determined in order to calculate the hole mobility at an applied electric field. Hole mobility showed dependence on the electric field with a mobility of about 1x10 @super -5@ cm@super 2@ / V.s at an electric field of 1x10 @super 4@ V/cm. Kelvin probe was used to determine the contact potential difference and changes in the work function of phthalocyanine and TPD. The relative work functions of phthalocyanine and TPD are 5.2 eV and 4.7 eV respectively based on Kelvin probe measurements. This indicates no barrier for hole injection as observed by photodischarge techniques.