Vapor Deposition Polymerization and Electrical Characterization of TPD Thin Films

Masakazu MUROYAMA  Ayako TAJIRI  Kyoko ICHIDA  Seiji YOKOKURA  Kuniaki TANAKA  Eiji OTSUKI  Hiroaki USUI  

IEICE TRANSACTIONS on Electronics   Vol.E94-C   No.2   pp.157-163
Publication Date: 2011/02/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E94.C.157
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Molecular and Organic Devices)
OLED,  DvTPD,  organic EL,  deposition polymerization,  

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Thin films of a divinyl derivative of tetraphenyldiaminobiphenyl DvTPD were prepared by vapor deposition followed by annealing. After annealing at 200°C for 1 h, the film became practically insoluble to organic solvents due to polymerization. Electrical characteristics of the films were measured by current-voltage measurement, time-of-flight measurement, and dielectric measurement. It was found that the hole mobility of DvTPD decreases when the film is polymerized. As a consequence of the decrease of hole mobility, carrier balance in the emissive layer of an organic light emitting diode (OLED) was improved, leading to a higher quantum efficiency and a pure emission spectrum. The dielectric measurement also confirmed the high thermal stability of the polymerized film.