Raman Spectra and Current-Voltage Characteristics of 4,4′,4″-Tris(2-naphthylphenylamino)triphenylamine Thin Films

• Published in: Molecular crystals and liquid crystals (Philadelphia, Pa. : 2003) Vol. 498; no. 1; pp. 183 - 192
• Main Authors: Park, Kyeong Nam, Cho, Young-Rae, Kim, Wonho, Park, Dae-Won, Choe, Youngson
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 25.02.2009
• Subjects: 2-TNATA; electromagnetic field; molecular ordering; OLED; Raman spectra
• ISSN: 1542-1406; 1563-5287; 1543-5318
• DOI: 10.1080/15421400802616038

A thin film of vacuum-deposited 2-TNATA (4,4′,4″-Tris(2-naphthylphenylamino) triphenylamine), usually used as a hole injection layer (HIL) in OLEDs, was annealed after deposition and treated with electromagnetic field in order to get the film molecularly-ordered and analyzed by AFM, SEM and Raman spectroscopy. The treated film was placed between indium tin oxide (ITO) electrode and hole injection layer to investigate the current density-Voltage (J-V) and luminance-voltage (L-V) characteristics of the organic light-emitting diodes. According to the Raman spectra results, as-deposited 2-TNATA thin film was not molecularly ordered, and the films treated by the thermal annealing at near the glass transition temperature of 2-TNATA and electromagnetic field, were molecularly ordered and showed the significant increases of current density and luminance efficiency for devices at a given voltage compared to an as-deposited 2-TNATA film.