title: Design and synthesis of novel anthracene derivatives as n-type emitters for electroluminescent devices: a combined experimental and DFT study.
abstract: Six novel anthracene-oxadiazole derivatives, 4a (2-(4-(anthracen-9-yl)phenyl)-5-p-tolyl-1,3,4-oxadiazole), 4b (2-(4-(anthracen-9-yl)phenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), 4c (2-(4-(anthracen-9-yl)phenyl)-5-(4-methoxyphenyl)-1,3,4-oxadiazole), 8a (2-(4-(anthracen-9-yl)phenyl)-5-m-tolyl-1,3,4-oxadiazole), 8b (2-(3-(anthracen-9-yl)phenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole) and 8c (2-(3-(anthracen-9-yl)phenyl)-5-(3,4,5-trimethoxyphenyl)-1,3,4-oxadiazole) have been synthesized and characterized for use as emitters in organic light emitting devices (OLEDs). They show good thermal stability (T(d), 297-364 °C) and glass transition temperatures (T(g)) in the range of 82-98 °C, as seen from the thermo gravimetric analysis and differential scanning calorimetric studies. The solvatochromism phenomenon and electrochemical properties have been studied in detail using UV-Vis absorption, fluorescence spectroscopy and cyclic voltammetry. TD-DFT calculations have been carried out to understand the electrochemical and photophysical properties. The spatial structures of 4b and 8c are further confirmed by X-ray diffraction analysis. Un-optimized non-doped electroluminescent devices were fabricated using these anthracene derivatives as emitters with the following device configuration: ITO (120 nm)/α-NPD (30 nm)/4a-4c or 8a-8c(35 nm)/BCP (6 nm)/Alq3 (28 nm)/LiF (1 nm)/Al (150 nm). Among all the six compounds, 8a displays the maximum brightness of 1728 cd m(-2) and current efficiency 0.89 cd A(-1). Furthermore, as an electron transporter, 8a exhibited superior performance (current efficiency is 11.7 cd A(-1)) than the device using standard Alq3 (current efficiency is 8.69 cd A(-1)), demonstrating its high potential for employment in OLEDs. These results indicate that the new anthracene-oxadiazole derivatives could play an important role in the development of OLEDs.
authors.affiliation: Crop Protection Chemicals Division, Indian Institute of Chemical Technology, Hyderabad 500007, India.
authors.forename: G
authors.initials: G
authors.lastname: Mallesham
authors.forename: S
authors.initials: S
authors.lastname: Balaiah
authors.forename: M
authors.initials: M
authors.lastname: Ananth Reddy
authors.forename: B
authors.initials: B
authors.lastname: Sridhar
authors.forename: Punita
authors.initials: P
authors.lastname: Singh
authors.forename: Ritu
authors.initials: R
authors.lastname: Srivastava
authors.forename: K
authors.initials: K
authors.lastname: Bhanuprakash
authors.forename: V
authors.initials: V
authors.lastname: Jayathirtha Rao