Benzobisoxazole cruciforms: a tunable, cross-conjugated platform for the generation of deep blue OLED materials

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2016-01, Vol.4 (17), p.3765-3773
• Main Authors: Chavez III, Ramiro, Cai, Min, Tlach, Brian, Wheeler, David L, Kaudal, Rajiv, Tsyrenova, Ayuna, Tomlinson, Aimée L, Shinar, Ruth, Shinar, Joseph, Jeffries-EL, Malika
• Format: Article
• Language: English
• Subjects: Electronic devices; Emission; Emitters; Luminance; MATERIALS SCIENCE; Molecular orbitals; Platforms; Thermal stability; Weight loss
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c5tc03622d

Four new cross-conjugated small molecules based on a central benzo[1,2- d :4,5- d ′]bisoxazole moiety possessing semi-independently tunable HOMO and LUMO levels were synthesized and the properties of these materials were evaluated experimentally and theoretically. The molecules were thermally stable with 5% weight loss occurring well above 350 °C. The cruciforms all exhibited blue emission in solution ranging from 433-450 nm. Host-guest OLEDs fabricated from various concentrations of these materials using the small molecule host 4,4′-bis(9-carbazolyl)-biphenyl (CBP) exhibited deep blue-emission with Commission Internationale de L'Eclairage (CIE) coordinates of (0.15 ≤ x ≤ 0.17, 0.05 ≤ y ≤ 0.11), and maximum luminance efficiencies as high as ∼2 cd A −1 . These results demonstrate the potential of benzobisoxazole cruciforms as emitters for developing high-performance deep blue OLEDs. A structure-property investigation of a series of cross-conjugated molecules shows that their performance is dependent on both the nature of the substituents and their conjugation axis.