Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (08): 2000-2007.doi: 10.3866/PKU.WHXB201206071

• PHOTOCHEMISTRY AND RADIATION CHEMISTRY • Previous Articles     Next Articles

Synthesis and Optoelectronic Properties of Blue-Emitting Star-Burst Oligomers Based on Triphenylamine and Spiro(fluorene-9,9'-xanthene)

CHU Zeng-Ze, WANG Dan, ZHANG Chao, ZOU De-Chun   

  1. Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2012-05-07 Revised:2012-06-07 Published:2012-07-10
  • Contact: ZOU De-Chun E-mail:dczou@pku.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50833001) and National Key Basic Research Program of China (973) (2011CB933300).

Abstract:

Three star-burst conjugated oligomers based on triphenylamine (TPA), fluorene and spiro (fluorene-9,9'-xanthene) (SFX) have been synthesized via the Sonogashira cross-coupling reaction. These well-defined oligomers possess high decomposition temperatures (Td) at 417, 439, and 425 °C, respectively. Differential scanning calorimetry (DSC) demonstrates two oligomers which incorporate the SFX unit, TPA-SFX and TPA-SFXCz, possess higher glass transition temperatures (Tg) at 141 and 127 ° C, respectively, compared with 101 °C for TPA-F. The investigation of their optical properties shows TPA-SFX and TPA-SFXCz exhibit a single blue emission in film with emission peaks at 434 and 442 nm, respectively, whereas TPA-F shows a broad double-peak emission located at 424 and 455 nm, which implies the nonplanar TPA and spiro SFX moieties can effectively restrict the formation of aggregates or excimers. Electrochemical investigations show that these oligomers have relatively high HOMO levels at around -5.4 eV due to incorporation of the electron-rich TPA core. Electroluminescence (EL) devices with a configuration of ITO (indium tin oxide)/PEDOT:PSS (poly(3,4-ethylenedioxythiophene): poly (styrenesulfonate))/ oligomer/TPBI (1,3,5-tris(1-phenyl-1H -benzimidazol-2-yl)benzene)/LiF/Al were constructed using these oligomers as the emitter by spin-coating, with TPBI as the electron-transporting and hole-blocking layer. The device using TPA-SFX as the emitting layer exhibits bright blue emission with the maximum brightness and maximum current efficiency of 2680 cd·A-2 and 0.35 cd·A-1, and CIE color coordination of (0.17, 0.13).

Key words: Organic light-emitting diodes, Triphenylamine, Spiro(fluorene-9,9'-xanthene), Star-burst, Blue-emitting materials

MSC2000: 

  • O644