Bimolecular Excited States Based on 3DTAPBP: Electromer and Exciplex
ZHU Wei-yi1, JIN Min-feng1, TU Xie-hao1, ZHANG Ye-feng1, YIN Yue-hong2, Lü Zhao-yue1*
1. Department of Physics, East China University of Science and Technology, Shanghai 200237, China
2. Department of Applied Physics, Institute of Physical Chemistry, Henan Polytechnic University, Jiaozuo 454000, China
Abstract：The emission of bimolecular excited states was investigated in 3DTAPBP (2,2’-bis(3-(N,N-di-p-tolylamino) phenyl) biphenyl), which is one of aniline compounds. The emission of both monomer excitons (blue light centered at 420 nm) and electromer (yellow light peaked at 578 nm) was observed in the organic light emitting diode (OLED) fabricated with 3DTAPBP monolayer (ITO/MoO3/3DTAPBP/LiF/Al). A white OLED can be fulfilled by using the monomer exciton emission and the electromer emission, which is a very simple approach for achieving white OLED. For instance, a white light can be attained at 7.0 V in the device of ITO/MoO3/3DTAPBP/LiF/Al, with a Commission Internationale de l’clairage (CIE) color coordinates of (0.36, 0.31). However, the brightness and efficiency were extremely poor because of the serious imbalance of carrier injection and transport in the single layer device. In addition, a bilayer device (ITO/MoO3/3DTAPBP/TPBi/LiF/Al) were fabricated with 3DTAPBP and the electron transport material TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl) benzene). The emission peaked at around 490 nm, originating from exciplex formed at 3DTAPBP/TPBi interface, which was observed due to the accumulation of carriers at the interface. The energy of the photons is generally in agreement with the energy difference between HOMO (the highest occupied molecular orbital) of 3DTAPBP and LUMO (the lowest unoccupied molecular orbital) of TPBi. The decomposition of electroluminescent spectra with Lorentzian fitting exhibited found that the intensity of exciplex emission decreased with the increase of voltage. The reason is that more carriers tunnel cross the interface barrier of 3DTAPBP/TPBi, resulting in the increase of monomer emission of 3DTAPBP. Under the application of voltages at 4, 6, and 8 V, the color coordinates were respectively (0.28, 0.35), (0.24, 0.29), and (0.27, 0.28). And the luminous color was within the range of white at a voltage of 8 V. The highest brightness and maximum current efficiency of bilayer devices were 1 349.2 cd·m-2 and 1.22 cd·A-1, respectively.
Key words：3DTAPBP; Electromer; Commission Internationale de L’Eclairage; Exciplex; White light
朱唯一，金敏峰，屠燮豪，张叶峰，殷月红，吕昭月. 3DTAPBP的双分子激发态——电致激基缔合物和激基复合物[J]. 光谱学与光谱分析, 2018, 38(08): 2344-2349.
ZHU Wei-yi, JIN Min-feng, TU Xie-hao, ZHANG Ye-feng, YIN Yue-hong, Lü Zhao-yue. Bimolecular Excited States Based on 3DTAPBP: Electromer and Exciplex. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2018, 38(08): 2344-2349.
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