Study on blue organic light-emitting diodes doped with 4,4 '-bis(9-ethyl-3carbazovinylene)-1,1 '-biphenyl in various host materials

摘要

We have fabricated efficient blue organic light-emitting devices (OLEDs) with 4,4'-bis (9-ethyl-3carbazovinylene)-1,1'-biphenyl(BCzVBi) as the fluorescent emitter doped into 4,4'-bis(carbazol-9-yl)biphenyl (CBP) and 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), respectively, and the results show that luminance and luminous efficiency are greatly enhanced in the doped devices. Particularly, the optimized blue CBP-host device with a well-designed structure has a significantly higher luminous efficiency of 4.45 cd/A. The energy level structure of the BCzVBi molecules is obtained, which yields useful information on the light emission processes. We carry out a spectroscopic analysis based on Gaussian multi-peak fit for the electroluminescence (EL) emission spectra and present a theoretical explanation of the energy transfer mechanism in the host-guest system. These are expected to provide an effective strategy in enhancing high-efficiency blue OLEDs. (C) 2016 Elsevier B.V. All rights reserved.