Organic light-emitting diodes based on new silole derivatives

Two light emissive organic light-emitting diodes (OLEDs) of high performance were prepared by vacuum thermal evaporation using two kinds of silole derivatives 1,2-bis(1-methyl-2,3,4,5-tetraphenyl-1H-silole-1-yl)ethane (BMPSiE) and 1,1'-dimethyl-3,3',4,4'-tetraphenyl-2,2',5,5'-tetra(thiophen-2-yl)-1,1'-bi(1H -silole) (BMPThSi) as emitting materials, N, N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine(NPB) and tris(8-hydroxyquinolinolato) aluminum (Alq(3)) ) as hole transporting layer (HTL) and electron transporting layer (ETL), respectively.The luminance-voltage and current density-voltage characteristics of devices were investigated, and the difference between their performances was discussed. The results demonstrate that at a bias voltage of 20 V, the device consisting of novel emissive material BMPSiE had a maximum luminance of 9991.9 cd.m(-2) and the device of BMPThSi had a maximum luminance of 15261.5 cd.m(-2). The peaks of electroluminescence (EL) spectra were located at 483 and 495 nm, respectively, which were in good accordance with the photoluminescent characteristics. The Commissions International d'Eclairage (CIE) coordinates were located at (0.202, 0.337) and (0.246, 0.419), which were independent on the variation of forward bias.