Electroluminescent Properties of a Novel σ*–π* Conjugated Polymer, Poly[1,1-(2,3,4,5-tetraphenylsilole)]

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Abstract
The optical and electronic properties of a σ*–π* conjugated polymer, poly[1,1-(2,3,4,5-tetraphenylsilole)] (PTPS), have been studied. PTPS shows emissions of σ*–π and π*–π transitions at 356 and 520 nm, respectively. PTPS light-emitting diodes (LEDs) with a single layer structure emit green-yellow light, corresponding to the π*–π transition, with an external quantum efficiency of 3×10-2%. The effect of the doping of poly(methylphenylsilane) (PMPS), a good hole transport material, into PTPS has also been studied. The shapes of the photoluminescence spectra of PMPS:PTPS films are the same as those of a PTPS film, indicating efficient energy transfer from PMPS to PTPS. PTPS:PMPS LEDs emit essentially the same green-yellow light as PTPS LEDs and exhibit better device characteristics than those without PMPS, that is, smaller turn-on voltages, larger current densities, and larger external quantum efficiencies. The PMPS:PTPS (PMPS: 30 wt%) LEDs show a luminance of 27 cd/m2 at a driving current density of 13 mA/cm2.